probably not the last word on cooling....

[brent]

When my a/c is on, this beast still gets way too hot. I never want to go through another summer like this.
In theory, I shouldn't have a problem. Of all the posts in all the months, I'm on top of 95% of the important things. I've been working off your posts and suggestions like crazy. I even went down to a 13lb cap and 180 thermo and new rad hoses this weekend. DIDN'T COOL THE SNARLING BEAST ONE DEGREE!!
Things that are suspect:
1) I have no fan clutch (yet)
2) Water pump is stock
3) I think I'm gonna buy an oil cooler this weekend
Other than that, you can't nail me on anything cooling-related (shroud and fan distance/coolant mix/hoses/sending unit/radiator itself/etc etc etc).
Still-----I have no faith that addressing any of the remaing three issues will keep my truck cool.
Disgusted, Brent

[Tad]

If you have no fan clutch what are you running?
I was assured by my hot rod neighbor that a 6 blade flex fan would pull... SO MUCH MORE AIR...

Well, been fooled before but it ani't true this time, at 32% less blade area it don't add up.

7 blade fan, HD clutch (had/owned all this to start) is way better air flow.

[Michael]

If no fan clutch then.....no cool

[Joe Guilbeau]

What theory brought you to the conclusion that a 13 lb Radiator Cap was the was to go?

[brent]

13lb cap--read here that lowering the lbs would help a degree or two, that's all.
No fan clutch--overall consensus from reading is that it might be worth a couple of degrees but couldn't possibly be the ROOT OF ALL EVIL, could it?
And I have a 6-blade, metal, fairly new fan, with the PO's shim still in place keeping it half-in/half-out the shroud.
Fan clutch the key to 10-15 degree drop?

[BIGYELLOW78J10]

The area of the blade is not everything, the angle matters too. But I am not about to replace my stock fan, thouhg my clutch has seen better days.

Is there anyway to test a cool fan on a non running engine?

What are you running for coolant? When was the last time you flushed your cooling system?

And define too hot? In the red, or cooking you slowly, overcoming the A/C and making your fingers plump like hot dogs?

Even with a new radiator, there is always a chance something random got in tand blocks a passage or 10.

good luck,

Daniel

[brent]

Runnin normal Prestone, 50/50. Flushed block and rad three months ago.
"Too hot" is coming around the bend to the red, close enough to make me nervous, and over halfway past the green. Add another length when idling at a Sonic waiting for a malt.
If we can say the red zone="4'oclock" and startup temp is at the 8oclock then when it's hot its averaging 6:30 to 7 oclock if this makes any sense at all.
That little exhausted shimmy it does when idling worries the bejeezus out of me.

[River Beast]

guess this aint the las post on cooling now is it? ;)

Trust me..... these cooling posts will be archived....

[Joe Guilbeau]

FSJ Radiators and Cooling

Cooling seems to get a lot of attention, so here is the deal.

First an experiment…

Take a pot and put some tap water in it and bring up the heat until steam bubbles begin to form on the bottom of the pot. This will approximate the exhaust water-cooling passages on the AMC motors. Take a big spoon and stir the water so that it flows in CW or CCW rotation, and get it flowing very slowly at first. Note the results. Now stir faster, note the results as the water continues to rotate in the pot. Now take the spoon and swirl in the opposite direction of the water flow just enough to prevent the water from rotating in the pot. Note the reaction. Do this over and over and note the results. Some conclusions should be forming, namely that the flow of water over the surface of the pot, inhibits steam bubbles from forming. This is important for quite a few reasons, namely that once steam bubbles begin to form, they isolate the metal surface which in turn gets hotter, and water as strange as it may seem, is a better heat transfer medium than steam.

When the pot was stirred faster, it took longer for the steam bubbles to form, right?

Faster water flows will inhibit steam bubbles from forming, all other things being equal. The flow of water rushing over the surface area of the pot or the interior of the engine, wipes away the hot spots, if you will.

Adding to that mix, if you pressurize the water, it raises the boiling temperature of the water there by reducing steam bubble generation.

Another observation that I have been prone to notice is that the larger the surface area of a particular radiator the more BTU’s of heat it will be able to transfer from coolant as it passes through, all other things being equal.

The system is designed to operate in a closed loop fashion, with the water pump being fed by the outlet of the radiator. The water pump sends the water flowing through the block, past the head gaskets through the cylinder heads, cooling off the exhaust ports and combustion chambers, while the heads are routing the coolant past the intake manifolds to the thermostat.

The upper radiator hose sends whatever coolant the thermostat and water pump can manage to deliver to the inlet of the radiator, which acts as a heat exchanger to transfer excessive heat to the atmosphere, through the airflow of ambient air flowing through the radiator cooling fins.

You need at least 1 square inch of radiator surface area per cubic inch of motor, I have an AMC-360 probably bored at .030 over, and my radiator is 425 square inches.

I also have about 16 louvered fins per linear inch on that radiator, which allows enough airflow to cross ventilate the 4 staggered rows of vertical oblong tubes that dissipate the heat that the coolant is carrying. There is a point where the density of fins per linear inch of radiator will begin to restrict air flow through the radiator, especially at highway speeds as the air dam builds up in front of the vehicle. I have observed that my radiator can cool as much as 40 degrees from the intake to the outlet.

