wet/dry comp test analysis

[SlickKipper]

How, if at all, would a wet/dry compression test help me analyze the knock i got comin' from my engine? If the knock wasn't piston slap, and the compression test checked out ok in both wet and dry modes, would that possibly point to an asymmetry in the crank shaft?

How y'all doin'
SK

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1989 Grand Wagoneer, 32,000 original miles, K&N air, Flowmaster 70 Series muff, hi-flo cat

My Wagoneer (http://hometown.aol.com/hebbarts/myhomepage/photo.html)

"ahh, i love the smell of 11 year old differential oil in the morning"

[joe]

A comp test is just going to tell you the condition of your rings and valves. 360's generally aren't prone to pistion slap especially on a motor with what...32,000 miles? You "sure" that's not 132,000?
Is the knock a real "knock" sound or more of a "tick" sound?
Only thing I can think of is spark knock/detonation maybe from an inop EGR valve or timing too far advanced. If it's more of a tick I'd look for an exhaust leak especially around the air injection rails/fittings. They're very prone to rust, look "closely" at them. If it's a real honest to goodness metal-to-metal thunking knock noise I'd suspect you've got bearing going south.
Get apiece of vac hose and put one end to your ear and run the other end over the entire motor [except the fan http://www.ifsja.org/ubb/smile.gif ] and look for valve/lifter/rocker arm/exhaust/ bottom end etc noise. You should able to isolate it a bit better that way.
-joe

[SlickKipper]

Joe-
The sound is really a metal clunking knock. Not at all tick-like. The knock is most pronounced when the engine is cold. Timing checks out ok. I too I wouldn't expect my rings to be bad, due (as you said) to the low (and legit) miles, and the fact that an analysis of the overall manifold vac revealed good health. I am aware that the PO had a "dead cylinder" repaired, and i'm pretty sure that the rockers and rods in that particular cylinder had been replaced. Not sure if the piston/rings/or bearings were replaced, but i suspect that this knock has something to do with that situation. I'm wondering if maybe after that cylinder was fixed, the PO didn't properly break it in, as one would after a rebuild, and maybe that caused premature wear of the replaced parts, presumably the bearings. Anyhow, I've heard a lot about the earhose deal, and I'll locate the problematic cylinder next. If it IS a shot bearing, can those be replaced w/o removing the engine?

-Kip

[AcelaTech]

<BLOCKQUOTE>quote:</font><HR>Originally posted by SlickKipper:
Joe-
The sound is really a metal clunking knock. Not at all tick-like. The knock is most pronounced when the engine is cold. Timing checks out ok. I too I wouldn't expect my rings to be bad, due (as you said) to the low (and legit) miles, and the fact that an analysis of the overall manifold vac revealed good health. I am aware that the PO had a "dead cylinder" repaired, and i'm pretty sure that the rockers and rods in that particular cylinder had been replaced. Not sure if the piston/rings/or bearings were replaced, but i suspect that this knock has something to do with that situation. I'm wondering if maybe after that cylinder was fixed, the PO didn't properly break it in, as one would after a rebuild, and maybe that caused premature wear of the replaced parts, presumably the bearings. Anyhow, I've heard a lot about the earhose deal, and I'll locate the problematic cylinder next. If it IS a shot bearing, can those be replaced w/o removing the engine?

-Kip<HR></BLOCKQUOTE>

Actually, you dont even have to remove the crank to replace the bearings. They can be replaced one-at-a-time from the bottom end just by removing the oilpan. You may have to remove the spark-plug from the head to facilitate moving the piston upward to remove the bearing. By removing the spark plug you allow for the expansion of air above the piston so the piston will move easier. However, I suspect that you will want to check out the crank REAL CLOSELY, because installing a new bearing in place of a ruined one that may have possibly chewed up the crank is only gonna ruin another bearing.

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DON

1988 GW mostly stock, &lt;---Wifey's truck (won't let me "fix it up")

1971 J-4000,Rhino Grille
360 CID 8.5/1 ratio 2v, 245 HP, 365 ft/lb
T-18A, Dana 20, PTO, DANA 44 (Front/Rear)
Soon to be torn down for Resto

78 GW (parts truck)
360 4v Th400
Dana 44 F/R http://www.j-trucks.freeservers.com/

[This message has been edited by AcelaTech (edited November 21, 2000).]

[This message has been edited by AcelaTech (edited November 21, 2000).]

