FYI on motors that smoke

[TrailBeast]

I see frequently someone mention that a motor smokes on startup, and everyone jumps right to bad rings or valve stem seals.
Neither may actually be the case and I will tell you why.

For one, a cylinder/s that misfire suck oil up through the rings and dump that oil right into an exhaust system that is hot from the cylinders that are running.
Sometimes smoking can be cured by making sure all cylinders are firing.

Another possibility is an intake gasket leak, that allows oil to get into the intake ports.

Also, valve cover leaks can soak between the heads and exhaust manifolds after shutdown, and burn off inside the exhaust when the engine is started again.

So let me say this one more time.
Smoking on startup is NOT always caused by rings or stem seals.

I just read three pages of “my motor smokes on startup and runs like crap”
But not one mention of the possibility that it smokes BECAUSE it runs like crap.

Ok, rant over.

 

[Demonracer]

My take on smoking engines is, if they sit for a period of time they are going to smoke upon startup. Even though the tolerances on my race motor is dead on factory specs, it smokes upon initial startup. That is the nature of internal combustion engines, especially if the specs are a bit larger than normal. It is not a bad thing unless you look like a fogging machine running down the road.

 

[Oldmanmopar]

If your engine is smoking in the morning on start up its time to take it to rehab.

If its smoking oil first thing in the morning its probably addicted. Take it for help. Smoking oils should only occur after working hard and this should be in the evening after a couple beers or a meal.

I am sorry to hear your having problems with a family member. This could have been caused by abuse after it was first purchased

My uncle abused his son and his car They both started smoking at a very low mileage and young age. His son although very attractive still has smoking issues today.

 

[lemondana]

I have a smoking story. My best friend, when he turned 16, inherited his older brother's 66 SS396 Chevelle. It smoked so bad that he started running straight STP in it. It would blow flames out the exhaust when he backed it down. Then he let a classmate drive it. He drove it under a semi trailer, making it a convertable. He didn't have to add anymore STP.

 

[Hysteric]

For one, a cylinder/s that misfire suck oil up through the rings and dump that oil right into an exhaust system that is hot from the cylinders that are running.
Sometimes smoking can be cured by making sure all cylinders are firing.

This^^^ And it shows up on the plugs. If the cylinder doesn't fire correctly it doesn't push out the rings to seal the bore.

 

[clementine]

Was talking with a friend yesterday about a 80s corvette he just bought. 350 smoked a fair amount running down the road. Said something about putting ATF in the cylinders and letting it sit. Said something about sucking the oil out after bouncing the front end around and after it cleared out there was no more smoking....

Maybe one of you old timers can confirm or deny?

 

[TrailBeast]

Was talking with a friend yesterday about a 80s corvette he just bought. 350 smoked a fair amount running down the road. Said something about putting ATF in the cylinders and letting it sit. Said something about sucking the oil out after bouncing the front end around and after it cleared out there was no more smoking....

Maybe one of you old timers can confirm or deny?

ATF is high in detergents and can free up rings that are sticking from carbon buildup.

 

[FISHYPETE]

Back around 1976 my cousin had a 66 Chevell 396 with a horrible light metallic green paint job. It smoked a lot of blue but it was a really fast car. He passed last Sun, may he Rest In Peace

 

[RustyRatRod]

Lost of reasons one can smoke and one that there's really "nothing" wrong with is PCV/crankcase vent trouble. That can make one smoke right quick and there's nothing "wrong" with the internals of the engine.

 

[RustyRatRod]

Back around 1976 my cousin had a 66 Chevell 396 with a horrible light metallic green paint job. It smoked a lot of blue but it was a really fast car. He passed last Sun, may he Rest In Peace

My condolences.

 

[Uncle Bob]

Interesting, I've got a camper van with a smokey 360, supposedly only 80k miles on it. I replaced the valves seals last year, no improvement but I'm not sure I ran it long enough to be sure (dry rotted tires). When I parked it the smoke was so bad that after a while the engine would try to die at idle. I kind of questioned the intake manifold but if you've ever worked on a mid-70s van you know that's not a picnic. No joke it was easier to replace the valve seals than it would be to change the intake gasket.

It's a shame because it's got a fiberglass camper body on it, and little rust none of it in significant places. If it was trustworthy we would've doubled the mileage on it by now.

 

[Ricks70Duster340]

Interesting, I've got a camper van with a smokey 360, supposedly only 80k miles on it. I replaced the valves seals last year, no improvement but I'm not sure I ran it long enough to be sure (dry rotted tires). When I parked it the smoke was so bad that after a while the engine would try to die at idle. I kind of questioned the intake manifold but if you've ever worked on a mid-70s van you know that's not a picnic. No joke it was easier to replace the valve seals than it would be to change the intake gasket.

It's a shame because it's got a fiberglass camper body on it, and little rust none of it in significant places. If it was trustworthy we would've doubled the mileage on it by now.

The one thing I did like about those vans is once the dog house is off, it is a lot easier to get to the BACK of the engine and the carb! The front, not!

 

[AJ/FormS]

In late summer of 1970, I bought a 1970 Swinger 340 with less than 11,000 miles on it. It didn't smoke all that much but it regularly used a quart in 900 miles. It was still on the 5n50 warranty, so I took it to the Dealer.
The story I got from the service department was, that this was normal.
So I went back to driving the snot out of it.
A year or so later, I blew that engine up, and I got a new one under warranty. It didn't smoke so much, but it also didn't make nearly the same power.

My conclusion was, that 340s need to smoke to make power, lol.