Intermittent smoke at freeway speeds

[spidernut]

A friend is having issues with his recently fully rebuilt motor and head. Everything was fine until recently. He said that he is now getting intermittent oil smoke at around 4000 rpm. It just started doing this. What say you all regarding the cause? 2 liter fuel injected motor.

I recommended checking the cam boxes for excess oil pooling...I would expect the new valve guide seals to stop the flow of oil into the valve train, but can't think of much else that would cause this unless the cam boxes were full of oil above the seal level (I'd still expect it to be constant). He also said he has a distributor oil leak, but I can't imagine the smoke being intermittent if it has a constant leak.

Ideas?

[bradartigue]

The distributor can leak onto the manifold, which pools, then burns. It usually smells though and leaves oil in the wells when you park. Barring having way too much oil in the car (which can do some goofy stuff) it may have an improperly installed seal on an intake valve. Exhaust side usually doesn't do this, even without seals (early cars had no seals).

[So Cal Mark]

sounds like the distributor leaking onto the exhaust

[spidernut]

The way he is describing it is that there is no exhaust smoke at all, then a big "poof" of smoke. A leak onto the exhaust manifold would be constant I believe. I might need to follow him to ensure it is coming from the tailpipe and not from elsewhere. Thoughts?

[RoyBatty]

John,
My leaking distributor seal did just what you are describing as others here have mentioned.
The leak makes a puddle in the base of the distributor which then drips a little at a time onto the exhaust.
Take a look at it.

[4uall]

for what it is worth here is a great link if it is indeed the distributor

http://www.fiatspider.com/f08/viewtopic.php?f=9&t=10400

[bradartigue]

The way he is describing it is that there is no exhaust smoke at all, then a big "poof" of smoke. A leak onto the exhaust manifold would be constant I believe. I might need to follow him to ensure it is coming from the tailpipe and not from elsewhere. Thoughts?

You'd think that but it doesn't work that way. It's almost like it has to build up to a certain point and then poof. Likely pressure buildup behind the seal before it expels its contents.

[spidernut]

Brad...that's more along the lines of what I'm thinking too if it is the distributor seal. He's replacing the seals to see if that fixes the issue.

[bradartigue]

Brad...that's more along the lines of what I'm thinking too if it is the distributor seal. He's replacing the seals to see if that fixes the issue.

Unfortunately it may be a replace-check-replace-check kind of process. That area around the distributor can look clean as a whistle and you drive for a while and the junk burns...then the junk disappears when you check.