[SlickKipper]

Don-
If there's an irregularity in the crankshaft journal, I understand I'll be looking at a regrind, but (and forgive me for my lack of knowhow) will i have to take the engine out to remove the crankshaft? Also, do you know anything about having an "oil analysis." Could that be a quicker way to determine the source of wear?

-Kip

[This message has been edited by SlickKipper (edited November 21, 2000).]

[joe]

Kip, you can do it all through the bottom but I really recommend you get an original or repop of the factory shop manual first.
You'll have to pull the radiator prolly to get room to work to get the crank balancer etc off.
I'd pull the suspect rod bearing off first though and look carefully at it for scars, copper showing through. And if it looks ok do the plasti-gauge thing to see what clearance you have(it's in the TSM). If it's out of spec which is pretty likely or the bearing inserts are rough the crank journal is too prolly. If you get the crank re-ground be sure to change all the rod and main brearings to the new specs the crank has been ground too. New undersize main/rod bearing kits are easily avail and not very expensive.
Oh...if the book doesn't meantion it but it should, use assembly lube on the bearings when screwing this all together.
-joe

[AcelaTech]

<BLOCKQUOTE>quote:</font><HR>Originally posted by -joe:
Kip, you can do it all through the bottom but I really recommend you get an original or repop of the factory shop manual first.
You'll have to pull the radiator prolly to get room to work to get the crank balancer etc off.
I'd pull the suspect rod bearing off first though and look carefully at it for scars, copper showing through. And if it looks ok do the plasti-gauge thing to see what clearance you have(it's in the TSM). If it's out of spec which is pretty likely or the bearing inserts are rough the crank journal is too prolly. If you get the crank re-ground be sure to change all the rod and main brearings to the new specs the crank has been ground too. New undersize main/rod bearing kits are easily avail and not very expensive.
Oh...if the book doesn't meantion it but it should, use assembly lube on the bearings when screwing this all together.
-joe<HR></BLOCKQUOTE>

Uh...yeah...what he said! http://www.ifsja.org/ubb/smile.gif

Wouldn't worry about oil analysis to much. You already have a good idea what the prob is. I would personally try checking out the bearing.



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DON

1988 GW mostly stock, &lt;---Wifey's truck (won't let me "fix it up")

1971 J-4000,Rhino Grille
360 CID 8.5/1 ratio 2v, 245 HP, 365 ft/lb
T-18A, Dana 20, PTO, DANA 44 (Front/Rear)
Soon to be torn down for Resto

78 GW (parts truck)
360 4v Th400
Dana 44 F/R
http://www.j-trucks.freeservers.com/

[SlickKipper]

So if i get a new crankshaft and connecting rods, can i still use the old pistons and rings (assuming they're ok)?

-Kip

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by SlickKipper:
So if i get a new crankshaft and connecting rods, can i still use the old pistons and rings (assuming they're ok)?

-Kip<HR></BLOCKQUOTE>

Kip, if your compression readings were good I would leave them alone. I'm thinking here that for now you just want to fix the knock?
If you go as far as replacing pistons and rings you'd be better off just pulling the motor and get it hot tanked, honed, new cam bearings pressed, freeze plugs etc and do a complete rebuild.
Becareful ya don't get caught up in "well while I've got this apart I may as well"...next thing ya know a minor repair turns into a major project. Sometimes that's a good thing to do but a lot of the time it's uneccessary. Hard call to make sometimes http://www.ifsja.org/ubb/frown.gif
If it was me I'd fix the knock and then see where I was at. If the knock is gone and everythin seems to be working...I'd call it good.
-joe

[andy d]

kipp. none of my 360s ever had this, but the willys f head 6 and a ford 223 6 both had several of them, loose wrist pins. they sound kinda like a bad rod bearing. they arent generally fatal. have someone who has been a mechanic 30 yrs or so diagnose it. btw,rod knocks generally get worse quick. you have been desribing this noise for about 3months or so. if you have been driving the rig all that time, its prolly not a rod, it woulda thrown by now. http://www.ifsja.org/ubb/biggrin.gif

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'88 gwag,pure stock

[SlickKipper]

Barring the possibility of a loose wrist pin, what size a' micrometer should i get for inspecting the crankshaft journal?
0-1"? 1-2"?

