apie2546

Hey guys,

Had a question about blow by on my car. But to preface, its not getting fixed until the day a 350 pops in the car.

Anyway.

I have blow by on start up. Just a big puff and its over, no more burning oil. I always check oil levels (and I drive the crap out of my bird) and it never stays full, it goes a smidge down on the dipstick and stays there a long time. Just under full. Once a month maybe I'll start it up and have blow by. Which causes it to go down (dipstick is less now but still safe).

Is this still the piston ring gaps not sealing right or something else? I know the engine never stops in the same place every time. And piston rings isn't something I feel like messing with. Just want to make sure.

Could it be other factors?

aliceempire

iTrader: (14)

Sounds like the super common issue on old sbc's. The valve seals let oil in the chambers while sitting. After start up it burns that oil away and thats the end of it until it sits again.

apie2546

Yeah, I figured. Just wasn't sure if it mattered that hits a hit or miss if it leaks

aliceempire

iTrader: (14)

I had a 305 that is had to sit long enough before it would puff at me. I also had one the looked like I could fog out mosquitos. All depends on how bad your particlular seals and valve guides are.

Night rider327

iTrader: (13)

It's not blow by and it's not piston rings.

It's a very common prob. It's the valve seals and/or guides. Like others have said, it's common and will only happen every so often at 1st, then gets worse over time. It's where oil sits in the head, leaks down valve stems past the seals and into chambers. Burns off on 1st fire up and you get the puff of smoke.

If it was rings, it would smoke to some degree all the time.

If you have an on the engine valve spring compressor, air compressor, air hold socket, its a job that you can do in a couple of hours and cost you less than $10 (if the guides are within limits)

apie2546

Good news everyone!

Well I found out why this is happening.. There is a minor oil leak above the cold start injector and it leaks in there and burns it off. That's why it only happens really when cold. I plugged it off and no more burning oil. Rings are still good. Happy day

aliceempire

iTrader: (14)

Glad you found the problem but what is above the cold start injector that could leak oil? Nothing around there has oil going through it except the valve cover?

apie2546

I already did both valve covers. The valley has oil in it most of them time but my oil never runs low luckily. Its probably a minor leak somewhere. I will need to hunt around. Just happy its not internal. A happy SBC is always nice

apie2546

I fixed it! Its been below freezing here and we've had several fire calls everyday here giving me less time with my bird. Been hunting a rattle noise in my other topic and this but I found the leak. I put in a third valve cover gasket and tightened it up. 45m hwy drive and no leaks and no oil burning on start up. Hopefully this dog will run a long long time.