For the increasing coolant flow, I have a FlowKooler mechanical water pump mated to an Evans modified Robert Shaw thermostat, rated at 180 degrees. Opening the radiator cap, and starting the engine and running her until the thermostat opens up reveals that there is quite a lot of water being moved by the impeller blades of the pump.

It flies past the radiator cap orifice. There is a plate that is attached to the back of the impeller blades, which improves low speed water flow, and at high speeds, reduces impeller blade cavitations. Keep in mind that even the highest flowing water pump and associated high flow thermostat can only move as much coolant thru the closed loop systems as the closed loop systems restrictions allow.

I use a 20-23 lb rated radiator cap to further pressurize the coolant to raise the boiling temperature. The reason that a thermostat is important is that it keeps the vehicle within the design parameters, as internal combustion engines all have a preferred operating zone in terms of engine temperatures. It also helps provide backpressure on the impeller blades, thus helping to prevent cavitations, a very nasty occurrence.

Now this may not work for you, as the cooling system is a closed loop system, the rated pressure of your radiator (or water pump seepage qoutient, or radiator hose, etc...) may not be able to withstand the added working pressure that the 20-23 lb. Radiator cap may impose. Let the buyer beware.

Finally, since pure water is superior to any antifreeze on the market, I use it to more efficiently transfer the heat from the engine to the radiator.

Since pure distilled water will soon rust in the system, anti-corrosion additives are needed, and since the water pump likes some lubrication, I use Water Wetter and Preston Anti-Corrosion and Lubricant for pure water systems.

Other things to consider are the tendencies of antifreeze additives to de-compose thus adding solvent solids to the coolant mix, dissolved calcium in tap waters are a bother, as are the mineral contents of tap water in some locations.

Not changing and flushing out all of these solids on a regular basis, creates problems. The disolved solids seek the lowest portion of the system that they can locate and reside at, in many cases this leads to build ups being massed just inside the lowest portion of the radiator and available to be sucked in after being jogged loose by traversing rough terrain, therby being fed directly to the impeller blades of the water pump.

Just go out and look at the water jacket of that ole block lying around to see the effects of crud and scale build up.

So keep in mind that in most cases we are attacking the weakest link in the cooling system, and whatever improvements made, may very well reveal the next weakest link in that chain.

So some of us end up chasing one thing after another and get frustrated in the process. So, if you read through this and decide to fix her up, and go out and buy that 23 lb Radiator cap that I am so fond of touting, you may just find out how good that ole water pump really is, it may start leaking, creating steam pockets, harming your engine, and reducing coolant levels in the system, not to mention what might happen to the head gaskets.

Speaking of gaskets, be careful of silicon, any excess gasket material that finds its way into the coolant, will not help the situation at all.

To properly troubleshoot overheating and cooling issues, we must not rely on urban legends; facts work nicely here as in any troubleshooting endeavors.

In order to troubleshoot, we need data that is confirmable, and repeatable.

So, measuring the temperature of the incoming coolant to the radiator, and measuring the out flowing temperature from the radiator is required, in order to collect data and determine what is really happening in the system. The temperature gauge in the vehicle is simply not good enough.

Thermocouples are an idea choice as most multimeters allow thermocouple inputs.

Most of us have access to thermocouples, and the small interfaces that allow two thermocouples to be placed in the radiator inlet and outlet tubes can be had for a very reasonable price.

Now, getting back to the radiator and the design parameters of operation…

On my FSJ, this equates to a 180 degree Evans modified Robert Shaw thermostat, with a set point of 180 degrees. My inlet water temperature to the radiator when at 100 degrees ambient temperature is normally about 195 degrees, and at the outlet of the radiator it is about 155-165 degrees, during normal engine operations.

A 20 inch 7-blade, 2 ¾ inch pitch fan from a Dodge 400/440 with a Heavy Duty Fan Clutch is indeed helpful, but we need a fan shroud in order to insure that all of the air being drawn by the fan is pulled through the radiator and not from underneath the vehicle.

A custom fan shroud may just be the ticket here, with a felt gasket to seal that shroud to the back of the radiator surface. Any self respecting sheet metal shop can fabricate a fan shroud out of stainless steel. Have them bend a rectangle to fit up against the radiator core, insuring that it can be sealed up against the radiator with a felt gasket and it engages the fan by at least ½ of the blade depth.

Now a circle cut out to enclose 1/2 of the fan blade thickness can be brazed on the rectangle to finish the shroud, making sure that the edges are sanded to remove burrs and sharp edges.

Fabricate tabs to mount to the radiator mounting points. Just insure that there is enough space between the blade tips and the shroud so that flexing of the engine on the motor mounts and flex of the chassis over terrain will not cause a problem with mechanical interference between the blades and the shroud. Give it at least a 1/2 inch berth.

The radiator should drop the temperature of the coolant by about 20-30 degrees when the coolant flows through the radiator, at a minimum. This is the difference between the inlet temperature and the outlet temperature of the radiator.

A radiator that does not cool by 20-30 degrees either is not getting enough airflow, or the coolant is not efficient enough to keep up with the heat load.

