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  #1  
Old July 9th, 2007, 16:11
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QRMTVI QRMTVI is offline
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Smokes after sitting...

For all I know, it smokes when Im driving too. '93 XJ 4.0 160k on the ticker. If I run it in park for several min, it starts to smoke blue out the pipe.

Im guessing stem seals, but likely rings too.

Any info on this? I think its common from what I hear.

Which, leads me to the question... Can the pistons be removed without having to remove the engine (to save the expense?) I also need a rear main seal, poor thing bleeds onto the e-pipe.

Id rather have this one fixed than to get a reman, the core has got to be good, it runs strong and good MPG, just several seal issues.

Thanks for any help!
Andrew
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Old July 9th, 2007, 16:16
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Re: Smokes after sitting...

Yes the pistons can be removed with out taking the engine out. You will have to remove head and oil pan and then use a ridge reamer to remove the ridge that develops at the top of the cylinders. If you don't you could break ring lands off the pistons.
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Old July 9th, 2007, 16:18
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Re: Smokes after sitting...

Provided the block doesn't need work, it is possible to do a rebuild without removing it.

I'd try the stem seals first - the seals are "umbrella type," so you don't even need to pull the head. Just get an "air hold" (threads into the spark plug hole and allows you to pressurise the cylinder to keep the valves closed) and carefully replace the seals. I find it helps to soak them in clean oil for at least fifteen minutes before they go in - that makes them pliable, and will help them seal more quickly.

If that doesn't do the job, then you pull the oil sump, cylinder head, and then you can pull the pistons for a re-ring. If you're going to hone the cylinders, I /strongly/ /recommend/ that you pull the crankshaft as well. You can probably rinse the filings and stone grit off of the crank if you're careful and thorough enough, but I don't like to take chances. You do have to pull the transmission (at least six inches back, anyhow) to pull the crankshaft. You can drop the crank with the flywheel/clutch or flexplate/torque converter attached, if you're not going to change anything.

Valve guide seals can be done in an afternoon. In-place re-ring can be done in about two days (one, if you push it - but I don't like to rush through these things... I take my time.)
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Old July 9th, 2007, 16:27
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Re: Smokes after sitting...

I dont have the time to do these proceedures, but I wanted to know what was involved so I am at least educated when I look for a mechanic.

Which leads me to... What is the most likely thing the mechanic will want to do? Pull the engine and put it on a stand, or do it in-place?

I know just to pull an engine is a few extra hundred dollars, and theres only 42 dozen things that can go wrong if you make 1 little boo boo. (not that anyone ever made a mistake or anything...) :-)

Thanks for the help! Ive debated getting another vehicle, but... This one is paid for and I know the drive train, engine, tranny, etc.. are in good condition. You know what happens when you go used car shopping... you dont always get a good rig.

Thanks agn!
Andrew
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  #5  
Old July 10th, 2007, 09:37
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Re: Smokes after sitting...

Before you get too far, check that the vacumn line to the rear of the valve cover is clear. If that's plugged up, it can make blow-by and rear main seal leaks a tad worse. Just pull it off at the cover while it's running and see if it's got vacumn on it.
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Old July 10th, 2007, 12:21
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Re: Smokes after sitting...

You definitely need to replace the valve stem seals but also check the valve guides for wear and run a compression check to check the rings.
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Old July 10th, 2007, 14:18
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Re: Smokes after sitting...

If you drive it and get it warm, then sit in the drive through at your local McDonalds and by the time you get to the window you see smoke, it is valve guide related, not ring related. New seals may help but the real solution is to do a valve job and have them ream the head and sleeve the valve guides.

Rebuilt heads are not the way to go. 99% of all rebuilt heads simply have the guides knurled and that will last about 15k miles and it will start smoking like a pig.

Remember that smoke at an idle where the vacuum is highest means valve guides. Smoke under load means rings.
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Old July 10th, 2007, 19:53
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Re: Smokes after sitting...

Quote:
Originally Posted by old_man
Remember that smoke at an idle where the vacuum is highest means valve guides. Smoke under load means rings.
Gotcha, didn have that tid bit of info in my intel bank. :-) Good info, Ill first op for a full head job... cause we all know, a head job is a good thing to have.

I still need the rear main worked on too, Ill likely have to do this a piece at a time due to $$$.

Thanks for the great info from everyone!

Oh, BTW... Ive already replaced all the CCV hoses and fittings a while back. No change in operation so it sure looks like the head then.

Thanks agn!
Andrew
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