Billowing smoke on left turns.

[autobonrun]

I'm trying to find what may be causing large amounts of oil smoke to come into the cabin, especially through the defroster vents when I make hard left turns. It doesn't happen on acceleration, hard stops, or hard right turns; although there is a small amount that is generated on right turns also. It's bad even with the top off. The car has sat mostly for a couple months while I updated the interior. I've wiped the airbox down and there was very little oil pooled in it. I do notice some oil that has dripped down on my SSI's but I don't understand why such a large amount of smoke is generated on left turns. I did drive it for an hour or so to burn off some of the oil but I still have the billowing smoke on left turns. Any ideas?

[juanbenae]

have you recently topped off the oil?

the oil that causes it is the oil spashing out of the oil tank breather tube. its high up above the oil tank and has a plug as best as i can describe as a metal shaving hair ball affair.. try a search for "oil tank breather" and you will get some good info. from what i recall if you lose the breather "plug", or over fill the oil it will exit the tube on left turns and drip on the exchaner.

scared the $hit outta me when it happened in my car.

[Joe Bob]

INSIDE? bummer....doan make no more left turns...%^B....

Hmmmm, any holes in the heating tubes or heat exchangers?

[autobonrun]

Mike, no holes in the exchanger. It's a fairly new SSI. With no left turns, I'll need to stay off the NASCAR tracks for a while.

K911SC, the top side of the engine is dry except the shelf under the oil filler neck. I followed your suggestion and found that the hose that connects the filler neck to the airbox is loose at the box. I'll tighten it and look for the plug you mention. I assume this is different from the flame arrestor that goes in the hose on the other side of the airbox. I checked the oil level and it is a little over the bottom mark where I try to keep it.

The driver side exchanger is pretty wet and the passenger side is a little wet. Looks like I need to get it up on jack stands and clean everything real good in additon to checking the filler neck hose.

I'm still not sure how the oil is getting into the vent system if the exchanger is supposedly sealed. I'll need to check the entire heating ductwork under the car for holes as well. At least the interior now looks good.

[Joe Bob]

I looked again at your original post....no metion of CIS/MFI or carbs...

On CIS there is a "brillo" pad in the oil line...it keeps oil ingestion down....on carbs there is a "puke" box....all are contingent on oil level...

"I" like to keep it a bit low on the dip stick when measured HOT on a level field....when running...

On ocassion I have done a 3 point turn on a country road after a hot run up the highway and STILL burped some oil into the intake.....run it hard and ignore the Harley guys laughing at ya.... it will burn off.....

But it shouldn't suck in the cabin....

Is there a cloud of smoke out the exhaust as well?

[juanbenae]

sounds like it may be something different then if both exchangers are soaked. scroll to the bottom of this thread and read john walkers answer. smoked, but just for a second

brillo,, kinda a meatal shaving hair ball eh?

you still have not mentioed your year 911, as mike mentions carbs or injection may vary your cause..

[autobonrun]

Sorry for not posting info on my car. I have a 1979SC with CIS injection with SSI exchangers and a Dansk dual out muffler. No smoke out of the exhaust inself, but it's entering the cabin and I can also see it in the engine compartment. It literally pours out of the defrost vents and the vents under the dash.

[Dan Morton]

I had the exact same problem with my 1970 after I had the engine completely rebuilt. After hard right turns smoke would pour into the cabin.

It was fixed by tightening the oil line connecting from the tank to the oil cooler. That was it! So check all oil lines!

-Dan

[sfmlaw17]

Check the heater tubes to the blower motor for cracks as well, smoke can get in there. My bet, leaking cam tensioner lines. Oil will tend to pool up near the housing and when you go into a turn, it will drip onto the top of the exchanger. Check those as well. Once it starts to smoke there, it can easily get to the vent system.

[autobonrun]

At least I have some areas now to start checking. I'm fairly certain the brass wool filled tube that goes between the airbox and filler neck is missing. The curious part is why it suddenly did this now and never before. Even with hard turns on the track I never had the smoke.

Anyway, I'll start checking hose connections and checking for line leaks this week. There is quite a bit of oil on the exchangers and I guess sitting for a couple months allowed it to build up.

At least this little episode did remind me to reinstall my fire extinguisher in the car. I had removed it to revamp the interior.

[autobonrun]

Here's what I found:

1) Valve covers were leaking oil on the exchangers
2) Oil tank breather line had come loose from the airbox
3) Right side cam tower line is leaking from both ends


All this was making it's way onto the hot engine or onto the exchangers. The real problem however was that the heater hose had come loose underneath the A/C unit. This was not visible unless the compressor was moved. So all the smoke from the engine was being sucked straight into the vent system. I don't know if it's just mine or all SC's, but the heater hose that goes across the engine connects to a second hose that extends through the sheetmetal to the exchanger. The open hose was right where the smoke was be generated!

So this time rather than just trying to push the two pieces together, I did it right by removing the AC mounting bracket (the back bolt is a real PITA) so I can access the connection and add a clamp (which was missing). Also, The valve covers have been replaced, along with the breather line.

All that's left is to replace the right side cam tower line while I've got the A/C out. I have no experience with the banjo fittings. Is it just a matter of holding the section below the banjo fitting and backing out the hollow bolt; and replacing the o-rings of course?
Anything to be careful of when replacing the cam tower lines?