Several issues to address here. A lot of folks run 50/50 mixtures of coolant to water. Not the best idea in the Summer, as the stronger the solution of antifreeze to water mixture ratio becomes, the less efficient the coolant becomes as a heat transfer medium.

As mentioned earlier, we should be striving to optimize the efficiency of the system, and another tool we have at our disposal is the physical properties of water, it is simply a better medium for heat transfer that antifreeze.

Any addition of antifreeze begins to degrade the heat transfer qualities of water. So, if you are positive that during the summer months, that the vehicle will not be subjected to sub freezing temperatures, then why not optimize the efficiency of the system by substituting distilled water.

Why distilled water? Well, tap water will contain minerals, and dissolved solids, and chemicals and lime and all sorts of bad things for the engine. So just use distilled water.

But using distilled water only as your coolant will soon result in rust and provides no lubrication to the water pump, which desperately needs lubrication. So use Preston’s Anti-Corrosion and Lubricant or even perhaps some Water Wetter.

You may hear that by doing this we have lowered the boiling point of the coolant enough that disaster will now strike. This is another reason for the suggested 20-23 lb. Radiator cap, to increase the pressure in the system to raise the boiling point of the coolant to an acceptable level.

An additional benefit is that this further pressurizes the system so that impeller blade cavitations are not an issue. Replace the stock water cooler with a Miloden or Flowkooler to take that out of the equation, the higher flow through the closed loop system is worth the expenditure.

So, a 4-row staggered core, 16-louvered fins per inch of linear radiator with a surface area of 1 square inch per cubic inch of motor with an additional 20% engineering overhead for those tough heating days.

An Evans modified Robert Shaw 180-degree thermostat, Flowkooler or Miloden Water Pump, and a 20-23 lb pressure rated radiator cap get us the hardware to get us started.

With a flush out of the water jackets inside the engine to remove all that scale and gunk… lots of gunk there guaranteed..., and using distilled water with Preston Anti-Corrosion/Lubricant and/or Water Wetter, to prevent the distilled water from forming rust and corrosion, we have our heat transfer medium all in order.

The coolant flows through the radiator faster so it has less time to shed it's heat, BUT it also flows through the block at the same rate, and therefore does not absorb AS MUCH heat...bottom line is that the engine runs cooler.

Added turbulence from the high flow water pump and high flow thermostat scrubs off vaporization areas around exhaust ports and prevents steam bubbles from forming. Thus adding to the efficiency of the system.

The radiator also has more cores and more rows thus removing additional restrictiion to the coolant flow rates.

Now we can move on to the subject of diagnosing cooling issues.

Again, we need to get those thermocouples mounted on the radiators. Infrared hand held temperature meters are also available.

When the inlet temperature is generally around 190 degrees and the return outlet temperature is 165-175 degrees or lower depending upon ambient air temperatures, then we can pretty much agree that the rig is operating per the design parameters that were set by the good folks at AMC at the beginning of the odyssey.

When the inlet temperature is about 220-plus degrees, and the outlet temperature is pretty close to air temperature, we can theorize that very little water is flowing through the radiator, but what is flowing through is being stripped of its heat per design parameters, otherwise the outlet temperature of the radiator would be raised substantially, right?

So, some possibilities are the thermostat is not opening fully, to allow the heated block water to transition to the radiator or the water pump is no longer operational and there is not enough coolant flowing through the system. This is bad, and fairly easy to troubleshoot. The hoses on the vehicle will give some indication, the top hose is extremely hot, and the lower hose is not near as hot, but does not seem to be full of coolant and it is feeling rather feeling. This indicates that not enough water is being returned to the block, causing the lower radiator hose to collapse in some cases

Now, if the inlet temperature or the temperature gauge is spiking and cools down when the engine rpm’s pick up (as a recent post suggests), then we have a condition that leads me to believe that excessive heat is being generated, when the engine rpm’s pick up, the problem is reduced.

This would seem to indicate that revving the engine has some beneficial effects. If the temperature change were immediate, then we would suspect that low coolant levels or low pressure in the system is allowing heated steam to form and influence the temperature sender or thermocouples.

There is a possible leak in the system, so when the vehicle is stopped and the hood is opened while the engine is still running, one may carefully release the pressure on the radiator cap, no sudden pressure release and you have found your problem, most likely a worn out radiator cap.

Since the coolant level is not at the desired level or pressure, steam my form and be trapped at the top portion of the closed loop system, generally in the thermostat housing and hose area along with the top portion of the radiator, all of these areas will be super hot. This will degrade the seal on the radiator cap and test the integrity of the radiator.

OK, another situation might be that the inlet temperature is high again, 220 degrees or so, and the outlet temperature is also very high. So we might suspect that the heat transfer of the coolant is not keeping up with the demands of the system. What might cause this to happen can be one of several distasteful options.

One is that the radiator must be capable of handling the heat load, again we go back to the basic design theory that 1 square inch of radiator surface area is needed for every cubic inch of engine, with at least a 20% overhead, this translates to at least a 25-inch wide radiator with 17 inches height minimum, with the right design parameters of 3 to 4 cores with the right amount of fins per linear inch. The ideal behind a 4-staggered core is that the cores are not subjected to the heating that is stripped off by the 1st or 2nd row. Also, the extra rows increase the volumn of coolant available, thus aiding in cooling. Another benefit of adding rows, is that increased fin area is provided further assisting the heat transfer process. Finally, the added tubes provide for additional flow, thus increasing the flow rate of the coolant thru the closed loop system.

