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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: septantrionalis on January 26, 2019, 05:57:52 PM
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Does anyone know what would cause white smoke to come out from underneath their truck? This only happened once while really pushing the truck.
A bit of history. I have a 1974 Chevy K10 with a newly installed 383 stroker engine and Holley Carb with an NP203 tcase and TH350 transmission. I live in Denver and decided to take the truck up to Dillon, CO. I pretty much hauled it going from Denver to Eisenhower tunnel. However, when I looked behind my truck while going up Eisenhower tunnel, I noticed a ton of "white" smoke coming out from underneath the truck. I don't know if it was coming out of the exhaust because my exhaust is hidden underneath the truck. Anyway, I backed off the gas and about 10 seconds later, the smoke stopped. I pretty much babied it the rest of the way to Dillon, and on the way home and never saw the smoke again.
For those who aren't familiar with I-70 in Colorado and Eisenhower Tunnel, the grade is about 6% climbing to 11,158’ after several miles.
Any ideas?
I thought maybe the transmission was slipping causing the automatic transmission fluid to heat up, but thats just a guess.
Another idea was the high altitude was causing the engine to run rich, but I'd think the smoke would be black.
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I should also mention that I didn’t see anything physically wrong with the truck afterward. I opened the hood and looked under the hood at the next stop. No leaks, nothing. The truck feels like it runs fine too.
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White smoke would be ATF or coolant. If the trans vented onto the exhaust you would get white smoke. Check your fluid levels.
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Also check your Modulator valve vacuum line.
I had a recent failure, it would smoke intermittently.
If there is any oil inside the vacuum hose at the valve, replace the valve.