chasing corvettes

Hi everyone, i posted a thread about white smoke before, ended up bringing the car to a mechanic and he cleared it of any head gasket problems. And said it was fine, compression and all. But now the smoke is constant even after driving for 20 + minutes at 190 degrees, and im in sd so its been 70-75 degrees all week.
On top of the constant smoke the oil pressure has began to drop, ive read that its normal for the pressure to change at idle but mine used to always sit between 45 psi and 55 psi. Now in nuetral or when the clutch is down the oil pressure drops to 20 psi, although with a small amount of gas it shoots back up to 45.
As im writing this im thinking i might just need to up the idle speed a tiny bit to fix the pressure going down, because when i first put it in nuetral the engine sounds like its close to dying.

Sorry for the long post, what do you guys think?

LB66383

20 psi at idle isn't bad, more than adequate. However......if you're getting white smoke out of the exhaust, then it sounds like you're getting coolant in the combustion chamber(s), which isn't good. If it is also getting into the oil and diluting it, that's bad. Have you pulled the dipstick to look at the oil -- the consistency and color?

Mark Riles

White smoke is bad because it involves a possible breach in your coolant system and possible introduction of coolant into your engine oil system. Check your coolant level and check your engine oil for a milky appearance that is indicative of a mixture of coolant and oil. I would be interested to know what tests the mechanic ran to tell you it was okay. It is clear you have an issue. If you do indeed have coolant in your oil then you have some work ahead of you to find the culprit.

wcsinx

What does the exhaust smell like? Does it have a kind of sickly-sweet smell to it? And is it steam or smoke that you're seeing?

I would concur that you most likely have blown a headgasket. Your oil pressure is dropping because the coolant is thinning it out.

chasing corvettes

Thanks for all the responses,
The exhaust really doesnt smell like anything just exhaust gas, i compared it to a 71 duster i have, they smell about the same, the vette's a bit richer smelling. The oil is also a nice solid color, not diluted looking, and the coolent level hasn't dropped.

It seems more like steam, its the same color and desity as when the car is starting cold, it just never seems to stop. Again thats after the engine is at 190 for 20 minutes.

I looked up some you tube videos of cars with a blown head gasket, my car is not giving off that much smoke, its a much thinner more steam like smoke, like if the car were cold. Is it possible for a car to just naturally blow smoke through the side pipes?

And the cars not down on power at all.

ezobens

Do you have an automatic or stick?

If you have an automatic, the vacuum modulator may have a leak (bad diaphragm) and it will suck trans fluid into the motor via the vacuum line and you'll get pretty white smoke...

As kids, we used to squirt AFT down the carb just to annoy the neighbors.. Mosquito abatement!

chasing corvettes

HAHA that sounds really fun. (Needless to say, in 18)
Unfortunetly its a manual.

Anyway to post a video on this website, I'd like to show you guys what it looks like.

scottyp99

You have side pipes. Probably no h-pipe connecting both exhausts, right? Do both exhausts produce this white smoke evenly, or does one side smoke more than the other? An earlier post asked you what tests the mechanic did to eliminate the head gasket as a cause, can you answer that? It would really help.

White smoke usually means coolant. Oil burns blue, and too much gas will make black smoke.It should have a very distinctive odor, kind of like pancake syrup,....sort of. If it's not a head gasket, the only other things I can think of would be a crack in the block or head, or maybe the intake manifold gasket is letting coolant reach the intake port. (this one is really reaching, I can't see an intake gasket leaking coolant into intake port and not into lifter valley, too.) Well, anyway, good luck,


Scott

chasing corvettes

The side pipes are not connected together. I did notice that the smoke seemed like it was coming from one side at a time, thought it was just my imagination. Man this isn't looking great.
I guess its back to the mechanic and ill report exactly what he says.
Not that i plan on doing it, but, how long could a car run with a cracked head gasket? And then what would happen? Does the coolant get into the combustion chamber and the oil diluting everything till something else breaks?

Thanks for all the responses

chasing corvettes

And no i can't remeber what the mechanic said, i heard it wasn't a head gasket and was very excited, so i stopped listening

scottyp99

As far as how long an engine can run with a blown head gasket, that depends on a buncha different things. If you are leaking coolant into a combustion chamber, and it's not enough to make it lock up (hydrostatic lock) it could run for a long time. Still bad for the engine in the long run, tho. If the coolant is getting into the oil, well then, not long at all, for obvious reasons.

Does the white smoke clear up after awhile? It could just be something as simple as condensation that builds up inside the pipes as they cool off. It would burn off pretty quickly, tho, a matter of a few minutes.

Does it really switch back and forth between sides? And only one side at a time? That is really weird, I don't know what to make of that.


Scott

scottw

If the head gaket is good, you may be looking at an intake gasket that is leaking. If so, very cheap and easy to fix. Take out distributor, a few bolts, clean everything very good, replace gasket and you're done.

jackson

I'd be looking at replacing both right & left intake gaskets ... I have seen them leak into ports while not leaking into lifter valley.

If you've been considering replacing cam and/or timing set ... now's the time to consider including that with intake gasket job.

chasing corvettes

I took the car to my mechanic, it turned out to be a leaking seal letting oil into one of the cylinders. Explains the other post i made about the popping sound, the oil keeps fauling up the spark plug.
Thanks for all your help.

mrmagrath

Coincidence! I just did mine for the same reason last weekend. Manifold gasket. Oil getting into the cylinders and fouling the plugs, plus leaning out the mixture and backfiring through the carb.