Two, there must be enough coolant flow to circulate through the system in order to transfer enough heat to keep up with the heat load. As long as we have the high output water pumps and the high flow thermostats, this probably can be ignored.

Three might be that we have enough radiator and enough coolant and that the coolant is flowing efficiently enough to keep up with the heat loads, but there is not enough air flow across the radiator to scrub sufficient heat to keep up with the heat load.

Speaking of radiators, most of ours are older than 20 years; the tubes are made of stuff about 0.010 of an inch thick. The **** thing is held together by acid core solder, just how tuff do you think this stuff is? And lets face it; most of the engine heat is dissipated in exhaust anyway.

How about when the engine overheats and we turn on the Heater to assist in cooling. If this works you have increased the cooling fin surface area of the radiator and you have increased the airflow across those fins in the heater core, while simultaneously increasing the total amount of coolant available to shed BTU's.

Now, here is where some folks join in the fray with Heavy Duty Fan Clutches and Flex Fans and such.

Kind of makes you wonder if enough consideration was given to the other areas of the closed loop system.

That this solution has worked for so many is a testimony to the fact that the closed loop system probably worked when the vehicle was new, but being twenty to thirty years old. Bored over as most of our rigs are, and given the fact that the radiators most of us are using are probably not nearly new with some blocked passages, and the ole water pumps have impeller blades eaten by cavitations, and the thermostat we just put in last year was a bargain for $3.87 at the local auto parts store, and the coolant is probably more like 80% antifreeze to 20% tap water, which has resulted in coolant dissolved solids and minerals and calcium deposits throughout the system, it is no wonder that we spout off so about any kind of improvement at all.

So, adding that heavy-duty fan clutch gets just enough oomph to get us over the hump and is universally agreed upon as the Holy Grail of Cooling.

Well, it is not a bad idea, my ONLY problem with this solution is that if we address the engineering behind the Heavy Duty Fan Clutch we find that it is designed to prevent the fan from turning at the same rate of the water pump shaft.

This gives quieter operation (no howling) and perhaps better gas mileage. Also at higher speeds, the fan is slowed so as not to intefere with the air dam that has built up in front of the vehicle.

Which brings up another issue, air dams can build up so as to prevent some air entering the engine compartment, due to the height and flow rate of air underneath our rigs.

Once we put that into perspective, we realize that the fan clutch is in reality a boon, to those systems that have been designed and are in the middle of their operational parameters, so that the clutch can slip when additional airflow may not be needed, or additional air flow may be available when required, by having the clutch engage the fan and not allow it to slip as much.

Of note on fan clutches is that as the engine rpm rises, the bi-metallic spring on some models cools off and allows the clutch engage the fan more, resulting in a area of rpm range where it actually allows the system to heat further. Reducing the speed sometimes improves this situation.

I just wanted to throw some things out there to consider, before everyone just starts to tear into their rigs and throw parts at potential problems, plus share some of the things that I have observed along the way.

[Wesdog]

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/anbet2.gif

[AJ Johnson]

lmao........

[River Beast]

Originally posted by Wesdog:
http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/anbet2.gifOH YES!!!!! I FULL-HEARTEDLY AGREE!!!

GREAT!!!

[Wesdog]

I can't add much to what Joe posted above. I gotta say Joe that you really laid it all out in a nicely organized and understandable post. Thanks for pointing out the interaction between the T-stat and providing a restriction/backpressure to the impeller to help prevent cavitation. I knew there was an interaction between the pump and t-stat but I have been having problems getting a clear picture in my mind about how a closed system fuctions with regard to pressure, flow and restrictions, I keep thinking in terms of the operation other types of systems such as the AC or Oiling systems and it is confusing. I also read somewhere about how the radiators tubes in the core are designed to create turbulence to help stir the cooling fluid as it passes through the core.

Here's a photo of the modified Robertshaw t-stat from the Stewert website. It shows one of the extra 3/8" holes you mentioned. Evans offers the same thing as you pointed out:

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/thermostat.gif

I like photos as they help people like me get a clear picture of what is being described.

Thanks for taking the time to put together that great post. Even after spending the last few years working on my cooling system I still have many things to learn and re-learn.

Have you used a sacrificial anode in your system to help cut down on the effects of electrolysis? When using water as the cooling fluid this becomes a consideration I believe.

Wesdog

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/wesdog_avitar1.jpg

[ July 15, 2003, 07:40 AM: Message edited by: Wesdog ]

[brent]

Add my unworthiness as well, and thanks. Something completely different to think about. That's one for the record books.
Gonna be an interesting weekend at least....THANKS

[reddog]

Your Jeep runs hot because you live in Tempe in the SUMMER!! It is very HOT there I hear... :D

Thats all I can add after Joe's post.

Kerry

[ July 15, 2003, 08:10 AM: Message edited by: reddog ]

[jeepjake]

Any self respecting sheet metal shop can fabricate a fan shroud out of stainless steel. Have them bend a rectangle to fit up against the radiator core, insuring that it can be sealed up against the radiator with a felt gasket and it engages the fan by at least ½ of the blade depth.

