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Head or entire engine rebuild? Smokin
Topic Started: Sep 11 2012, 04:42 PM (1,189 Views)
North Plains Drifter
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My 90 Metro smokes bad after coasting a bit, I suspect bad valve guide seals. I took a compression check and I'm between 155 & 165 for all 3 cylinders. My question is can I get by with just a head rebuild, or is it going to need a bottom end too? I'm really thinking of just putting some new vavle guide seals in and go with it, it runs great otherwise.

Thanks all!
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Johnny Mullet
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Valve seal will only make it leak on initial startup. Your oil rings are clogged up with carbon like the rest of the engine. Compression is fair, so try running Marvel Mystery oil in the engine oil or using seafoam in the oil and you might get lucky after a few thousand miles..
Edited by Johnny Mullet, Sep 11 2012, 05:57 PM.
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pdqrunner


I did just the top end and it pushed so much oil through the rings I got 35 miles to a quart of oil. In three days the head was coated with a gold deposit. No smoke just burnt oil. Do the pistons and rings, bearings and oil pump. Its cheap. The motor does not need to come out of the car.
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Johnny Mullet
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pdqrunner
Sep 11 2012, 06:38 PM
I did just the top end and it pushed so much oil through the rings I got 35 miles to a quart of oil. In three days the head was coated with a gold deposit. No smoke just burnt oil. Do the pistons and rings, bearings and oil pump. Its cheap. The motor does not need to come out of the car.
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Johnny Mullet
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So do not rebuild the head alone if you decide to tear into it early. I suspect with that compression, you might get a year or more out of it while cleaning the internals before the inevitable or you might get lucky if you get the rings unstuck.
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North Plains Drifter
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Hmm, I could be wrong, but I was assuming valve guide seals because I've had a simalar experience with my Jeep V8... The smoking just started getting really bad lately, bad as being a huge blue smoke screen behind me! Call me the Bat Mobile! It only happens on real long down hill roads where I don't touch the throttle, then when I do, poof! Smoke screen! It also just past emmisions. There is no residue on the back ot the car either.

Soooo, with what you guys are saying, you don't think just vale seals will cure it? Darn! Well that's why I posted because you guy know more than me! ^o)
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Memphis metro


The good news is, its the easiest engine you will ever work on.
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North Plains Drifter
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pdqrunner
Sep 11 2012, 06:38 PM
I did just the top end and it pushed so much oil through the rings I got 35 miles to a quart of oil. In three days the head was coated with a gold deposit. No smoke just burnt oil. Do the pistons and rings, bearings and oil pump. Its cheap. The motor does not need to come out of the car.
So are we talking new bearings, oil pump, pistons, rings, with just a hone job. I didn't know you didn't have to pull the engine. How do you get the bearings w/o pulling the crank? I'm not familar these engines.
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Memphis metro


He was talking about the rod bearings. Main bearings are usually good.
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idmetro
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North Plains Drifter
Sep 12 2012, 10:31 AM
quote]So are we talking new bearings, oil pump, pistons, rings, with just a hone job. I didn't know you didn't have to pull the engine. How do you get the bearings w/o pulling the crank? I'm not familar these engines.
It is also possible to change the main bearings without pulling the crank. The issue is that "new" aftermarket bearings are not typically as precise as the originals so even though you got "new" bearings your clearances could be worse. I have traded "new" bearings in where they were a closer tolerance than the existing set by loosening all the main caps then spinning the crank by hand while applying a bit of pressure to the bearing shell with a tupperware orange peeler (plastic poker type thing), then reversing the process to get the new ones in. Double check clearances with plastigauge, it won't tell you if the crank is out of round but at least you will know it isn't too tight/loose...

Best way of course would be to pull the crank and have it ground to match precisely with the "new" bearings. Good Luck!
Edited by idmetro, Sep 12 2012, 11:15 AM.
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Old Man


quickest, easiest and cheapest is to try replaceing the valve stem seals. I would do this first and see what happens.

I, also, have had the experience of -- off the gas down a long hill and at the bottom a big puff of smoke when I hit the gas---and it was valve seals.
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North Plains Drifter
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It has 150k on it, would I need to do main bearings? Not opposed to a full rebuild, just trying to see if it is nessecary to bet another 50k + out of the engine.
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Coche Blanco
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Do what old man suggests.
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North Plains Drifter
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Coche Blanco
Sep 12 2012, 12:08 PM
Do what old man suggests.
Sorry, would that be JM? The Marvel oil or Sea Foam idea?
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Coche Blanco
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No, the post above yours that says, "quickest, easiest and cheapest is to try replaceing the valve stem seals. I would do this first and see what happens."

Replace the valve stem seals and see what happens. Why knows, you might get lucky!
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