exhaust smoke

[QCAR17]

allright z-mechanics,

i've got smoke from my exhaust, not a lot, and it usually stops after running awhile. returns when i throttle (push peddle while sitting still) what is usually the cause of this.

thanx in advance

[mdbrandy]

White smoke? Black smoke? Blue smoke? might denote water, rich mixture, oil, respectively. More info? What year car? Any mods? Carb? Fuel Injection?......

[26th-Z]

I'll give you the quick method for white smoke.

Check your cylinder compression by standard compression guage test - remove the spark plugs and test each cylinder by turning over the engine on the starter five to ten rotations. Each cylinder should read around 160 psi or so evenly within 5% or so. If you find a low cylinder, squirt some 3-in-1 oil in the cylinder and check the compression again.

140 psi is getting pretty low for any cylinder. Suspect worn rings if the psi increases substantially. If there is no increased psi, suspect worn valve guides or valve problems.

Black smoke is from an improper fuel mixture (rich).

Steam is a blown head gasket or worse.

This info is pretty basic just to give you an idea of specific questions that will be asked sooner or later. Check it all out and let us know what you find.

[dogma420]

what is 3 in 1 oil?

Would normal motor oil do the job on the ring test?

[frank13]

Yes Motor oil can be used for a wet compression test. BUT IN VERY SMALL AMOUNTS!! One or less teaspoon or so. Any more can hydrostaticaly look up the cylinder that your are test. This can lead to bent rods/crank, broken piston ring lands. Not cool! :devious:

[frank13]

26th-Z hit the nail right on the head with the smoke describtion! :devious:

[280zx Fever]

Originally posted by frank13

Yes Motor oil can be used for a wet compression test. BUT IN VERY SMALL AMOUNTS!! One or less teaspoon or so. Any more can hydrostaticaly look up the cylinder that your are test. This can lead to bent rods/crank, broken piston ring lands. Not cool! :devious:

huh ??

Ill have to watch out when oiling my piston bores in my next engine rebuild ?