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got a good one.....I have a 2003 civic ex 1.7 170,000 miles. recently started have a lot of smoking on start up. I ran a compression check and all cyl are around 195# also ran a leak down check and it showed no abnormal leakage. decided it had to be valve guides and since there are no machine shops that I trust to do this type of work on a Honda in this area I bought and installed a reman head. Finished it up yesterday and when I started it this morning still got a lot of smoke.....I am at a loss as to what is going on.....anyone have any suggestions?

 
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Stuck oil rings.

 
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Leak down test showed less than 20% leakage in all 4 cyl. bad rings should show higher leakage. only smokes on start up, after about a mile smoke is completely gone....FIY the car has no Catalytic Converter!

 
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Still bet it's stuck oil rings.


You cannot find this with a compression test or leakdown test.
The oil rings could be completely missing and you would never discover it using those two tests.

 
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ok I agree with that, but tell me why it smokes so bad on start up then goes away after a couple of miles and you never see any smoke after that until it sits over night or for 6 or 7 hrs. I have followed this car down the road and after a couple of miles there is no smoke. none! But on start up after setting over night you can not see across the street because the smoke cloud is so bad.

 
Rep Power: 517

Wait.... you agree.... but you don't agree -- or still question?
Think about heat and how metals are affected by it.


Because the oil rings are stuck.





Carbon buildup in the ring grooves causes them to stick.
Take it apart and prove me wrong.

 
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Not arguing with you but just trying to understand. I agree with if the only rings that are stuck or bad is the oil ring, leak down might not show anything......but symptoms of bad rings is smoke on accl. and also smoke at extended idle.......this has neither. Smoke on start up after extended non running period that goes away after short period of running usually indicates valve seal and or guides......oil can't run up hill, it runs buy the valve seals and down the stems into the engine when the valve opens. BUT I just replaced the head with a rebuilt unit and I still get oil in #1 and #4 cyl after setting. same as with the original head. Seems to big a coincidence that a new head would have same problem as the old head in the same two cyl. I'm thinking some thing that affects those two cyl but not the other two and my first thought was rings and if the smoke didn't go away after a couple of miles and if I got smoke on hard accl. then I would already be tearing back in and replacing the rings and kicking myself for not doing it when I was in there the first time. My next step I think is to borrow a inspection camera pull the intake and exhaust Manifold and look at the valves and see if oil is running down the valve stems. also look at the intake and injector support and see if I can see anything there, What I don't know but I'm gonna look at everything while it is off. After that I guess rings. Unless someone comes up with some other possibility.

 
Rep Power: 517

There's more than that. Smoke on accel and high RPM is a common symptom of worn rings, but not always or necessarily stuck rings.

Smoke under high vacuum condition is typical of leaking/worn valve seals.

Neither are really hard and fast rules, there can be exceptions to every rule.

A small puff of smoke upon initial startup after sitting (through cooldown)is usually considered to be valve stem seals (and has been considered average/normal for some manufacturers and engines).

Copious amounts of mosquito-fogger smoke should not be stem seals.

It doesn't. It is splashed upward and pushed upward by moving engine parts.

The piston (and rings) shrink when cold. They expand as they warm up.
The oil rings are stuck in their grooves and allow large amounts of oil to pass upward with each piston stroke until they have been heated sufficiently to expand and seal (better) against the cylinder walls.

The top 2 rings (compression rings) aren't designed for and can't control upward migration of the oil on the cylinder walls.







My own truck: If I start it up cold and let it run for a minute, shut it off and let it sit a few minutes, then start it up again, it can fog out a block (this is actually down to 'every once in a while'). It too has stuck rings, and has been that way ever since I got it 20 years ago.

 
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ok what you say makes sense. thanks for putting up with me and helping me get a clearer picture as to what might be happening. I am stressed out over this and not thinking very clear. This is my son's car and I am trying to help him out because he doesn't have a lot of extra money to spend. I have been a mechanic for longer than I can remember but retired in 1991 after selling my shop. at 70 years old it is hard for me to do this type of work and if he had the money I would have let some one else do it. Now that I am having trouble figuring what is going on it is just bugging me that I can't fix it. I have never had a auto problem beat me and this is not going to be the first. There is a lot I don't know about all the electronics on the newer cars but this is all mechanical and I am suppose to know about this!

 
Rep Power: 517

Sorry if the first answers were too short, I jump all over many things on the net and sometimes have little time to do it.

I don't envy you LOL, I already refuse to do anything in any driveway anymore. I want a nice lift, never a creeper.

My boy got a 3 year old car for his first one, he caused many problems but stuck rings wasn't one of them LOL


Modern low tension rings plus cheaply made oil combine to cause stuck rings.


Filling cylinders with something to soak might be a possible option, but anything that gets near the bottom set of rings will likely just pass on through since they are stuck and barely touching the cylinder walls when cold. Look in Caddy Northstar forums for things like oil consumption fixes and stuck rings for ideas.

IMO the best positive fix is rering it (cleaning grooves is part of that) or get the pistons out and clean the ring grooves thoroughly, maybe reuse the rings if no wear on them.
(NO I do not hone the cylinders for new rings.)

Mopar combustion chamber cleaner is some good stuff, it eats carbon pretty good.





HTH