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post #1 of (permalink) Old 12-27-2001, 06:08 PM
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Compression test results

1=130 2=150 3=150 4=145 5=150 6=10(yah just 10!)
by the way...'88 yj 4.2L weber carb 4" lift, 33's, auto tranny(stock) everything else stock. talked to a few mechanics(certified) and they all said that it's the valves. I put a little oil in the #6 cylinder and the compression stayed the same. There is a little knock, but it seems like it's coming from the bottom of the engine. a machinist said that it could be the connecting rod bearing. Any ideas? I'm getting ready to take off the valve cover and check out the valves. But also, I don't see why there is oil all over the engine and tranny. I have my rear pcv plugged, could this be a part of the problem? Thanks for the help.
Tim

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post #2 of (permalink) Old 12-27-2001, 06:24 PM
 
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Re: Compression test results

It sounds like a valve. You will have to pull the head, not just the valve cover to check the valves. The knock could be from the valve, lifter or a rod/main bearing.

The oil could be excessive ring blow-by. Why did you plug the PCV? It's there to help you. By plugging it you build up pressure in the crankcase and it WILL blow out somewhere. Bad blow-by will make it worse.

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post #3 of (permalink) Old 12-27-2001, 07:49 PM
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Re: Compression test results

Jeepin_Tim-

If #6 did not come up with oil put in the cylinder, it sounds like the valves, but if it is blowing oil out of the PVC valve or around the PVC, it sounds like blow by. The #1 cylinder at 130 is not good. The reality may be that you are having problems with both the valves and blow by. I just rebuilt at 93 4.0 114K for both of the above.

Good Luck!
Kriss

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post #4 of (permalink) Old 12-27-2001, 08:10 PM
 
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Re: Compression test results

Most likely valves, could be cam, lifter. Ask one of those (certified) mechanics to do a cylinder leak down test on cylinder #6. That should direct you somewhat, if they hear air out the carb, intake valve, air out the exhaust, exhaust valve. etc...
Redo your PCV system, it plays an important role.
The lower sounds shouldn't be too bad, but see how it sounds when the upper half is running correctly.
Clean your engine (the right way) and then see where the oil comes from. That will make that alot easier.


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post #5 of (permalink) Old 12-27-2001, 08:11 PM
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Re: Compression test results

The PCV being plugged is the entire reason why there's oil everywhere. The pressure in the crankcase has nowhere to go, so it blew out the weakest link, that being the valve cover gasket.

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post #6 of (permalink) Old 12-28-2001, 01:19 PM
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Re: Compression test results

Well thanks for all the help. I talked to anther mechanic and he said that it probably is a valve and blow-by. I now feel stupid for pluging the friggin pcv but then again, doesn't the front one suck up and the back one go in? Oh well, guess I'm stuck 150 miles away from home until I fix the problem. Think I could get home by just replacing the valve and waiting on the blow-by? What does it take to fix a blow by problem? Thanks for the responses.
Tim

post #7 of (permalink) Old 12-28-2001, 09:42 PM
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Re: Compression test results

As I posted before, your crankcase overpressured. Most of the oil shot out the dipstick tube, but anyway. If I were you, stuck away from home, here is what I would do. Pull the plugs and value cover. Rotate the engine to get #6 up to top-dead-center. Use a wire down the plug hole or finger on the plug hole. Check the value action. Maybe you can just adjust the lifters to get them working. Run the engine and see how it sounds. If the noise still seems bad, put STP or some other Vicosity Index Improver in the oil. Go to 90w if you have to to quite it down. Then tenderly drive it home. What have you got to lose? E-mail me at [email protected] if you get stuck or I can help. I will check in tomorrow, but I am going out sat. night.

85 CJ7,Chevy LT-1,700R4,NP208,4 1/2 lift,33's
77 Blazer,350 Cowl Induction,TH350,NP203 8", 33's

post #8 of (permalink) Old 12-28-2001, 09:53 PM
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Re: Compression test results

Check your E-Mail. I sent my phone number if you need to call.

85 CJ7,Chevy LT-1,700R4,NP208,4 1/2 lift,33's
77 Blazer,350 Cowl Induction,TH350,NP203 8", 33's

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