Huge smoke cloud after high speed driving?

[teambeechstreet]

I have a 90 Honda Civic w/ 4spd manual and the 1.5 engine. 260,000 miles. Using Delo 15w-40. Full tune up done about 3000 miles ago. Leaks oil but never smoked. About 300 miles ago I noticed a huge (huge as in the same size as the car) greyish/white cloud of smoke dump out of the exhaust on the highway. It only occurs when I am accelerating after slowing down from highway speeds. Ex: Driving 65 mph, hit traffic, slow down to about 25mph, shift into 2nd, floor gas pedal to pick up speed again, smoke dumps out of exhaust for about 2-3 seconds. Never happens during city driving or spirited driving through the twisties. I was told it may be valve stem seals, but wouldn't the smoke be bluish?

Thanks for any help.

 

[zyxelenator]

rings?

 

[btanchors]

I would suspect rings as well, especially with that mileage.

 

[eljefino]

I'm also going with rings, my saturn did this and new rings fixed it.

The vacuum sucks oil up on top of the pistons, and might even coat the inside of the exhaust manifold with liquid oil. Then when combustion gets hot again (you probably have fuel shut off on decelleration) the heat smolders the smoke.

You can make a huge cloud and keep running right without fouling plugs or burning too much oil in this scenario.

Now that you've gone thick with your oil, a crutch that limped me along nicely, there's not much else to do without fixing hard parts. You could try pulling the plugs and putting seafoam in for an overnight piston soak.

 

[Eddie]

It happened 300 miles ago? I suspect a pluged PCV or EGR which is allowing a larger than normal build up of crankcase pressure.

 

[SteveSRT8]

High vacuum is just as likely sucking oil past the valve stem seals as the rings.

A relatively easy fix.

 

[teambeechstreet]

Thanks for the replies. I'll try the PCV again. Thing is a pain in the butt on this motor. Rings sound about right since one of the pistons has considerably lower compression numbers than the rest.

 

[kasedian]

When in doubt, throw some MMO at it!

 

[teambeechstreet]

I actually started using MMO treatments the day I got the car back in January.

The smoke has started appearing during city driving. Smaller clouds but they are there. Hoping the new PCV helps, I'd hate to put another motor in this thing.

 

[vinu_neuro]

Originally Posted By: teambeechstreet
It only occurs when I am accelerating after slowing down from highway speeds.


Valve seals without a doubt. Try running a high-mileage for the seal conditioners. If that doesn't work you're going to have to go in there and replace them. It's one of the most tedious fixes I've ever done in my car. All that goes along with the timing belt job + much more pita.

If MMO is a solvent, that's more than likely what has caused this.

 

[Donald]

Dump the oil with MMO and add fresh oil and Auto-Rx. Its possible there is crud around the ring pack. Auto-Rx may help with that. It also "conditions" seals as opposed to causing them to swell like a high mileage oil does.

 

[teambeechstreet]

Last week I had to make a 500 mile round trip in the old honda and had about 5-6 ounces of MMO left. Decided to just empty it out into the gas tank and topped it off with some Shell 87. The car smoked a little bit on the first 100 miles but afterwards I never saw any smoke. I did about 90% highway driving over the 500 miles. Its been about a week since the trip and the smoking has disappeared completely. I really doubt the MMO in the gas tank helped at all... perhaps it was the 500 miles over a span of just two days cleared something out of the system?

 

[Scott_Tucker]

Most likely oil control rings. NOT the compression rings, although if you have low compression in one cylinder then that is an issue too. Bad oil control rings don't show up on a compression test. It is unlikely valve stem seals although with that mileage it could be both. Valve stem seals normally show up as smoke on deceleration and rings usually shows up as smoke on acceleration.