Smoking on acceleration

[Johnnyz453]

Recently I've noticed that some white smoke comes out from the exhaust when you gas it at a red light. Only noticed it recently. I did put marvel mystery oil in with the engine oil about a week ago to try to stop a ticking lifter. Don't know if it's from that or something else. It is also loosing oil pretty quick but not any drops on the driveway.

 

[1987 GMC Jimmy]

Recently I've noticed that some white smoke comes out from the exhaust when you gas it at a red light. Only noticed it recently. I did put marvel mystery oil in with the engine oil about a week ago to try to stop a ticking lifter. Don't know if it's from that or something else. It is also loosing oil pretty quick but not any drops on the driveway.

Sounds like you're burning oil. Not a ridiculous amount so you're just seeing it under acceleration. I'd first replace the PCV valve. I wouldn't even bother testing it; it's three dollars at O'Reilly's. Afterwards, top it off with oil, drive it, and see if the problem occurs like it did before. If not, great. If so, I think it's time for a compression test because you may have a bad ring or rings. You can borrow the compression tester from Autozone and do it yourself. If you see one or two cylinders that have an out of spec compression, there's your bad ring more than likely. I think out of spec is more than or equal to 20 pounds difference between adjacent cylinders. Someone please correct me if that's wrong. Either way, when you put all your compression numbers together there will be at least one that doesn't look like it goes with the others when dealing with bad rings. They say the motor needs to be hot when doing this. My dad used to work on the Teledyne Continental motor in his plane, and he told me a few days ago that he would always do compression tests on a hot motor because I was looking into an oil loss/blow by situation in my Caprice. If the compression test doesn't tell you anything, I would do a leak down test. Maybe your mechanic friend has a leak down tester? Oil can help seal bad rings and give you normal compression numbers so a leak down test pumps a cylinder full of compressed air and clocks how fast it leaks out. It's just good to do both to make it a thorough diagnostic, as this is an important one. If you have a ring problem, the motor will need a rebuild in the near future. Hope you can take care of it with a PCV, though. What are the miles on the engine?

 

[RangRayy]

blue smoke is usually burning oil, black fuel and white coolant. chilton book says compression values are acceptable if they are not less than 80% of maximum value, and two cylinders should be no more than 12-14 pounds different. also to do the test with an engine at operating temp.

 

[chengny]

MMO does cause white smoke at the tail pipe, but that's only when it is added to the intake air or fuel supply. It doesn't however, cause white exhaust when it is added to the lube oil system - at least in my experience. It may boil out of the lube oil and be drawn into the combustion spaces by the PCV system. But this would happen so slowly - and in such small quantities - that it wouldn't have an effect on exhaust gas color.

Unfortunately, if you continue to see white exhaust gas - especially after the engine has reached normal operating temperature - it is almost always a sign that there is coolant leakage into the combustion spaces (read - failed head gasket/cracked head).

Start monitoring your coolant level/usage.

 

[1987 GMC Jimmy]

Are you sure the smoke isn't tinged blue at all? You're loosing oil which makes me think it's an oil/engine mechanical problem, but white smoke is usually a telltale sign of a blown head gasket.

 

[rich weyand]

... but white smoke is usually a telltale sign of a blown head gasket.

Yup, or warped heads, such as from an overheat. They skinnied up the heads at one point to save weight, and went a little overboard. BTDT, got the new motor.

 

[Rusty Nail]

Meh.

I'm quicker to vote intake manifold gasket. Especially at the heat crossover, between cylinders 4 & 6.

 

[Johnnyz453]

So after adjusting valves I checked all of the different cyl. Compression and they were all at 140psi. Seemed low to me but they are all the same. Motor does have flat top pistons and a pretty heavy cam. If you put your hand behind the exhaust on the side that is smoking and have someone rev it your hand will turn black and it feels like oil or water is splattering out. Also if you put your hand behind the pipes the one that's smoking is a lot hotter And you can feel the moisture difference. Pretty sure it's a head gasket...

 

[1987 GMC Jimmy]

So after adjusting valves I checked all of the different cyl. Compression and they were all at 140psi. Seemed low to me but they are all the same. Motor does have flat top pistons and a pretty heavy cam. If you put your hand behind the exhaust on the side that is smoking and have someone rev it your hand will turn black and it feels like oil or water is splattering out. Also if you put your hand behind the pipes the one that's smoking is a lot hotter And you can feel the moisture difference. Pretty sure it's a head gasket...

Is this when it's warm? Condensation in the pipes can evaporate and aggregate and make it steam or blow out droplets when you first start it up.

 

[Rusty Nail]

Water is the by-product of that combustion process, if it was oil, it would still be there.

What kind of carburetor is installed?

 

[Georgeb]

The last time I had exhaust hotter out one pipe than the other I had my exhaust valves adjusted a little too tight. I also had an ever so slight missfire.

 

[Johnnyz453]

Water is the by-product of that combustion process, if it was oil, it would still be there.

What kind of carburetor is installed?

Has a edelbrock 600CFM manual choke 1405

 

[Johnnyz453]

The last time I had exhaust hotter out one pipe than the other I had my exhaust valves adjusted a little too tight. I also had an ever so slight missfire.

The valves were loose before adjusting them and the smoke was the same before and after adjusting the valves. Also there is no misfire

 

[Johnnyz453]

Is this when it's warm? Condensation in the pipes can evaporate and aggregate and make it steam or blow out droplets when you first start it up.

It was after awhile of running. The one side was normal but the other wasn't.only the one side had moisture.

 

[Rusty Nail]

If I were a gambling man (i'm not) , I would wager the base idle screw on that side of your 1405 has backed out and now you are running rich. It's what Edelbrock carburetors do, lose tune.
Out to richen, in to lean.
A simple solution is to turn the "water side" screw IN ( clockwise) - until it bottoms out - while making very careful to keep track of how many turns it takes. I count 1/4 turns.
Find the bottom and return it to it's original position. Duplicate that number of "quarter turns" to the "black smoke" side and I WOULD bet that tailpipe immediately begins to spit water.
That is good. If it does that, it was a simple fix.
I THINK it's about 6 quarter turns + or - .

Make sure your keep track so you can undo it if so desired.

Looking to the future, granted my knowledge of Edelbrock carburetors is very limited, BUT if you feel brave enough to contain that spring and re-install it later, you COULD remove those screws and brush WHITE OUT on the THREADS ONLY, and that will help prevent a repeat.

I respectfully defer further elaboration knowing damned good and well that other members SEEM to know more about Edelbrock carburetors than I do and maybe they will be willing to add to , or correct me.
Admittedly, I stopped using Edelbrock in the late 90's, as disclaimer.

I doubt they have changed.

Good luck!