So..., why doesn't some enterprising person find a shop that needs some business right now, design a shroud and market one to the FSJ (and CJ) crowd for less than what's available?

Someone HAS to be out of work right now and have time to pursue this, someone else HAS to have a few $'s to help put into this enterprise? Anyone?...., anyone?..., Bueler????

[Green Giant]

New $4 thermostat, coolant drain & refill(~50/50), and a $24 fan clutch fixed my cooling problem. Guess I didn't know any better. :rolleyes:

[letank]

very impressive Joe.

I believe, that you can even get a 21" 7 blades fan for the 440.....

I have been running distilled water / prestone 50/50 for more than 10 years.... so no one should worry about the slightly more acidic distilled water.... it does not dissolve the copper solder....

Michel

[JAllenWAG]

I started running hot after my rebuild and upgrades so I put in a cheap 180 t-stat and it didn't do anything. I put a mr. gasket performance 180 in and it runs about 15-20 degrees cooler now. The mr. gasket t-stat was only a few dollars more at advance auto.

[Wage]

Joe,

You da man! I have my rig at the radiaotor shop today. Having HD rad built, 180 High flow t-stat installed, and HD fan clutch. I will tackle larger fan blade and shroud after I fid\gure out how to pay for this!

Joe,

Thank you man!

[mandoneer]

The only thing I have to say on this is that I run a very modified 327 (yes AMC, not chebby!!!) and a 2 core (yes 2core)V6 Rad. & a 1700 cfm elet. fan & no probs. !!!(even towing a 66 T-Bird convt. (4900 lbs appx.) on a trailer that weighs 3000 pounds= 7900 towing RIGHT?)BTW it's got a th400 for all you that think that "oh he can't have an auto 'cause it adds more heat"(no mech. fan at all)
These motors cooled fine from the factory (ALL AMC'S)---If you are having probs. your prob is NOT! likley in the cooling system , its in the motor--- IF YOUR RAD. IS CLEAN , YOUR CLUTCH IS WORKING AND YOUR THERMO IS OPENINING you should have no probs. PERIOD - I have been reading almost all the posts about cooling from even befor I was a member and they don't make any logic to me . If I am wrong PLEASE LET ME KNOW !! Like I said about my set-up ,it works great !and I have nothing but a hodge'podge of parts .. I may have gotten luckey BUT if it flows good it cools good ---(my experience) you all do have some points but, If and I mean "IF" it wont cool you have bigger issues --like head gaskets or a leaky freeze plug or intake or even timing - JUST MY 2 PENNYS , Also never , and I mean never run it with-out a thermo - YES your gauge will read lower but this is only because you are only in effect cooling 6 cyls the last two are dependent on the pressure to make the coolent circulate I.E. not enough pressure = path of least reastance and the path of least restance will by-pass the jacket on the last 2 cyl. on both sides(last cyl on each side) (and maybe the last 2 on driverside and the last 1 on the pass. side)It depends what block you have and what year it is because they DID MAKE CHANGES TO THE COOLING JACKET)The bottom line is that if your parts are functioning you should have no prob. with stock parts .(some heavy,heavy mods are exempt from this) ( I have obvously DOWN-GRADED my parts -- (to make them fit) ) People will tell you the easiest thing to MASK the prob.But it dos'nt fix the prob.--FIX THE PROBLEM AND YOU ARE GOOD TO GO !! otherwise you will have bigger issues to deal with down the road witch will cost you more --DONT GET ME WRONG I ALSO RELY ON THE INFANATE WISDOM OF THE BOARD ALL THE TIME . But find the problem , dont just through parts at it !!!once again ,,,IF I AM WRONG ,SOMEONE, ANYONE PLEASE LET ME KNOW -----------------ANGER IS A GIFT
Best regaurds to all who read this (DONT WANT TO STEP ON ANY TOES)
just my thoughts!

[eugene75]

