I took my 1970 Chevelle SS 396 out today and I thought I was running rather well. All of a sudden I was blowing LOTS of smoke out the rear from I believe both sides. I pulled over and saw nothing leaking and my mechanical gauges indicated oil pressure and engine temp were fine. I got the car home and the smoke seemed to minimize and then disappear at idle. I let the car sit for a bit and it leaked nothing before I put her in the garage. When she was warm but not cold I checked the fluids and all was OK. No signs of oil in the water or water in the oil. All coolant and fluid levels are spot on. Engine is NOT making any noises but did puff smoke on second start up. PCV valve is working fine and not clogged. The car has An Edlebrock Thunder Series 1806 carb. What gives? What should I be checking?? Thanks
Did you check your transmission fluid? I've had a pump seal on a truck that would leak like a sieve when hot, and I'd look like James Bond doing a smoke screen when it would happen from the fluid burning on the exhaust. Let the truck cool down, and it would act just fine again.
I want to say white smoke and the transmission fluid like all the other was fine. That's why I am stumped. Am I dumping fuel??
When it started smoking, how did it run other than the smoke? If it was pouring that much fuel to it, it should've been a bogging pig at the time, and your oil level most likely would go up from all the unburned fuel.
I had a Big Block Chevy do that once, and found out the valve stem seals were hard and started to crack. They were letting oil get past them and into the cylinders, so there was a lot of smoke during first start-up until the oil burned out. They also did like you stated, with a little smoke on later start-ups as there was only a little oil getting by until the next start-up. I replaced them and the problem went away. Duane
I did not have any smoke until after I got on it. When I saw the smoke "and it was thick" I slowed down to listen to the engine and watched my gauges, NO ISSUES! Got home, watched for leaks, looked at fluid levels, checked for cross contamination and NOTHING! Maybe the valve stem seals are an issue but it a current rebuild. How do you check?
You pull the valve covers off and visually look at them. They will be inside the valve springs. What Duane is talking about should be pretty obvious.
Mine were breaking up and looked like pieces of Masonite/hard black plastic pieces inside the springs. Duane
Just started the car up, no smoke. Backed out my driveway and hit her hard. Other than the tire smoke, nothing. Took her on the road and hit her hard getting on and off the gas, no engine noise, nothing! What the heck!!
I've had two similar situations. 1. Valve seals. white smoke / blue only on hard on hard acceleration. 2. Carb needle and seat. Got some crap in it, too much fuel, lots of thick, more black smoke. I got in it for a bit and it cleared up. Although I did do a rebuild on the carb just to be sure. On this second time it ran like a pig while happening. Would not idle at all.
Once I had put too much tranny fluid in my BB turbo 400. Took it out on the freeway one nice fall day a month later and stomped it at 55mph...blew a bunch of whiteish smoke out the back. I thought I had damaged something in the engine but it ran perfectly all the way back home. Talked to my local Buick Guru and he said I just puked tranny fluid out the tranny vent tube. No leaks when I got back home and she ran fine ever since. Fluid hit the exhaust system and that's what caused the smoke for about 5 to 10 seconds.
Yeah, my first guess would be bad modulator valve also. Pull off the rubber hose at the modulator and see if it has trans fluid in the hose.
I have seen a failing vacuum modulator cause white smoke a few times . Once many years ago the shop I was in had an early Commodore drawing brake fluid from a leaking master cylinder through the booster.
How does one check the vacuum modulator, is it an easy swap, does it need to be adjusted after install?
