When to panic about white smoke

[purzell]

So I haven't had much success getting the truck to run, what with waiting for carb adapters, fixing vacuum leak, not having timing quite right while dealing with that stuff. Today I finally got the carb back on and while cranking, got it to run, lots of white smoke, but I didn't notice a sweet smell as some describe online. Of course, then the starter quit and I couldn't restart it anyhow.

This truck sat since 2008 before I got it. I just want to make sure that after changing out the fluids and replacing the starter and coil (next in line on Friday) I'm not going to blow up the motor, based on the white smoke being really bad news.

Is it unusual that a motor that's sat for five years will blow out some smoke before getting tuned up? Or is it likely to be one of the horrible scenarios: cracked something, valves, coolant in oil, etc...

Is it time to learn to rebuild a motor? It's the 351v6 in my '66 GMC.

[Rich 5150 69]

Are you running an automatic...?

[purzell]

Sorry, manual tranny.

[Rich 5150 69]

Run it for while and see if it clears up...

[purzell]

OK, that's what I wanted to hear. That if I run it there's not likely to be a huge bang and a big hole appears in the motor.

Out of curiosity, and because I am a complete noob, why does a manual vs. auto matter? Thanks.

[72lb4x4]

White smoke is steam meaning coolant. A few minutes of this is bad, but in winter, people always post in panic and its nothing.

Blue smoke is oil and its getting past the valve guides or rings.

Black means too much gas and you're running rich. Look at the carb.

[purzell]

It's white, for sure. But I can't keep it running long enough to see if it lets up. There's just ALOT of it so I wanted to make sure it's ok to keep trying to run it rather than really screw it up.
Thanks guys.

[markeb01]

Oil smoke is usually blue but can also appear white. The main thing is to make sure you check the oil level frequently to make sure nothing is broken and drinking the oil. The white smoke could also indicate somebody tried to prep the engine for a long nap by pouring some type of lubricant or preservative down the spark plug holes, and it needs to burn out before it clears up.

[oem4me]

Originally Posted by purzell

Out of curiosity, and because I am a complete noob, why does a manual vs. auto matter? Thanks.

White smoke in an automatic can be as simple as a little hole inside your auto trans vacuum modulator valve. One sip of tranny fluid into the combustion chamber and you have an instant batmobile quality smokescreen. that's a $20 fix. Sorry, it's not your problem.

[joedoh]

I vote its oil, likely all your carb work has filled the crankcase with gas running past the rings and is thinning the oil. had a truck do this once and changed the oil and cleaned the plugs, after a couple miles it was fine.


to see if this is the problem, the test is easy. pull the dipstock and see if it smells like gas (a LOT like gas) and if the oil is really thin. if so change the oil and run it a good while.

[72lb4x4]

Change the oil.
Turn the engine w/ a wrench.
rebuild the carb
Spray B12 or carbcleaner in the ..... carb
??

An engine that sat for years in today's time frame with the bad gas we have

[skidpan]

I just worked on a caddy(fuel injected) that was dumping a boat load of fuel into the engine due to a bad objectors, and I was getting snow white smoke out of the exhaust. I was worried about a blown head dumping coolant, cause it, but if you put your hand in the smoke it smelled as if you dumped it into a bucket of gas
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[purzell]

Joedoh, I think you called it. The oil smells like gas and is thin. I'm going to change it out and clean the plugs, thinking 20W50, and see how that looks. So far fortunately I'm not seeing any indication of coolant in the oil or smell of coolant in the exhaust.

[Big Fenders]

If I remember right if a blown head gasket is suspected you would see bubbles in your radiator coolant. Remove radiator when cool and warm up engine and look for bubbles....hopefully not.
Bob

[IdahoProcess]

I have a 73 Chevy truck that is blowing white smoke from the exhaust. My truck is automatic. I noticed it slightly a few weeks ago and a friend said it was probably just steam. Today I returned from an 80 mile trip and when exiting the Hwy the smoke caught my eye in the side mirror because it seemed more substantial. When I accelerated, the smoke became quite thick (still white) and when stopped it seems to collect slightly but nothing major.

I really don't know what to do and am fearful that I'm totally screwed - any insight would be greatly appreciated.

[Captainfab]

Have you checked your coolant level? Have you checked your oil to see if there is any water mixed in it?

Originally Posted by IdahoProcess

I have a 73 Chevy truck that is blowing white smoke from the exhaust. My truck is automatic. I noticed it slightly a few weeks ago and a friend said it was probably just steam. Today I returned from an 80 mile trip and when exiting the Hwy the smoke caught my eye in the side mirror because it seemed more substantial. When I accelerated, the smoke became quite thick (still white) and when stopped it seems to collect slightly but nothing major.

I really don't know what to do and am fearful that I'm totally screwed - any insight would be greatly appreciated.

[RANDY COX]

x2^^ what Capt.Fab said...