Originally posted by mandoneer:
The only thing I have to say on this is that I run a very modified 327 (yes AMC, not chebby!!!) and a 2 core (yes 2core)V6 Rad. & a 1700 cfm elet. fan & no probs. !!!(even towing a 66 T-Bird convt. (4900 lbs appx.) on a trailer that weighs 3000 pounds= 7900 towing RIGHT?)BTW it's got a th400 for all you that think that "oh he can't have an auto 'cause it adds more heat"(no mech. fan at all)
These motors cooled fine from the factory (ALL AMC'S)---If you are having probs. your prob is NOT! likley in the cooling system , its in the motor--- IF YOUR RAD. IS CLEAN , YOUR CLUTCH IS WORKING AND YOUR THERMO IS OPENINING you should have no probs. PERIOD - I have been reading almost all the posts about cooling from even befor I was a member and they don't make any logic to me . If I am wrong PLEASE LET ME KNOW !! Like I said about my set-up ,it works great !and I have nothing but a hodge'podge of parts .. I may have gotten luckey BUT if it flows good it cools good ---(my experience) you all do have some points but, If and I mean "IF" it wont cool you have bigger issues --like head gaskets or a leaky freeze plug or intake or even timing - JUST MY 2 PENNYS , Also never , and I mean never run it with-out a thermo - YES your gauge will read lower but this is only because you are only in effect cooling 6 cyls the last two are dependent on the pressure to make the coolent circulate I.E. not enough pressure = path of least reastance and the path of least restance will by-pass the jacket on the last 2 cyl. on both sides(last cyl on each side) (and maybe the last 2 on driverside and the last 1 on the pass. side)It depends what block you have and what year it is because they DID MAKE CHANGES TO THE COOLING JACKET)The bottom line is that if your parts are functioning you should have no prob. with stock parts .(some heavy,heavy mods are exempt from this) ( I have obvously DOWN-GRADED my parts -- (to make them fit) ) People will tell you the easiest thing to MASK the prob.But it dos'nt fix the prob.--FIX THE PROBLEM AND YOU ARE GOOD TO GO !! otherwise you will have bigger issues to deal with down the road witch will cost you more --DONT GET ME WRONG I ALSO RELY ON THE INFANATE WISDOM OF THE BOARD ALL THE TIME . But find the problem , dont just through parts at it !!!once again ,,,IF I AM WRONG ,SOMEONE, ANYONE PLEASE LET ME KNOW -----------------ANGER IS A GIFT
Best regaurds to all who read this (DONT WANT TO STEP ON ANY TOES)
just my thoughts!I guess I'll put my thermostat back in now!!

[Joe Guilbeau]

Originally posted by mandoneer:
[QB]
I have been reading almost all the posts about cooling from even befor I was a member and they don't make any logic to me . If I am wrong PLEASE LET ME KNOW !! ,,,IF I AM WRONG ,SOMEONE, ANYONE PLEASE LET ME KNOW -----------------ANGER IS A GIFT
QB]If a logical progression towards anger management via interaction within the settings of a themed message board…along with it’s associated intermingled social commentaries with you is wrong…then; I don't want to be right.

[Wesdog]

Matt,
If you have read some of the other posts about cooling issues you will have seen that the tune state of the engine is always mentioned as a possible cause for cooling related problems. Every individual situation is unique and is usually a combination of many factors including both the state of engine tuning and the cooling system components as well as the environment contributing to an overheating condition. We are all just trying to help each other here. There is no one right answer that fits every situation in this area and Joe's post listing out how to investigate and correct the COOLING SYSTEM side of the problems was very helpful to anyone with enough awareness to recognize what it was intended to convey. I think you had many very valid points is your post also but you lost me in the tone of it and in that area I have to say you were wrong. I am incorrect in some of the info I share with board from time to time also and we are all here to learn. Saying a 13 to 40 year old vehicle was fine from the factory and so should cool fine now works in perfect world, maybe, but engine and cooling systems age and corrode and we are dealing with the current condition not the past. I think your statemant "IF YOUR RAD. IS CLEAN , YOUR CLUTCH IS WORKING AND YOUR THERMO IS OPENINING you should have no probs. PERIOD" is way overly simplifying the situation and topic under discussion. So a block with clogged cooling system passages or bad radiator cap or defective waterpump or ..... I hope you see my point. YES, absolutely the state of the tune of the engine must be checked. But so must the overall condition of the cooling system and how it is functioning NOW not when it came from the factory. I do agree with most of what you had to contribute but it could have been worded differently to get the message across. I agree that it is very important to check the tune of the engine because if something is seriously wrong that can be overloading the cooling system capacity and only addressing the cooling system could be masking an engine problem that needs to be corrected. I hope you take this message in the spirit it was meant and not as a flame or slap at you.

Regards, Wes

[ July 17, 2003, 08:04 AM: Message edited by: Wesdog ]

[Joe Guilbeau]

Matt was just having a little bit of fun as was I.

His gathering of parts together to adequately cool his vehicle indicates a more thorough undertanding of cooling issues than his post suggests.

So Matt, if you could...how about giving us the receipe that has worked for you on your vehicle.

The surface area in square inches of the radiator
how many fins per inch.

The fan blade (no of blades, flex or fixed, shroud or no shroud, etc...)

Another interesting observations might be that the engine bay in your vehicle perhaps has more fee air surrounding it than an AMC 360, so perhaps heat build up in the engine bay is not as much an issue for you.

For a rather severe test of your cooling system, try pulling that trailer up the 6-7% grade on State Route 188 along side Roosevelt Lake in Arizone for the 8-12 miles or so of the incline, at ambient temperatures of 115 degrees or so in the summer.

This is kind of the acid test in my opinion, as I have not seen too many other combination of heat and loads that are put on engines that will test the vehicle like this road will.

A major problem is that this road is saturated with rigs pulling travel trailers, and the 30 mph to 45 mph speeds that you are limited to, really test the air flow and cooling capabilites of a rig.

You can find lots of vehicles pulled over to the side with hoods raised and spewing radiators...

Those of you in Arizona who are familiar with this road can give us your own observations, this is the road where I found out how effective the addition of electric cooling fans were for my FSJ.

