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post #1 of (permalink) Old 06-29-2001, 04:10 PM
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valve stem seal

1988 Wrangler 258 / BBD --114,000 miles-I believe that I may be faced with a leaky valve stem seal in cyl #4 and /or blown head gasket . Here is some info -- Dry Compression test results done by dealer : 110,155,150,75,100,150 . This winter , I could see dark sooty smoke from exhaust at startup . This would disappear as engine warmed up. I don't believe that the smoke was the traditional blue-grey oil smoke . Also, I seem to be losing coolant , as I must add one quart / 100 miles . I do not see any coolant leaking on ground, radiator , nor at the hose connections. I am not aware of any white puffs from the exhaust , though I am looking for the white puffs. Because I was seeing much oil in the airbox, I thought that I may be facing worn rings with the much discussed blowby. I did the bypass of the air breather from rear of valve cover to a jug last week . I am getting 5 tablespoons of oil in the past 60 miles . Not as bad as I anticipated . There is plenty of suction at the PCV valve into front of valve cover , but the vacuum does not appear at the rear valve cover grommet . I replaced the grommets 2,000 miles ago along with valve cover gasket and all seems very snug. Any comments ? Can anyone provide experience with replacing the valve seal ? Did you use the rope trick or use a compressor to prevent the valve from falling into the cylinder? Is this a dealer only part ? Do I just have to worry about the Intake valve seal ? The Jeep seems to idle fairly smoothly . I do not know what a perfect engine would feel like upon acceleration and I have no gold standard against which to compare this used engine.I feel like I am just guessing at what performance should be when perfect . MPG = 11.

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post #2 of (permalink) Old 07-02-2001, 08:34 AM
 
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Re: valve stem seal

Your compression test is telling you that 3 of the six cylinders are not up to par. They should all be within about 10lbs of each other. Try a wet compression test. Seals only help keep oil from running down the valve stems into the engine. They do not help with the compression. Since you are losing coolant and the oil issue I would suggest that your head gasket is crapping out or the head maybe warping. A wet compression test that reveals numbers that are not much better also points towards the head/gasket. You can certainly do the valve seal replacement. The rope trick is best for beginers. Valve seals should be found at most parts stores. Do all the seals. I don't think that is going to help your problem.

Pigpen
76 CJ5 360/T18A/Bronco gear D20/D30 big brake disc, locker/D44 big drum working on disc/ factory slip/4inch lift/33's/6000lb winch/All Fiberglass/electric fan/full cage/ appetite for MUD
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post #3 of (permalink) Old 07-02-2001, 09:34 AM
 
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Answer to 100 questions

You are just one of a hundred who have come here wanting advice concerning blow-by, low compression, exhaust smoke, poor performance, etc.
All say, "How can I fix it?"
A couple of years ago I made a post here with the above subject title, "Answer to 100 questions"... and the 'answer' is ... hey, in a lot of cases its just plain ole' worn out!
It's a sad fact, but true.
Somehow a lot of folks get it into their heads that since a Jeep will practically last forever. They hope an engine with 100,000 miles on it will just keep on a go'in.
Not so in most cases I'm sorry to say.
Or isn't that what the dealer who ran the compression test tell you?
Start thinking swap or rebuild ...



JAF
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post #4 of (permalink) Old 07-02-2001, 09:50 AM
 
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Re: Answer to 100 questions

I think personally its just a case of "pick of the litter" My jeep was an 87 Yj with the 258, it was one of the first couple thousand YJs ever made! It ran until 230,000 miles No problems(except the transfer case was factory swapped after 5,000 miles). After 230 miles, my mechanic destroyed my jeep! It was running so well too.... Ever since I replaced the 258 with a newer 258, it has never been the same, It leaks oil, cracks valve covers, has exhaust leaks, it doesnt "get along" with my carb anymore. you know, if you replace the engine, make sure you replace its friends too(especially if your enigne is that old). i have, since january of this year, added: headers, a new valve cover, rebuilt that carter piece of crap(cause its the only street legal carb in cali I have found for the wrangler), and it is still running bad.

so, like I said, pick of the litter, 230 and ran great,
9 thousand on new motor, running like crap..
-Ben

1948 CJ-2A - R.I.P.; Rest in Progress...
1987 Wrangler - 4-inch Procomp, Rancho Shocks, Arb Snorkel, Con-Ferr Rack, Pacesetter Header
1994 Grand Cherokee, Stock, 30-inch BFG All-Terrains
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post #5 of (permalink) Old 07-04-2001, 12:09 AM
 
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Re: valve stem seal

I just replaced mine a couple of months ago or so. I used air and replaced all 16 of them. Air is the BEST way to do this job and cant imagine doing it any differently. The symptoms of bad valve stem seals are...1st start of the day, no smoke. Let it run for a while and shut it down, then start it after about 15 minutes or so...if you get blueish smoke at first then goes away then probably valve stem seals. If you let it set for hours and start it then you should see no smoke. As mentioned in a previous reply, the seals prevent oil from running down the valve stems into the cylinders. If the vehicle sits for a while then any oil that ran down the stems into the cylinders will have gone past the rings back into the oil pan...hence no smoke. Thats also why you get smoke after the jeep has only sat for a short time...because the oil has run down the stems but hasn't had time to get by the rings yet.

Hope this helps...it has nothing to do with poor compression...

78 CJ5 w/360
"measure it with a micrometer, mark it with chalk, and cut it with an axe"
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