1977 Pontiac Firebird PLUME OF DENSE SMOKE OUT OF RH EXHAUS

WHITESTONEPUBLISHING

MEMBER
1977 PONTIAC FIREBIRD
V8
2WD
AUTOMATIC
15,000 MILES

1977 ponticac firebird with 400 pontiac engine.
What can cause a big plume of dense smoke out the exhaust, on right side only, at high rpm (@4000+).
Some times the smoke occurs at a little lower rpm (@3000+) when letting off accelerator such as merging from entrance ramp onto highway.
The smoke quickly clears when steady pedal is maintained.

Also another problem that might or might not be releated is that
it drips oil at high rpm out of the transmission drip pan also and
the dripping seems to stop when just idling the engine.

Have tried removing PCV and oil filler cap to ensure valve covers can breathe.

Any ideas?
Thanks

2 Replies

ERNEST CLARK

MECHANIC
1,730 POSTS

First of all, I'll need to know what color your smoke is. If it's white, then it's coolant. If it's bluish/black, then it's oil or a very rich fuel mixture.

Though sometimes white smoke can be oil, because the smoke that appears white is really a light bluish/gray.

And the oil dripping out of your transmission isn't oil, it's transmission fluid. And the reason it drips only at high r.P.M.S is because the pump pressure is high at that time and is high enough to overcome the bad gasket.

If this continues to get worse, it'll ruin your tranny.

And removing your PCV and valve cover breather will only cause pressure to build up in your crank case, which will reduce the life of your oil and may cause slight performance losses.

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Sunday, March 7th, 2010 AT 7:33 PM

WHITESTONEPUBLISHING

MEMBER
2 POSTS

Dense blue/black which starts quickly and then stops quickly as well.
It looks almost like like a sky writer airplane turning on and off the writing smoke.

It is definitely fresh engine oil, a light clear brown/yelow and not as thin as trans fluid

I also found a little of the engine oil is on the subframe rail but not a large amount.

I only removed the PCV as there are no breathers at all on these valve covers.
I removed the oil filler on the opposite side but that side has never exhibited the heavy smoke out the exhaust

UPDATE:
I removed the valve cover(RH) and used foil tape to form a temporary valve cover withOUT a tight sealed top on it.

That seems to have fixed the problem
(except it caused a little steady blue smoke due to letting a little of the oil splash on headers)

Next I will try to find a valve cover that has baffled breathers built into it.

Thanks for your response.
I appreciate the time you spent.

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Sunday, March 7th, 2010 AT 8:05 PM