[fsj1978]

The trial-by-fire piece of road we use is the section of I40 coming west from Laughlin, it's long, and very steep. We've only made it all the way over once or twice w/o pulling over due to (of all things) vapor lock. No spewing radiator here. I'm still working bugs out of our poor, ol' FSJ that's use for towing. This is with about a 3,500lb trailer and we're hoping to eventually pull 8-9,000 over this same piece of road. I've looked HARD to trying to put in a physically larger radiator but it doesn't look like it'd do-able without spending MASSIVE amounts of time altering the front sheetmetal. We've done away with the A/C system and have moved the trans coolers(2) outboard so they're not in front of the radiator. We do have a winch (BAD!!!) and have an engine oil cooler mounted down as low as possable, in front of the radiator. Unfortunately at speeds over 60 or so, the airflow over the winch sends the air right over the top of the oil cooler and our engine oil typically runs 220 solo and about 230-240 towing (slower speed).
Sorry guys, just realized I'm RAMBLING terrably here, and not contributing a dang thing!

Chris

[Wesdog]

Originally posted by Joe Guilbeau:
Matt was just having a little bit of fun as was I.

His gathering of parts together to adequately cool his vehicle indicates a more thorough undertanding of cooling issues than his post suggests.
Must be a Texas thing! :rolleyes: Ok, I'll just STFU.

BTW, I am a poster child for how a engine tuning problem can overload the cooling system. I had a failing electric fuel pump that caused my engine to run real lean under heavy load. Of course I didn't know this was happening cause I didn't have a fuel pressure guage to tell me there was a fuel supply problem. It's just got REAL hot real fast pulling a steep grade in the desert. Ended up deforming some pistons and that sucks!

Wes

[Joe Guilbeau]

Originally posted by fsj1978:
We've only made it all the way over once or twice w/o pulling over due to (of all things) vapor lock.I will keep it short here...an electric fuel pump mounted at the cross member at the gas tank that pressurizes the fuel will cure your vapor lock.

Use a fuel pressure regulator right at the carb/fuel injectors to regulate the pressure for your paticular application.

No more vapor lock.

I could really go on and on the vapor lock thang, but will instead pour a full cup of STFU for the time being.

[Jeepadilly]

[ July 17, 2003, 08:32 PM: Message edited by: Jeepadilly ]

[Jeepadilly]

Originally posted by Joe Guilbeau:


For a rather severe test of your cooling system, try pulling that trailer up the 6-7% grade on State Route 188 along side Roosevelt Lake in Arizone for the 8-12 miles or so of the incline, at ambient temperatures of 115 degrees or so in the summer.

This is kind of the acid test in my opinion, as I have not seen too many other combination of heat and loads that are put on engines that will test the vehicle like this road will.

A major problem is that this road is saturated with rigs pulling travel trailers, and the 30 mph to 45 mph speeds that you are limited to, really test the air flow and cooling capabilites of a rig.

Thank you Joe for your scientific yet easy to understand approach to this important subject. Bear has always been the subject of admiring conversation when it came to cooling issues. A/C on...up hills...desert running...etc. After a trip leg from Bishop CA to Lake Sabrina (Bishop @ 5000 ft/109 deg to Sabrina 8000 ft/101 deg in a total of 18 miles or so up a 7% grade) towing a 3000 lb tent trailer, she over heated and I was sincerely humbled. Your information here has helped me perhaps the most of any other post on this board thus far...cooling issues involve so many variables and if one simply follows the advice of others without being able to apply the ideas you set for for himself...one might spent much time and money and still not really solve the problem...My Thanks!!! :D

[ July 17, 2003, 08:30 PM: Message edited by: Jeepadilly ]

[fsj1978]

We're running 15psi of fuel pressure on a Holley FI system. That was with TWO fuel pumps mounted just ahead of the X-member, and both of them running. We had super major vapor lock problems going and coming from Ouray last year. I'm hoping I got them fixed by doing an in-tank fuel pump. This however has lead to it's own problem since the pickup is in the far back end of the tank... I put a baffle in to create a pocket of fuel for downhills but guess what happens if you park nose-down with 1/2 tank of fuel??? <sigh> More mods !!!

Chris

[Marvin Gates]

I'm not sure if anyone has mentioned it or not (I didn't read every post) but the first thing you need to do is take the stock temperature gauge and throw it as far as you can, and get a real gauge to find out for sure what is going on.
Stock gauges are absolute junk! smile.gif smile.gif :D

[Joe Guilbeau]

Originally posted by fsj1978:
We're running 15psi of fuel pressure on a Holley FI system. That was with TWO fuel pumps mounted just ahead of the X-member, and both of them running. We had super major vapor lock problems going and coming from Ouray last year. I'm hoping I got them fixed by doing an in-tank fuel pump. This however has lead to it's own problem since the pickup is in the far back end of the tank... I put a baffle in to create a pocket of fuel for downhills but guess what happens if you park nose-down with 1/2 tank of fuel??? <sigh> More mods !!!

ChrisChris,

What a drag.

The gas is getting too hot...find the source of the heating and you have solved your problem...nothing new there.

Perhaps the round trip all of the unused excess gas gets is as it travels from the tank to the engine compartment and back to the tank again...over, and over, and over, and over... is heating it just enough so that finally the fuel pump is grasping a vapors.

An immersed pupp should help alleviate this problem, you might also address the source of the heating by insulating the supply and return lines from heat sources.

[Joe Guilbeau]

One other thought about the Vapor Lock situation.

