yyz1970

My '72 SB with 96,000 miles always puffed a little blue smoke at startup so this winter I thought I would tackle the problem

Compression test - good results (for 96K)
replaced original valve seals with umbrella type seals

So I've driven it about 200 miles this spring and now the left side smokes blue CONSTANTLY ( worse than before) and the right side doesn't at all!

Any comments would be a great help for me:

Should I have used both Umbrella/O ring Seals?

mr303

I had the same issue with my 1974 115,00 miles, replaced seals with standard O ring type and problem was solved. I actually wanted to use umbrella seals but was unsure which ones I needed to order, so just went with the O rings.

yyz1970

ttt

FireballXL5

I've got a fresh 383 built stroker... <2500 miles or so on it so far... And will get the occasional blue puff on startup as well.. Interested to see what responses you get here, and as I diagnose my own solution I'll try to update as I find out info... Figure I'll go talk to the local corvette/engine experts and get some feedback as well...

yyz1970

Thanks for the input
I did another dry/wet compression test with good results
after running it today I did find a puddle of Oil on the intake manifold under the throttle linkage
I'm going to pull the intake and try a new gasket


Has anyone experienced a leaking intake causing Blue smoke?

forman

Yes it could happen,, you could spray starting fluid where the suspect area is and see if the rpms change ,,

yyz1970

thanks forman i'll give that a try

bozzman3

I had a internal intake leak that caused the car to burn oil on the left side of the engine.The gasket split at the intake and sucked oil up from the lifter valley.To check for a internal intake leak disconnect and seal the pcv grommet hole with tape.Now place a piece of plastic wrap over the other valve cover hole breather hole and rev the engine up.If the plastic wrap sucks in you have a internal vacuum leak


If you have oil leaking from the intake I would replace the gasket anyway

birdsmith

What he said. It's your left side intake gasket, it's pulling oil into the cylinders from the head-to-intake joint. As long as no ill-conceived machine work was done to your engine recently it shouldn't be too terribly difficult to correct with a good set of new, properly-installed gaskets.

yyz1970

thanks for the help

I know what I'm doing Saturday

doorgunner

The umbrella seals were very brittle and I also had an oil puddle at the intake on the driver's side......new valve stem umbrellas seals and intake gaskets cured the smoking (and oil consumption/1 qt. at 3,000 miles).

Patro46

Yup. More than once. If you have an intake runner to cylinder head gasket leak on the lower side of the intake runner, it will indeed draw oil into that runner. If this happens, that cylinder in question will undoubtedly be burning oil, easily proven via spark plug inspection.

A rule of thumb taught to me by an old timer goes like this:
If it smokes under constant acceleration, it's the rings. If you wind the engine up driving down the road and let off the gas in gear, then let it wind down on it's own, then hit the gas pedal again. If it smokes then, it's valve seals/valve guides, ect. Under deceleration, bad valve seals of guides will "draw" oil into the cylinder and smoke when you hit the gas.

yyz1970

are FELPRO a good gasket to buy?
The NAPA guy has 4 different types

bozzman3

buy the felpro performance gasket set 1205 or 1206

gcusmano74

Use a soft gasket set for an aluminum manifold. I think Felpro calls it "Print-o-seal".