my dad keeps saying he sees smoke coming out the tail pipe but i seem to never see it i just changed plugs the other day and no oil was on them so what other reasons would smoke come out? what color? and how to test and fix? thanks
91 z28 convertible 305 tbi auto

 

That depends,

If it is only smoking on start up it's most likely the valve guides. This is really common on high mileage motors. ( Mine does like crazy 167,00 mile on a stock motor).

Other than that I would have to know the color of the smoke and what you are doing to it when it is smoking.

 

just whenever i leave or something and my car has 70,000 miles on it mabey he was justme i dont know

 

Black smoke = Rich
White = Coolant
Blue'ish = oil

 

i think its white maybe blue but there isnt oil on my spaark plugs how else woud i get oil?
and if its to rich how do i fix that?
and how would coolant get into it and how do i check
thanks so far every1

 

Thats a loaded couple of questions!

You didnt happen to get new exhaust by any chance did you? Just making sure. New exhaust will smoke sometimes.

If you're burning oil I'd say it's definitely either the valveguides or the piston rings. As Revved said, valveguides cause smoke on startup. Rings cause smoke all the time. But more when the engine is cold because the rings haven't been heated yet so they havent expanded fully.

If it's rich, look for check engine lights. Do your plugs and wires, cap and rotor...the simple ignition stuff. But FIRST, replace your O2 sensor. That fixes a LOT of rich problems.

Coolant could be from either a blown head gasket or maybe a cracked intake. If it's a headgasket...check your radiator coolant for oil floating on the top. Check your oil for water or a milky residue. Check under your oil filler cap for the same. Cracked intake, well, the engine would run like ***. Head gasket will usually cause that too, along with covering a spark plug or two in oil. But it all depends on WHERE the head gasket has broken.