Burning Oil At Start Ups

[Mango]

I Have been getting blue smoke at start ups and getting worse!
I have been told running rich O2 sensor
Valve seals
Piston Rings
Running great shut down let it sit for a few,start up no blue smoke
199,000 miles all original
Oil Additives?
Complete engine rebuild?

 

[Ricko1966]

What are you working on? SBC BBC most likely valve seals and valve guides. O2 sensor is not a factor on a cold starts and rich causes black smoke.

 

[gmbellew]

looks like a 350 tbi suburban. I've always heard that blue smoke on start up is likely valve guide seals. but a little oil is seeping into the combustion chamber when it sits from somewhere.

 

[ChuckN]

X3 for valve seals. For the short term, you could try a thicker viscosity oil and see if it delays the inevitable for a while.

 

[squaredeal91]

Valve guide seals

 

[squaredeal91]

My 305 does it bad. I know it's valve guide seals

 

[Finkaire]

Ditto

 

[Trucksareforwork]

Planning to do valve seals over the long weekend if I can get to it.

My 305 sometimes has zero smoke and sometimes has lots of smoke at warm startup. I haven’t figured out what the correlation is.

All I can figure is that there must be some seals that are worse than others and that oil leaks in more when the engine is stopped with some valves open and not others. We will see.

 

[squaredeal91]

Mine does it more parked on flat ground. On certain angle hills it wouldn't smoke sometimes.

 

[GTX63]

Valve seals are the most likely cause. They can be changed out in an afternoon with typical hand tools and a spring compressor. There are some products on the market that will swell seals, but at 199k, it is probably time.

 

[85K304SPD]

Worn out motor. Time for a rebuild. Pull it out, have the heads rebuilt, put in new rings and bearings, gaskets of course, freeze plugs, timing chain. and then wear it out for another 50 to 100k miles, running like a new motor. Much better than working on the heads in the truck. Lots of work, and you will still have a worn out motor when you are done.

 

[Rickf]

Have you used "SEARCH" to find the answers to your questions?

 

[KnuckleBuster]

Every GM truck I've had smoked on cold start. Valve seals every time. I have 2 right now that I need to put valve seals in. GM only been in business for 100+ years. They'll build a better valve seal someday.

 

[WFO]

I'd probably just add oil when needed, until it's time for a rebuild or another engine.

 

[KnuckleBuster]

I'd probably just add oil when needed, until it's time for a rebuild or another engine.

That's certainly one way to go. Might get away with it if you put a lot of miles on it and keep the oil burned out of the exhaust. Low-mileage, city driven vehicle will damage the catalytic converter sooner.