I tried to do a quick search and found nothing but i'm sure there's information out there. I was driving kind of hard today and looked in my side mirror and notice that when i shift at high rpm, above 5500rpm there's a poof of smoke behind me. Doesn't seem to smoke any other times and the car pulls nicely, is it getting time for a new motor? rings worn? Can't exactly say what color the smoke is maybe bluish, definitly not white though. Is there anything i can do? Decarbonizer or is it beyond that?

 

BLUISH SMOKE IS OIL IN THE SMOKE. AND IT ONLY DOES IT WHEN YOU SHIFT IN VTEC IM ASSUMING

 

i have this too. how bad is it?

 

A compresion test will tell you how bad it is or isnt, IF it is.

You could have something as simple as needing a new valve cover gasket. If your seals to the spark plugs are leaking in oil at higher pressure, that can cause blueish smoke.

 

Ive seen this in just about all vtec engines especialy in engines over 100,000 miles most of the time its just a little oil getting past the rings at high rpm. My old prelude had like 180,xxx miles on it and it didnt even have a 10% loss in compression. Just keep an eye on your oil level and make sure your not lossing more than a quart between oil changes.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Acidcrakker &raquo;</TD></TR><TR><TD CLASS="quote">A compresion test will tell you how bad it is or isnt,

. </TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Acidcrakker &raquo;</TD></TR><TR><TD CLASS="quote">A compresion test will tell you how bad it is or isnt, IF it is.

You could have something as simple as needing a new valve cover gasket. If your seals to the spark plugs are leaking in oil at higher pressure, that can cause blueish smoke. </TD></TR></TABLE>

*shakes head firmly*

Acid, verify your **** bud.

Leaking oil out of places like that will be a constant, and will not appear as smoke mixed in with the exhaust, it will either appear as drips down from where the leak is, or at most, dripping onto the exhaust pipe and generating smoke right there when/where it burns.

Leaky spark plug hole gaskets will ruin plugs/wires and their contact, and cause misfires, due to a drippy leak of oil. Direct oil pressure is NOT applied to the spark plug hole gaskets. The spark plug hole is sealed by the compression washer on the spark plug, so unless those are bad, leaking oil into that hole will have no part in the combustion cycle.

OP: This is a problem with your piston rings, the blue smoke comes from the fact that at high rpm your cylinder walls are covered in a ton of oil (relative to lower rpm) due to the increased oil pressure at high rpm.

Your pistons' oil rings are not doing an adequate job of "wiping" the oil back down, and instead, they're letting the excess oil remain, and get burned.

The reason you see it more when you let off to shift is that the injectors cut back seriously when you let off, and there is not as much fuel in there to burn with it, or possibly burn first, so the oil is burned, and there is your smoke. Fuel burns easier than oil, which is part of why the oil "hangs around" until you let off.

 

true. i burn oil like that and my compression test reads fine...210, 210, 215, 220

 

Note there is a distinction between compression rings and oil rings, bad oil rings won't necessarily be indicated by bad compression numbers.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mgags7 &raquo;</TD></TR><TR><TD CLASS="quote">

*shakes head firmly*

Acid, verify your **** bud.

Leaking oil out of places like that will be a constant, and will not appear as smoke mixed in with the exhaust, it will either appear as drips down from where the leak is, or at most, dripping onto the exhaust pipe and generating smoke right there when/where it burns.

Leaky spark plug hole gaskets will ruin plugs/wires and their contact, and cause misfires, due to a drippy leak of oil. Direct oil pressure is NOT applied to the spark plug hole gaskets. The spark plug hole is sealed by the compression washer on the spark plug, so unless those are bad, leaking oil into that hole will have no part in the combustion cycle.

OP: This is a problem with your piston rings, the blue smoke comes from the fact that at high rpm your cylinder walls are covered in a ton of oil (relative to lower rpm) due to the increased oil pressure at high rpm.

Your pistons' oil rings are not doing an adequate job of "wiping" the oil back down, and instead, they're letting the excess oil remain, and get burned.

The reason you see it more when you let off to shift is that the injectors cut back seriously when you let off, and there is not as much fuel in there to burn with it, or possibly burn first, so the oil is burned, and there is your smoke. Fuel burns easier than oil, which is part of why the oil "hangs around" until you let off.</TD></TR></TABLE>


well said...

 

thanks mgags7, if i'm understanding correctly if my compression test comes back ok then it wouldn't be my pistons rings? Or in the second post did you mean that bad oil rings won't be necessarily indicated by GOOD compression numbers. I have a slight leak on the valve cover gasket so i guess i could take it off and while i'm at it, change out the spark plug gaskets for good measure.

 

If the replacement of the valve cover and spark plug gaskets doesn't do the trick and the compression test comes back ok, is there anything short of tearing the engine down that can be done about it?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nico.tico &raquo;</TD></TR><TR><TD CLASS="quote"> Or in the second post did you mean that bad oil rings won't be necessarily indicated by GOOD compression numbers. I have a slight leak on the valve cover gasket so i guess i could take it off and while i'm at it, change out the spark plug gaskets for good measure. </TD></TR></TABLE>

If you have a leak on the VC, it is a good idea to fix it anyways, but that is not causing this.

Take a look at this picture:


Now, look at the groove in the piston, there are 2 thin grooves above, and then the 1 thick groove below. The upper 2 grooves are for compression rings, which are the rings that seal off pressure from the piston to the cylinder wall. These rings, however, do not do a good job of wiping oil off the cylinder wall.

That is why you have the thick groove below. A thicker ring, called the oil ring, fits into that groove. That ring does the job of wiping the oil off the cylinder walls, and because it is below the two compression rings, it will not have much of an effect on compression numbers, if any at all.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nico.tico &raquo;</TD></TR><TR><TD CLASS="quote">If the replacement of the valve cover and spark plug gaskets doesn't do the trick and the compression test comes back ok, is there anything short of tearing the engine down that can be done about it?</TD></TR></TABLE>

Actually, no. No matter the result of the compression test, in order to truly fix the problem, you'd have to tear it down.

Unless the thing is a lot more serious than you led us to believe, I wouldn't bother with it.

 

yea im not gonna bother with mine. not on a car with 126k miles

 

Hey well thanks for the information and illustration. It's really not that bad. At first i didn't really know if it was my car because I was getting on the interstate next to some other cars so later that day I was on a road by myself to see if it was in fact my car. No cloud of smoke or anything just a haze. Like I said the engine is run kind of hard sometimes but well maintained so I guess I really won't bother with it much.

 

i just wanted to add that bad oil control rings will infact RAISE compression test numbers. the oil surrounding the compression rings makes for a tighter seal.

alot of places that sell engines with compression test numbers do these "wet" compression test to give false results.