LSVTEC 91 Civic

Curious, my car burns oil (I can see the blue smoke/smell the burnt oil) ONLY when I de-accelerate after a high RPM 3rd/4th gear pull. What usually causes this? It doesn't smoke @ WOT, only when I let off the pedal.

PCV valve is new, cylinder compression is 270psi in all 4.

Any suggestions?

uNF$@#!

sounds like your oil rings are bad...which would let the oil into the combustion chambers when decelerating...or engine breaking..i.e. negative pressure.

PURPLETERROR aka BIGMATT

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 255.255.255.255 &raquo;</TD></TR><TR><TD CLASS="quote">sounds like your oil rings are bad...which would let the oil into the combustion chambers when decelerating...or engine breaking..i.e. negative pressure.</TD></TR></TABLE>

I agree

Takumi Fujiwara

mototuneusa speaks of the importance of "engine breaking" during break in... could these symptoms be from improper break-in?

LSVTEC 91 Civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Takumi Fujiwara &raquo;</TD></TR><TR><TD CLASS="quote">mototuneusa speaks of the importance of "engine breaking" during break in... could these symptoms be from improper break-in?</TD></TR></TABLE>

Nah, it was broke in properly... Ran nice and hard.

Compression is 270 even in all cylinders, any sure way to test for bad oil control rings?

EE_Chris

If you let off the throttle after a high speed run, there is a lot of vacuum in the manifold. Maybe there is enough vacuum, coupled with near-shot valve guide seals, that its pulling oil past them.

mmuller

i was just going to say the same. valve seals

uNF$@#!

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LSVTEC 91 Civic &raquo;</TD></TR><TR><TD CLASS="quote">

Nah, it was broke in properly... Ran nice and hard.

Compression is 270 even in all cylinders, any sure way to test for bad oil control rings?</TD></TR></TABLE>

oil rings arent the same as compression (piston) rings.

do a leakdown test to find out the % in each cylinder. This will tell you if you need to fix the problem.

i've seen leakdowns on a 100k stock motor... should be around ~1%, to give you an idea.

EE_Chris

A leakdown test will tell you the condition of the OIL RINGS?

LSVTEC 91 Civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">i was just going to say the same. valve seals</TD></TR></TABLE>

Valve seals have about 3k miles on them <TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 255.255.255.255 &raquo;</TD></TR><TR><TD CLASS="quote">oil rings arent the same as compression (piston) rings.

do a leakdown test to find out the % in each cylinder. This will tell you if you need to fix the problem.

i've seen leakdowns on a 100k stock motor... should be around ~1%, to give you an idea.</TD></TR></TABLE>

So, a leakdown test will tell me if oil control rings are shot?

Some BITOG members also brought to my attention... that this could be normal.
They said oil could be pulled past the rings with a lot of Vacuum and oil pressure, I do get 100+ oil pressure at WOT..

Would an oil catch can setup help me out with this problem?


Modified by LSVTEC 91 Civic at 5:53 PM 5/23/2005

LSVTEC 91 Civic

Bump for another idea.

I have a hose running from my valve cover to my intake... should I remove this and replace it with a valve cover breather?

Runnerdown

Sorry dude, bad ring seal. You can try all the tricks you want but thats what it comes down to.

LSVTEC 91 Civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Runnerdown &raquo;</TD></TR><TR><TD CLASS="quote">Sorry dude, bad ring seal. You can try all the tricks you want but thats what it comes down to.</TD></TR></TABLE>

I'll do a leakdown test this weekend.

Runnerdown

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LSVTEC 91 Civic &raquo;</TD></TR><TR><TD CLASS="quote">

I'll do a leakdown test this weekend.</TD></TR></TABLE>


Its likely this will reveal nothing. how can that test mimmick the conditions of which you are experiencing oil burning? Something to think about...

I went through the same exact situation before, just so you know im not posting here to make random guesses

LSVTEC 91 Civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Runnerdown &raquo;</TD></TR><TR><TD CLASS="quote">Its likely this will reveal nothing. how can that test mimmick the conditions of which you are experiencing oil burning? Something to think about...

I went through the same exact situation before, just so you know im not posting here to make random guesses</TD></TR></TABLE>

Okay.. I'll just go ahead and band-aid it with an oil catch can and a fill of M1 0w-40. This motor will last.

I just need to do something about the crankcase pressure, I've already had to replace cam seals, now the rear main seal is bad... it took a pretty big ****. I leave an oil mess everywhere I park, what a mess.

StorminMatt

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LSVTEC 91 Civic &raquo;</TD></TR><TR><TD CLASS="quote">

Okay.. I'll just go ahead and band-aid it with an oil catch can and a fill of M1 0w-40. This motor will last.

I just need to do something about the crankcase pressure, I've already had to replace cam seals, now the rear main seal is bad... it took a pretty big ****. I leave an oil mess everywhere I park, what a mess. </TD></TR></TABLE>

There is a possibility that you could have problems with your PCV system. Especially if you are blowing seals left and right. Also consider that if you are blowing these seals, you could also have blown one or more of the valve stem seals. I personally think one or more bad valve stem seals is a better possibility than rings. The mere fact that this only happens on deceleration (when intake manifold vacuum is at its very highest) points directly to the valve stem seals.

LSVTEC 91 Civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StorminMatt &raquo;</TD></TR><TR><TD CLASS="quote">There is a possibility that you could have problems with your PCV system. Especially if you are blowing seals left and right. Also consider that if you are blowing these seals, you could also have blown one or more of the valve stem seals. I personally think one or more bad valve stem seals is a better possibility than rings. The mere fact that this only happens on deceleration (when intake manifold vacuum is at its very highest) points directly to the valve stem seals.</TD></TR></TABLE>

I was thinking the PCV system isn't working good enough as well, but my cylinder head only has about 3k miles on it (new valve seals), and my plugs look great...

What's the best way to eliminate crankcase pressure?

StorminMatt

You could try replacing your PCV valve. But keep in mind that if you have excessive crankcase pressure, then you likely have a ring sealing problem. But even this is odd, as a ring sealing problem is going to generate the most blowby at high-throttle conditions.