HELP!!! My truck started smoking!!!

jsin713 · March 11, 2004

I just bought a 1988 chevy 1500 w/ 75K miles w/ a 4.3 and auto trans. This morning on my way to work, I noticed whitish smoke coming out of the back end while I was doing 65mph down the highway. When I accelerate there is more smoke. When I lay off it and maintain speed, it gets lighter and goes away. Also, after I got off the highway, the trans wasn't shifting like it should. I check ed the fluid, and it's VERY LOW to say the least. My questions are 1. Could the white smoke be from the trans burning up, and 2. if not, any ideas on what types of problems cause whitish smoke?

LikeaRock14 · March 11, 2004

Ummm, someone correct me if I'm wrong, but isn't white smoke caused by water in the oil? If so, then crap, you might have a cracked block.

Like I saod, not sure, but I think that's a possibility

jsin713 · March 11, 2004

I'm guessing that that's a little extreme. Maybe something else to add, is that the smoke looked white through the rear view mirror doing 65 mph. it could have been bluish and it wasn't thick. It was like a haze

SilveradoWV · March 11, 2004

Dont think the white smoke would be a tranny problem if it was coming out of the exhaust pipe. If it is coming out of the exhaust pipe, could it be steam? The '91 K1500 350 we used to have would have white steam come out for about the first 20 minutes it seemed. It could be the cracked block etc... like said above but you should notice an anitfreeze loss or an antifreeze look or smell in the oil when you drain it. If its not coming out of the exhaust pipe itself and its a good bit of smoke, you should be able to pinpoint it at idle!

jsin713 · March 11, 2004

thanks for the thoughts. I know there is an axhaust leak having something to do with a Donut?(my friend checked out a noise in the engine for me) But, Could that much smoke be coming out of that when driving comapared to it sitting and revving the engine?

seadoons · March 11, 2004

Sounds like you have a blown seal of some sort...if the smoke is blue it is burning oil. White smoke is some sort of seal - valve seal, etc. Has it lost any coolant?

Butch 02 Denali · March 11, 2004

I just bought a 1988 chevy 1500 w/ 75K miles w/ a 4.3 and auto trans. This morning on my way to work, I noticed whitish smoke coming out of the back end while I was doing 65mph down the highway. When I accelerate there is more smoke. When I lay off it and maintain speed, it gets lighter and goes away. Also, after I got off the highway, the trans wasn't shifting like it should. I check ed the fluid, and it's VERY LOW to say the least. My questions are 1. Could the white smoke be from the trans burning up, and 2. if not, any ideas on what types of problems cause whitish smoke?

It's your vacuum modulator on the tranny with a blown diaphram, sucking tranny fluid up the vacuum line. It's on the passanger side of the tranny and has a vacuum hose going into it. Less that $20 and 5 minuets work.

Butch 02 Sierra Denali

jsin713 · March 11, 2004

Thanks for the info Butch. You sound like you have a lot of confidence about that. I'll check it out, and I really hope it works. IThis is my first truck, and I'm really happy with it so far. I just don't want it to become a money pit. I am changing out the plugs/wires, distributor cap, ignition coil and module this weekend. I'll check out the vacuum modulator thingy as well

burgundyz71 · March 11, 2004

I was gonna say head gasket but butch has me convinced too.

jsin713 · March 11, 2004

I was just thinking, would the truck smoke like i mentioned earlier because of the

"vacuum modulator on the tranny with a blown diaphram, sucking tranny fluid up the vacuum line." <--WHat Butch said

Butch 02 Denali · March 11, 2004

I would almost guarantee it's the modulator. Happend to me about 5 years ago. I was in my 1990 Chevy 3500 comming off a highway to a multi lane toll booth and it started running crappy as I was slowing down. I stopped in the line of traffic and put it in neutral and reved it up a little, Looking out my passanger mirror, I see in the lane next to me this woman in a Civic with her window open that is directly in line with my exhaust pipe. The Huge cloud of smoke had filled her car and was billowing out her passanger window and I see her chocking and waving her hands. I burst out laughing, even though it wasn't funny for her. I stopped reving it and it seemed a little better. When she pulled up I apoligised to her but she was a little pi--ed! As I pulled out of the toll bootrh and the tranny was shifting early I knew right away what the problem was and put a new modulator in when I got home!

Butch 02 Sierra Denali

jsin713 · March 11, 2004

That's funny as hell! I feel sorry for her though. ANyway, I just took off to the auto store and I had a hell of a time getting there. The trans was having a hard time shifting. It was hard shifting, and i had to get it high in the rpms to get it to shift. I had to drive like 30 for a while because she wouldn't up shift and I was afraid i would damage the engine and do more damage to the trans. please tell me that the modulator causes problems like that......Pleeeaaassse!!