[Brett_ty]

Just got back from an Afghanistan deployment, 10 months my GTO sat in storage mostly. My dad started it up every other month or so and drove it around.

PROBLEM: Seems that when I get on the throttle and shift/let off, a white cloud of smoke comes billowing out the exhaust. Does not do this during idle or revving and then letting off...only while moving. I don't think it's coolant. Is this a symptom of mixture, pcv valve, timing?

Anyone know a good pontiac engine mechanic/tuner around the tacoma/Ft Lewis area?

[steve25]

White smoke most times IS coolant and it has a distinct smell, so if you place a pressure test on the rad when the motor is hot and the pressure holds, you can rule that out.
If the rad checks good than you probibly have dryed out intake valve seals that need to be replaced, unhooking and plugging the PCV is a quick and easy check to rule that out also.
Timing will have nothing to do with the issue!

[Tim Corcoran]

Sounds like it's rings or oil being pulled thru the PCV valve. If it were coolant it would do it all the time. I'd start with a compression check.

[Brett_ty]

Stationary the white smoke does not exist-only when after letting off peddling after really going through the gears. In the garage, can't smell radiator juice....more like I'm running rich if anything.

[GR8ONE68]

I have nothing to add technically on the subject, I just wanted to thank you for your service!

[WARPed]

Many year ago I had a similar problem . mine was an automatic TH400 car and it ended up being ATF, the vacuum modulator had a small leak sucking fluid in to the motor. Pulling a few plugs might help shed light on the issue.

[mrjestro]

First, thanks for your service.


A couple reputable shops not far from where you are:

http://mathewsonsautomotive.com/ These guys are in Renton. I've had good experiences with them.

Also

http://www.bloodenterprises.com/ These guys are in Auburn. I've never worked directly with them, but hear good things.

[indetrucks]

Head Gaskst?

[surfsama]

Originally Posted by Brett_ty

...only when after letting off peddling after really going through the gears. In the garage, can't smell radiator juice....more like I'm running rich if anything.

That would be when your intake vacuum is highest (decel) so if you have a pinhole leak it's likely that's when it would show. I would suggest a compression test or leak-down test (if you have a leak-down tester) and check the modulator line as WARPed suggested.

[OZZIEVILLE 67 2 door]

Originally Posted by WARPed

Many year ago I had a similar problem . mine was an automatic TH400 car and it ended up being ATF, the vacuum modulator had a small leak sucking fluid in to the motor. Pulling a few plugs might help shed light on the issue.

Had the same many years ago,,new modulator fixed the problem..

[66bonne]

From a veteran to another "Thanks for serving. Your sacrifice is appreciated."
I know I'm going to regret saying this but......the puff of white smoke means you elected a new pope.
Yep, I regret it.

Jim

[lust4speed]

And of course I thought about all the puffs of smoke and the image of new popes lined up out the door of the Vatican and down the street.

Most of us find it difficult to tell the difference between white and light blue smoke out the exhaust, so I wouldn't rule out either one at the moment. A good test would be to pull the PCV valve out of the valley pan and just leave it out of the hole and go for a test drive. If the smoke goes away, then the valve is bad (and the smoke was actually blue). Don't disconnect the PCV valve from the vacuum, just let it sit next to the grommet.

[Scarebird]

Originally Posted by lust4speed

And of course I thought about all the puffs of smoke and the image of new popes lined up out the door of the Vatican and down the street.

Most of us find it difficult to tell the difference between white and light blue smoke out the exhaust, so I wouldn't rule out either one at the moment. A good test would be to pull the PCV valve out of the valley pan and just leave it out of the hole and go for a test drive. If the smoke goes away, then the valve is bad (and the smoke was actually blue). Don't disconnect the PCV valve from the vacuum, just let it sit next to the grommet.

I was having the same issue today after letting off the gas after really stomping on it - will try this see what happens.

[steve25]

Reving a motor up even 8000 rpm out of gear and non loaded will not produce the combustion temps that take place when running down the road under load, so your lack of smoke in the garage test makes sence.
If its a rich running carb issue when letting off the throttle then the carb would be running rich also at other times and you would smell that, but that being said, if you rub your finger around in the end of the tail pipe is it a grayish dry black that gets on your finger, or is it a oily black on your finger?

[60man]

Originally Posted by WARPed

Many year ago I had a similar problem . mine was an automatic TH400 car and it ended up being ATF, the vacuum modulator had a small leak sucking fluid in to the motor. Pulling a few plugs might help shed light on the issue.

Thanks for your service !!
I would question the modulator first...only one bolt and a hose connection holds it in ..
Not very expensive as I recall...just eliminate it from possible source of smoke...

I assume your car is a automatic..
Did your Dad notice it?

[geeteeohguy]

It could be a vacuum modulator, but it would smoke at idle, too, when the vacuum is the highest. More likely it's worn intake valve guides or seals, which causes oil to be sucked into the combustion chamber only on de-cel due to high vacuum at that time. Thec the modulator first---if not that, probably worn/tired guides/seals. Not a huge issue.

[Brett_ty]

Originally Posted by steve25

Reving a motor up even 8000 rpm out of gear and non loaded will not produce the combustion temps that take place when running down the road under load, so your lack of smoke in the garage test makes sence.
If its a rich running carb issue when letting off the throttle then the carb would be running rich also at other times and you would smell that, but that being said, if you rub your finger around in the end of the tail pipe is it a grayish dry black that gets on your finger, or is it a oily black on your finger?

Steve

It is a grayish dry black- what does that mean?

[Brett_ty]

Team PY

-Thanks for the appreciation of my service. As I know many of you are Vets as well, I appreciate your service as well....Its a team effort spanding many decades! I have 17 years in and several deployments to Iraq, Afghanistan, and the Balkans...It's not easy work and thank goodness we have alot of outstanding young Americans making that selfless serving sacrifice througout this country's history.

Thanks for the advice and tips. Always appreciate this group's efforts to help one another out. Once I get some time this weekend I will go over them and see what I can deduce. Unfortantly, I dont have a compression/leak down tester and will have resource one from some place.


On my particular GTO, I dont have the brake booster any more. I had to take it off due to clearence issues with the heads (KRE). So I put on a Wildwood Disc brake Master Cylinder. Car is also a Manual (Tremec TKO) so I can rule out the ATF.

[Stuckinda60s]

Originally Posted by geeteeohguy

It could be a vacuum modulator, but it would smoke at idle, too, when the vacuum is the highest. More likely it's worn intake valve guides or seals, which causes oil to be sucked into the combustion chamber only on de-cel due to high vacuum at that time. Thec the modulator first---if not that, probably worn/tired guides/seals. Not a huge issue.

This isn't necessarily true. The vacuum is higher on decel than at idle. The modulator is a diaphragm and can seal pretty well if it's at rest. High vacuum can cause it to separate and allow ATF to be pulled through it.

The test for it is simple. Pull the hose and stick a Q-tip in the tube and wipe it around. If you get any oil on the cotton, at all, replace the modulator.

[geeteeohguy]

Good point, Rich. I agree. Also, very, very easy to check.