Smoke coming out of air intake?

[rich weyand]

I rebuilt a Chevy 195 upright-six back in 1976.  Had 100,000 miles on it.  I didn't touch the main bearings, what with it being a 7-main-bearing engine.  I put in rod bearings, .020 over rings without any work on the bores, new lifters, ground and lapped the valves and put in valve oil seals.  That was a big deal because it didn't have them from the factory and it was all oil-carboned up from leaking down the valve guides.  Didn't mess with the valve guides otherwise.  I drove it for another 150,000 miles before it sucked the head gasket and I gave it last rites.

But I think you can blow-by the rings or the head gasket and get the same results.  You're pressurizing the oil system with exhaust and it will come out the breather and into the intake.  Since the head's been off recently, and it's easy to fix, I would start with the head.  New head gasket, and I would glue that sucker down with a good head gasket sealant.  Those sixes are notorious for head leaks, both the Chevy upright sixes and the Mopar slant sixes.  When I rebuilt mine, believe it or not, I sealed the head gasket on both sides with regular Perma-Gasket gasket sealer, which is not the approved method (no kidding, right?), but, like I say, I got 150,000 more miles out of it before it sucked the head gasket.

Head gasket and sealer is cheap and you can replace one in a couple hours.  Rings is another whole issue. I would change out the head gasket and seal that thing up, both sides of the gasket, as the first shot at this problem and see what you get.  And while you're at it, put umbrella valve oil seals on it.

[Irish_Alley]

if you can get smoke out both ends by a bad head gasket and if this wasnt a problem before he touched the head (dont think he ever answered why he touched them) then yeah go for it make sure all is done good. it would be a lot cheaper and easier of a fix if its just the gasket.

[Samuelpenner]

I think most of us misinterpreted your first post. 

Bluish smoke indicates oil burning; the bluer it is, the more oil you're burning.  If you think rings, run a wet/dry compression test.  You can also pull the PCV valve out of the valve cover with the engine running to see if you're puffing smoke out of the valve cover.  Crankcase pressure usually results from compression blowing past the rings, which translates to oil moving in the opposite direction past the rings into the cylinders.  Oily coke buildup on the spark plug insulators and electrodes is also a giveaway, as is having to add oil regularly when it's not dripping on the ground.

If you get an initial puff of blue smoke from the exhaust when starting cold, you may have oil leaking past the valve guides. 

You don't "need" to replace the head bolts unless they are etched from corrosion, stretched or broken.

Your thread begs the question, is the bluish smoke a "new symptom" that developed after you replaced the head gasket?

Are you running a standard or automatic transmission?

I will definitely move on to those tests. I havent had time to do them yet but thats my next step. I replaced the head gasket originally because of the white smoke and low, almost empty antifreeze. I should have checked out a few more things before putting it all back together but I am pretty new to all this.

But all that to say, I am slowly but surely narrowing down my options of what this could be. Most likely I will be saving up some more cash and having the thing rebuilt. Seems like the most logical thing to do...

[bd]

Some additional tidbits:

Spray Berryman's B-12 into the PCV valve with the engine running to clean the valve and vacuum passages.  Make sure you have unrestricted manifold vacuum to the valve.  If you're running a catalytic converter, be careful not to overheat the cat; spray B-12 for no more than 20 - 30 seconds at a time, interspersed with rest periods of 1 - 2 minutes.

I asked about the transmission, because a leaking auto trans modulator valve will pass ATF directly into the intake.  The result is grayish- to bluish-white smoke.

If you ever remove a cylinder head in the future, check the block and head sealing surfaces for flatness using a long straightedge.  Your service manual should provide the allowable tolerance.  A sealing surface warped beyond tolerance can shorten the service life of a repair.

When you decide you need to replace the valve guide seals, specify Teflon press-on seals for positive oil control over a longer service life.

Keep us apprised of what you find.