oldpitpony

Hi All
I have an 05 Civic SI (1.7l SOHC VTEC) with 200,000 kms on it. It consumes a lot of oil but I don't see any blue at startup, accelerating , or decelerating.

I change the oil and a few hours of driving later, it is black with what I assume to be blowby gases. My first inclination here is to look at the rings, however a compression test on each cylinder shows above 190 on each.

Is it possible stuck oil control rings and plugged oil drainback holes could be allowing the blowby and not only causing the oil to get burnt up but also blackening it? Could valve stem or guide problems also be blackening the oil?

Ideas?

Thanks

ezone

Leftover oil in the engine that is already blackened will turn your fresh oil dark immediately.
An engine can hold up to a full quart that cannot be drained out during an oil change.

The rest is probably blowby, combustion gases.
Is the PCV good??

The usual cause is rings, no matter if you see it or not...and a compression test cannot tell you anything about the oil control rings. Knowing more about the conditions that it smokes under would lead to a better guess as to the oil burning source.
Valve stem seals tend to leak under high vacuum conditions, and worn rings tend to let more oil pass at higher RPMs. Stuck oil rings can let it smoke a lot when cold, but not always.

A cat can hide a LOT of smoke, and your rear view mirror doesn't let you see the whole scene behind you.

HTH

oldpitpony

Yes the PCV is good, I actually bought a new one just to be sure. I understand that some old black oil will remain in the engine after an oil change but I also think I have big blowby issues. I am thinking that the blackening is not likely a result of any valve seal or guide issues, my problem is cylinder wall and/or ring wear.

I also read a lot about stuck oil control rings though. Is it possible the stuck oil control rings and drain back holes being plugged is what is blackening the oil though or would the two compression rings have to be worn as well to allow the blackening I am seeing?

It is such a temptation (cheap) to try to just swap out the rings and run a honing brush down the cylinder walls to see if that fixes it.

Thanks

ezone

Send an oil sample out to get tested, you can get the real answer that way.

Short trips/cold running/lack of warmups will mimic blowby and dilution. The oil needs to get hot for a long enough time to boil out condensation and contaminants, on a regular basis.
Make sure this is not your issue before wasting a bunch of effort on this.


The drain holes in the head won't be plugged unless the head is sludged, and you have bigger problems if that is the case.

200,000km = 125,000 miles, a little early for excessive ring wear on a well cared for unit IMO, but if it has ever been hot the rings can suffer. They lose spring tension.

Stuck oil rings from carbon buildup is likely.
Clean the ring grooves thoroughly when you do it.

Switch to better quality oil too, since oil issues lead to stuck rings in many cases.


HTH

oldpitpony

Oops, I meant the oil drain back holes in the piston, where the oil control rings sit.

Thanks for the reply!

gearbox

iTrader: (95)

www.auto-rx.com works wonders. then switch to valvoline maxlife oil.

Impossible

an old trick to cleaning up your engine is to use 1 less quart of oil and run 1 quart of tranny fluit if you suspect a dirty engine...

pjb3

Not a good idea. I think the idea behind adding 1qt ATF was that since automatic transmissions tend to stay clean internally, ATF must be a good cleaner. ATF has less or no detergents because transmissions don't need it so it actually does a worse job of cleaning than motor oil.

I would agree with ezone's suggestion to get an oil analysis done so you know what is going on instead of guessing.

ac_2007

At this point, it can't hurt to Seafoam the engine and see what happenes.

My guess would be blowby gasses as well, since the engine is burning oil this is an obvious cause. The next thing would be sludge build up. Get yourself some Chevron Techron as well.

pmjr0987

I have heard marvel mystery oil works good, or at least has a chance of working in a situation like this. This post came up in a quick google search

"No one can guarantee that MMO will unstick your rings but it excels at this type of thing. If you can get it, pour a tablespoon or two into each cylinder and let it sit for a day or two. Also, replace 20% of the crankcase oil with MMO to help free the rings from the bottom side."

so pop out the spark plugs, and dump some into each cyl and let it sit and soak into the rings for 24-48 hours, dump the rest of the can into the oil. after letting it sit for the day or two put the plugs back in and start the car. i would run it semi aggressively after that and it *could* help your engine like you want it to. look into this for your self too i think its worth a shot if anything it cant hurt.