You may have bought some gas with a higher Reid Vapor Index (RVI), check with the retailers in your area to find the gasoline of choice with the lowest Reid Vapor Index, something in the 6's.

Some independents might have slipped in some RVI rated gasoline in the 9's, to keep supply and demand in check.

[Wesdog]

On the subject of vapor lock, I posted this a while back and it's worked out well so far:

http://www.ifsja.org/ubb/ultimatebb.php?ubb=get_topic;f=2;t=019943#000007

I may add a small cooler inline with the return line to the tank to help remove any heat picked up by the fuel in it's round trip to the carb and back.

Wesdog

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/wesdog_avitar1.jpg

[fsj1978]

One of the problems I'm sure I had was the fact that the line from the top of the tank, down the side, to the front of the tank was aluminum, which is a wonderful conductor of heat!!!
I'e already had the idea of putting a fuel cooler in the system but wasn't, and am still not, sure how I'm going to do it. With my downhill fuel starvation problem that I've caused with the dang in-tank pump that some DUMMY put in the far *** end of the tank, I may wind up dropping the tank, putting a pickup in the front of the tank, run it to an external pump, thru a fuel cooler, and dump it back in the back of the tank right where the fuel pump pickup is. Then I could just turn the cooler pump on for either cooling if necessary, or I could use it for those extended downhills when I'd otherwise be sucking air... Either that or I'm going to put a small "surge / storage" tank in on the driver's side, just outboard of the frame rail. Use my in-tank pump to circulate fuel out of the tank, thru a cooler, then dump it into the surge/storage tank (how's THAT for a run-on sentance!!!) from there it would dump back into the main tank. Then I'd have a 2nd fuel pump (either in-tank or external) pull fuel from that storage tank and pump it to the motor, from there back to the storage tank...
I kind of like the first idea better just because it's more straight forward, and has less constantly used parts to die.
And to add one more idea into the mix, we've got an aux tank, if I put a valve into the first idea on the pickup side, I could use the one pump as both a "downhill" pump, and for a fuel transfer pump since I'm setup to run off just the main tank.
I've also had another idea or two running around, but those are the two that are coming to the front. hehe
Take it easy guys, and be well !!!

Chris

[Joe Guilbeau]

To add something else to the mix, here is what I have done on my Cherokee with the Holley Pro-Jection.

Keep in mind that this applies to the Analog systems (502) Series, I am not quite sure that the Digital configuratiions use the same parts.

I have the Aero 33 Gallon tank, and since it is "coffin-ish" on a down hill slant, the last 5 gallons of fuel is touch and go, just wanted you to know that you are not alone.

I put an Holley 801 Series "Red" pump on the cross frame member to protect it. This draws fuel from the Aero Tank.

Stainless steel lines run on the left side of the vehicle just inside the frame rails up to the engine compartment firewall on the drivers side.

Here I have the gas lines running to a gas filter (Holley PN 562-1) mounted on the left fender well, inside the engine compartment of course.

This feeds the Holley fuel pump (PN 512-103) that was included in the OEM package. The signal from the ECU that normally is used to drive the pump is routed to a relay instead, so that the ECU does not work that transistor as hard.

Excessive heat build up on my Analog ECU would otherwise result.

The Holley in-line fuel pump on the fender well feeds the Throttle body with the fuel pressure regulator, and mine is set for just about 14 PSI of fuel.

I use rubber lines inside the engine compartment, at the transition from undercarraige to inside the engine bay, on the theory that they will not transfer as much heat to the gas as might stainless or aluminum lines running inside the engine bay.

The exhaust manifolds are standard AMC fare and the exhaust is routed thru a standard crossover to a single pipe that feeds down the passenger side of the vehicle.

The return side gas line is 3/8" ID stainless steel, and the return pressure gauge reads between 0-1 psi for the return side.

The 801-series Red pump supplies positive pressure to push gas to the fuel pump that holley included in the system, at something like 7 PSI and can flow lots of fuel.

Holleys directions in their set up installation manuals are flat wrong, the fuel pump included in their package (PN 502-103) should NOT be located anynear the tank, but as close to the Throttle Body as practical.

Since I have positive pressurized gasoline supplying the pump on the fender well, and a relay supplying voltage to the fuel pump, there is no fuel starvation problem.

something that you may want to check is the voltage supplies to the pump during vapor lock situations.

That just might be the culprit.

Easy enough to check, if this is the case, just use a relay for the ECU to trigger, and now you will have full voltage to the fuel pump. Sometimes that transistor just will not supply enough juice to the fuel pump, especially if I understood you correctly and both of your pumps are at the rear undercarraige of the vehicle.

[The PIG Smith]

Joe, I read about half you post,
then I had to get some lunch, take a nap and I was able to read the rest! smile.gif

[fsj1978]

Joe, we *HAD* 2 fuel pumps under the vehicle just ahead of the cross member. The "D" systems use a relay to supply the fuel pump, not a transistor. I had the 2nd pump being fed from just a switch. I'm only using 5/16" return line, but I seriously doubt that's the problem. I'm also using rubber line under the hood. I haven't had vapor lock problems since putting the in-tank pump in it, but then again, we haven't done anything that would cause it to lock up, either.

Chris