# does this call for a rebuild?



## daveh70 (Sep 4, 2008)

My car has the original 389 and to my knowledge has a standard rebuild in 2003 but I don't know the milage. I've had the car 3 years. Currently upon start up there's blue smoke. The plugs were oil fouled badly after a year period with roughly 500 miles driven during that time. I know it's eating oil but not sure the amount. The shop is suggesting a rebuild and maybe it needs piston rings or valve guide replacement. 

However, a friend of mine says to write down the current milage. If I can go at least 700 miles and the car eats up a quart of oil max then I'm fine. If it uses up more then he would do a rebuild. Would you agree with this plan? Thanks


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## BearGFR (Aug 25, 2008)

arty:


daveh70 said:


> My car has the original 389 and to my knowledge has a standard rebuild in 2003 but I don't know the milage. I've had the car 3 years. Currently upon start up there's blue smoke. The plugs were oil fouled badly after a year period with roughly 500 miles driven during that time. I know it's eating oil but not sure the amount. The shop is suggesting a rebuild and maybe it needs piston rings or valve guide replacement.
> 
> However, a friend of mine says to write down the current milage. If I can go at least 700 miles and the car eats up a quart of oil max then I'm fine. If it uses up more then he would do a rebuild. Would you agree with this plan? Thanks


Most of the time, general statements like those are either wrong, or at least don't tell the whole story. I'd recommend some more research before starting a rebuild - if nothing else to try to identify where the problem is. Smoking on startup (if it clears up after that) to me sounds more like valve giudes than it does rings, but it's not conclusive. Recommend that you do both a compression test and a cylinder leak-down test. If you do your own compression test, use a good quality gauge, remove all the spark plugs, and block the throttle open while testing each cylinder. Do it "dry" first. You're looking for consistency across all the cylinders more than you are the absolute reading, but both do matter. If you find one or more "low" holes, then test those again after putting a couple of good squirts of oil in through the spark plug hole. If the pressure increases significantly wtih the oil, that's a clue the rings aren't sealing. If nothing changes, then it's leaking past the valve guides (or 'worse'). 

The more you know about what's going on inside the motor, the better prepared you'll be to decide how to deal with it.

Bear


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## jetstang (Nov 5, 2008)

It may just need valve seals. Sounds like a plan. If all you are doing is cruising the car and it runs then it may be fine. Just know what you got and swap the plugs more often. My 389 ran great, just blew smoke when you romped on it, I took it out and it was wore slap out. Mine was pistons and rings, but the plugs looked good. Yours sounds like heads. You may just get the heads redone, then look at the pistons while you got the heads off and decided from there on bottom end work.


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## freethinker (Nov 14, 2009)

daveh70 said:


> My car has the original 389 and to my knowledge has a standard rebuild in 2003 but I don't know the milage. I've had the car 3 years. Currently upon start up there's blue smoke. The plugs were oil fouled badly after a year period with roughly 500 miles driven during that time. I know it's eating oil but not sure the amount. The shop is suggesting a rebuild and maybe it needs piston rings or valve guide replacement.
> 
> However, a friend of mine says to write down the current milage. If I can go at least 700 miles and the car eats up a quart of oil max then I'm fine. If it uses up more then he would do a rebuild. Would you agree with this plan? Thanks


sounds live valve seals. if the car does not have excessive blowby indicating bad rings i would try installing perfect circle valve seals. the stock valve seals never were any good.


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## geeteeohguy (Feb 2, 2008)

All very good advice. My gut tells me it's valve seals, too. For some reason, I've run into this issue a lot on Ponchos that aren't driven a whole lot. Good thing is, you can put a set of seals in without taking the heads off. Compressed air in the cylinder on TDC and a valve spring compressor tool. An afternoon's job. If it's valve guides, then more work is needed.


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## daveh70 (Sep 4, 2008)

I'll look into it with these suggestions. Does oil fouled spark plugs MORE likely indicate bad valve seals or are bad piston rings just as likely?


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## ALKYGTO (Mar 29, 2010)

geeteeohguy said:


> All very good advice. My gut tells me it's valve seals, too. For some reason, I've run into this issue a lot on Ponchos that aren't driven a whole lot. Good thing is, you can put a set of seals in without taking the heads off. Compressed air in the cylinder on TDC and a valve spring compressor tool. An afternoon's job. If it's valve guides, then more work is needed.


:agree I'd go with this approach first and play it from there. Cheap and easy first. :cheers

The compression and leakdown testing will give you an indicator of overall engine health.


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## geeteeohguy (Feb 2, 2008)

Any oil entering the cylinders will leave oil on the plugs, whether it's past the rings or valve guides/seals. Go with the "easy" first and look into the valve seals. Very unlikely it's a ring issue with the low mileage on the engine, but always a possibility. If your compression test is ok, and the leakdown test is ok, it's the valve seals/guides.


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## dimitri (Feb 13, 2009)

:agree


geeteeohguy said:


> Any oil entering the cylinders will leave oil on the plugs, whether it's past the rings or valve guides/seals. Go with the "easy" first and look into the valve seals. Very unlikely it's a ring issue with the low mileage on the engine, but always a possibility. If your compression test is ok, and the leakdown test is ok, it's the valve seals/guides.


:agree:agree:agree:agree:agree:agree:agree:agree

If it is the valve seals, do not use teflon material seals they are terrible!!!


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## blackplate65 (May 10, 2011)

imo i think i would do the comp test just to see where ur at first u never know what people mean when they say rebuilt lol


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## jetstang (Nov 5, 2008)

To answer your question. The symptom of smoke at start up indicates valve seals, not rings. Rings smoke when it's running and have low compression.


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## daveh70 (Sep 4, 2008)

Well the shop did a cylinder leak down/compression test and some of the cylinders are pretty bad. There's 66% leakage on one. 53% on another. 35%, etc. So it's been recommended that I get an full rebuild on the block and heads. If I do this, I'm thinking of a mainly stock rebuild but to modify the motor for regular unleaded gas. Just wondering if there's any suggestions/opinions if I go in this direction. Thanks in advance for any tips. Dave.


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## freethinker (Nov 14, 2009)

daveh70 said:


> Well the shop did a cylinder leak down/compression test and some of the cylinders are pretty bad. There's 66% leakage on one. 53% on another. 35%, etc. So it's been recommended that I get an full rebuild on the block and heads. If I do this, I'm thinking of a mainly stock rebuild but to modify the motor for regular unleaded gas. Just wondering if there's any suggestions/opinions if I go in this direction. Thanks in advance for any tips. Dave.


if you want to keep the heads you have for number matching purposes you are limited to going the dished piston route.


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## geeteeohguy (Feb 2, 2008)

X2. You'll need custom pistons (Ross makes them) that are dished so that you end up with about 9:1 compression. Also, you'll need a compatible cam that is designed for 9:1 compression, like a Comp Cams XE262H or thereabouts. Upgrading to forged rods (Eagles are about $250 a set) is an excellent idea as well. This combo will run on 89 octane, and run very strong. Any leakdown above about 15% is not a good thing, IMO. 66% is indicative of a broken ring. Good luck with the project!!


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## jetstang (Nov 5, 2008)

Time for a rebuild for sure, good luck.


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## daveh70 (Sep 4, 2008)

Getting it done. Also getting a freshly rebuilt correct transmission M20 4 speed (because mine is a 69 Chevy trans) and a correct 64 Hurst shifter restored with correct linkage. Look and you can see the original paint on motor below the "incorrect" blue above it. We're doing a mainly stock rebuild. This is the correct numbers matching motor.


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