Running Hot!

[Danny Armstrong]

I have a 88' Grand Wagoneer, 155 K miles. When towing, the engine heats up, it hasn't boiled over or blown anything yet. I have to turn off the AC to conserve cooling capacity. Also, the thing has never had any power when towing ( I tow boat / trailer rig about 3,000 lbs. ).

Here's what I've done so far:
New radiator, water pump, fan clutch, belts, hoses, thermostat ( 195 deg. ), 50/50 mix antifreeze and distilled water, trans. cooler.

The thing runs great and never heats up now when not towing. What other things could cause this? The engine is original ( heads and valves re done at about 90k ). One other thing going on, the guage shows no oil pressure once the engine heats up to normal temp., but there is no knocking or smoke or excessive oil loss?

With all that I have done to this thing I am just at a loss. If anyone has other ideas, they would be greatly appreciated. This is my second Jeep. I had a 1979 Cherokee for 14 years, and have had this one since 92'. :confused: :confused:

[Bob Barry]

Have you replaced your catalytic converter, or is it the original? A clogged cat will kill your power, causing you to put your foot in it more to feed the engine more fuel, which will release more energy that the cooling system will have to absorb. That, combined with improper timing, can boost your water temps.

A frozen heat-riser valve will route the exhaust from one cylinder bank through the intake, which will raise intake charge temp and overall engine coolant temp.

A clogged A/C condensor will restrict airflow and reduce the cooling efficiency of the radiator.

Is your fan-clutch a heavy-duty thermal unit? That can help a big bunch, even on the highway (believe it or not).

A vacuum leak will lean out the fuel mixture, as will an inoperative or incorrect EGR valve; leaner mixtures make the engine run hotter. How are those components?

It's more likely a lot of little things than one big thing. My '88 used to run hotter on the highway than I would have liked; after a lot of little changes, it came down to run below 205ºF under the worst conditions. Now with a 4-row radiator, barely goes above the top of the blue.

[Lindel]

At a guess, I'd say that the catylitic converter is getting badly plugged up, and needs to be replaced.

Take it down to a reputable muffler shop, and have them look at it.

[Danny Armstrong]

Thanks for the info. I have thought of some of these things too. I have wondered for some time if the converter is plugged. I had a 2150 carb that was running rich for years until I replaced it ( took three rebuilds to get one that would run ). The timing thing may also be a problem. The engine also pings ( detonation ) when it gets hot, never does when cool. Possibly too much advance at highway speed? I don't think I have any vacuum leaks but I may disconnect some of the junk anyway which may cure some leaks if there are any. On my 79 Cherokee, I stripped ALL the crap, went to headers, edlebrock intake, edlebrock carb, manual choke and never had any problems again. I have been trying to keep this one legal, but am now loosing my patience!

Thanks again,
Danny
Midlothian, Va. wishing I was driving down Hatteras Island, NC.

[Oso]

One other thing going on, the guage shows no oil pressure once the engine heats up to normal temp., but there is no knocking or smoke or excessive oil loss? Could be your sending unit. Could be your oil breaking down in the heat, or your oil breaking down and causing the heat. Try a different brand and or viscosity of oil. There are a couple brands out there that break down on me everytime. Either way, it is a serious problem and needs to be taken care of. A reman ain't cheep.

[Danny Armstrong]

OSO, on the oil thing, I use either Pennzoil or Castrol 10/30. I just recently changed the oil using Penn and added a quart of Lucas oil stabilizer, for the heck of it.

I do want to change the sending unit, to eliminate that possibility ( the guage does do some strange things ).
Has anyone ever seen the oil pump go bad in a 360? I realize that wear on the crank and rod bearings will reduce oil pressure, but wouldn't the engine be doing some funny things with zero pressure, and what about the hydraulic lifters? One thing I forgot to mention, when the heads were done I installed an RV cam and performance lifters, which required a double roller chain and sprocket which is set at top dead center instead of the original which is set at 4 deg. advance, if memory serves.

Thanks
Danny

[Don S]

Danny Armstrong.. I'll bet you still have some pressure because of the hydraulic lifters. Bob and the guys sure give out with the good ideas. The link below has a few more thoughts about cooling systems.. ;) ... ds..

http://groups.msn.com/ATexasOklahomaJeepClub/ouraycotopic.msnw?action=get_message&mview=0&ID_Message=199&LastModified=4675375741189581937

[Danny Armstrong]

Wow, I just want to thank everyone for their response. I've been reading some of the info on this site for a while from time to time and I'm glad I decided to join in. Many of the problems I've seen described here, I have definite experience with, with one or the other Jeeps. I'll try to give my 2 cents when I can, but it looks like we got some real Jeep experts on this board!

Thanks again,
Danny

[ChrisCollege]

Another often overlooked cooling issue is the fan shrowed. I put in a brand new Jasper 360 and changed the fan clutch but it was still running hot, knowing that the radiator was spent I put a new stock radiator in but still had problems until I installed the factory fan shrowed. Hard to believe the fan shrowed would make such a diffence but it did. Especially at low speeds under load.

[NomadJack]

I would definately put my money on a plugged cat. Take it to Meineke or Midas (or some other muffler shop) and have them do a back-pressure check on it. If you've been running rich for a while, chances are you've burned your cat up. Mine reared its ugly head while towing a trailer from Tulsa to Seattle and I limped into Boise at 45 mph for the last 100m. 2 hours and $175 later I was back on the road doing a happy 65.

[joe]

Originally posted by Danny Armstrong:
I have wondered for some time if the converter is plugged. I had a 2150 carb that was running rich for years until I replaced it. With that said, I too vote for the plugged cat.