Kipster

[andy d]

Slick, iwould say at least a 2" possibly larger. a visual inspection would tell a lot too. a newly ground crankshaft journal is pretty shiny,like a mirror. a worn out journal will have a scuffed look to it. lotta times there will be grooves in it. look at the bearing surface too. if you can see copper you have a problem good luck

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'88 gwag,pure stock

[SlickKipper]

andy,
i think we gotta' consolidate this coversation...

the crankshaft journal is btw 2 and 3"?

kip

[andy d]

Slick, i had a main bearing cap off briefly. the scarring of the journal and the bearing surface told me what i needed to know. the journals appear to be around 2".they could be just under or just over. i didnt measure them. if a bearing is worn out,there is excess clearance between the journal and the bearing. basic physics, if the pressure is constant and volume increases, then pressure is decreased. thats why i was asking about oil pressure on the other post. your noise has piqued my curiosity. i dont think its life threatening. heck it could be something like the pickup tube getting in the way. good hunting and good luck http://www.ifsja.org/ubb/smile.gif

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'88 gwag,pure stock

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by SlickKipper:
Barring the possibility of a loose wrist pin, what size a' micrometer should i get for inspecting the crankshaft journal?
0-1"? 1-2"?

Kipster<HR></BLOCKQUOTE>

Kip, you'll need a 2-3" mic. The mains are in the 2.7+" range and the rod journals 2.0+"
Drop me a line direct if you want the exact specs and I'll look'em up.



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Regards,
-joe
63 2-dr Wag, 73 J-4000, 82 CJ-8

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by SlickKipper:
Don-
If there's an irregularity in the crankshaft journal, I understand I'll be looking at a regrind, but (and forgive me for my lack of knowhow) will i have to take the engine out to remove the crankshaft?<HR></BLOCKQUOTE>

Others have said that this could be done with the engine in the truck. Maybe so, but I'd like to see the trick of how you get the flexplate unbolted from the crank, and how you get the crank past the plate that goes between the block and the flexplate.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[SlickKipper]

What's a pickup tube? (Got a factory service manual coming in 7-10 days if it's too much trouble to explain.)

SK

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by BobBarry:
Others have said that this could be done with the engine in the truck. Maybe so, but I'd like to see the trick of how you get the flexplate unbolted from the crank, and how you get the crank past the plate that goes between the block and the flexplate.

<HR></BLOCKQUOTE>

You do have to pull the trans to get the crank completly out but shouldn't have to to just insert new bearings.



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Regards,
-joe
63 2-dr Wag, 73 J-4000, 82 CJ-8

[Gladi8r]

<BLOCKQUOTE>quote:</font><HR>Originally posted by SlickKipper:
What's a pickup tube? (Got a factory service manual coming in 7-10 days if it's too much trouble to explain.)

SK

<HR></BLOCKQUOTE>


Pick-up tube is the tube that runs from the bottom of the oil pan to the oil pump. It is about 3" round and has a screen on the bottom of it.

The Trans will have to be removed if you need to replace/regrind the crank, however if the crank is good the bearings can be changed without removing the crank.

Hope this helps explain things.


------------------
DON

1988 GW mostly stock, &lt;---Wifey's truck (won't let me "fix it up")

1971 J-4000,Rhino Grille
360 CID 8.5/1 ratio 2v, 245 HP, 365 ft/lb
T-18A, Dana 20, PTO, DANA 44 (Front/Rear)
Soon to be torn down for Resto

78 GW (parts truck)
360 4v Th400
Dana 44 F/R
http://www.j-trucks.freeservers.com/

[SlickKipper]

WELL...

In light of what the many of you have said (about low oil pressure being the result of a worn rod bearing) I'm really thinking it IS something else causing the knock. I'm truely a neophite at this mechanicry bit, so I was thinking that when folks hinted at the possibility of it not being a bad bearing, maybe they were thinking MAIN bearing instead of ROD bearing/journal.

Anyhow, I'll be working on the "El Riggo" this weekend, and what I'll do is:
1.) hook up a mechanical pressure gauge to verify that I do indeed have good oil pressure, as indicated on the dash gauge, and
2.) spring for a deluxe MECHANICS STETHOSCOPE (and who knows, maybe even a sphygmomanometer!) and thoroughly hear fr' wher'd'noise's comin' fromp.

Figure after all the advice y'all have provided, it's my turn t'put it t'use. I will, of course, be sure to keep a'postin' once I got more info to add to the equasion.

'preciate it fellas

Kip