Smoke coming out of air intake?

[Samuelpenner]

I have smoke lightly coming out of the snout of my air intake immediately after I shut off the truck... any idea what this could be?

The truck is a '76 C10 with 250 Inline 6.

Other notes:

I have a good amount of white smoke coming out of the tailpipe while I drive. (even more when Idling while moving). I recently replaced the head gasket and now think that maybe the issue is the rings. It is obviously smoke that is burning because I am constantly having to refill it and the radiator overflow is still full.

I have noticed that since this issue has started that when shutting off the truck it will seem to attempt to start again right away and then die off again.

I have smelt the smoke but cant really tell what it is.. maybe gas or antifreeze?

Any help is appreciated! Thanks!

[74 C-10 Shorty]

Sounds like water?, if it was rings it would be oil and that's blue.

[zieg85]

White smoke from the tail pipe usually is water mixing with the exhaust gas, head gasket issue or cracked head.  Smoke coming from the air cleaner is usually blue, blow by caused by worn rings.  May be time for a rebuild.  My $.02... High idle or to far advanced timing would cause the engine to not want to shut off or dieseling.  What is your oil consumption?  I had a 350 in my 82 C10 that ran great, smoked some but not drastic, puffed out of the air cleaner because of worn rings.  It passed the emission test just fine but burned a quart of oil every 750 miles...

[rich weyand]

Antifreeze leak at the head gasket.  Worse at idle because the intake vacuum is higher.  When you replaced the head gasket, you did something wrong....

[bd]

Or, as Zieg stated, you have a crack in the iron.  What prompted you to replace the head gasket initially?

Edit:
Standard transmission?

[74 C-10 Shorty]

Head bolts not sealed maybe???...

Just noticed it was an IL6, hope he didn't torque that front bolt too tight, that is a weak spot very little material there and it's easy to crack the block.

[Samuelpenner]

Sounds like water?, if it was rings it would be oil and that's blue.

I am pretty positive it is oil. As I said before, my antifreeze is never needing to be refilled. On the other hand my oil is needing to be refilled (about a quart) probably once a week after driving no more than 300 miles..

Isnt burning oil usually white with a hint of blue? In the sun while driving I can see possibly a light hint of blue but its a bit hard to tell

[Samuelpenner]

White smoke from the tail pipe usually is water mixing with the exhaust gas, head gasket issue or cracked head.  Smoke coming from the air cleaner is usually blue, blow by caused by worn rings.  May be time for a rebuild.  My $.02... High idle or to far advanced timing would cause the engine to not want to shut off or dieseling.  What is your oil consumption?  I had a 350 in my 82 C10 that ran great, smoked some but not drastic, puffed out of the air cleaner because of worn rings.  It passed the emission test just fine but burned a quart of oil every 750 miles...

I think the smoke looks more gray? it might be blue though, I havent held a light up to it to check yet.. I talked to a guy at my local shop and he was thinking rings sounded right as well recommended that I rebuild it.

I have set the timing within the month at 4Before as it recommends. Its possible that the idle is off however because I do not have a tachometer to use to get it right. I have been doing it to my best ability by "ear" I guess you can say.. I was thinking maybe it was starved too much? is that possible? Or is it possible that this mystery smoke in the air intake is causing it to "diesel" by possibly having unburnt fuel in it and causing it to do so?

[Samuelpenner]

Antifreeze leak at the head gasket.  Worse at idle because the intake vacuum is higher.  When you replaced the head gasket, you did something wrong....

This was my first attempt at changing the head gasket so this is a major possibility but again I have to stress that I am not needing to refill my antifreeze. Its levels have stayed consistently normal. My oil on the other hand is having to be refilled weekly and I have only found a small barely dripping leak that doesnt even leave driveway spots... With that in mind I really cant see how it is water burning :/ is it possible the same could be happening with oil?

[Samuelpenner]

Head bolts not sealed maybe???...

Just noticed it was an IL6, hope he didn't torque that front bolt too tight, that is a weak spot very little material there and it's easy to crack the block.

I followed the manual to a "t" with tightening everything but of course this could be possible... I actually did not even replace the headbolts. Is this the possible issue?

[bd]

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?

[rich weyand]

Here's some ideas: http://autos.aol.com/article/car-smoke/.

[Irish_Alley]

with the smoke coming out the intake when the engine is shut off, i would be thinking blow by and coming out the tail also blow by.  since oil is the only fluid your loosing this also points to blow by. three strikes your out

[rich weyand]

with the smoke coming out the intake when the engine is shut off, i would be thinking blow by and coming out the tail also blow by.  since oil is the only fluid your loosing this also points to blow by. three strikes your out

So it's rings or head gasket, right?

[Irish_Alley]

lol what. i would say rings since its coming out the intake. been a while since i messed with a inline 6 but if i can remember right theres a hose going from the valve cover to the intake and this is probably where the smoke is coming from once he shuts off the engine

 

I think most of us misinterpreted your first post. 

 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.