Sucking Oil up the Vapor Hose - flooding airbox

[yopurp]

OK, guys. Not the drive home I was hoping for. I picked up my car after it had been driven and inspected for a PPI, and drove 30 miles home. Well, almost home. I stopped a few miles from home to fill it up with gas when:

White smoke started pouring out of the engine bay. To make a long story short, the car is now in my driveway. Here is what I'm observing:

1 - when the engine is cold, it starts up an purrrrs.
2- after driving it and warming it up, the airbox literally fills up with oil, being sucked in from the oil vapor line (upper line in pic). It drains down the bottom condensation hose to the heat exchangers, explaining the smoke. This is not just a small amount of oil. It literally fills up my air cleaner housing about 1 inch deep in the back lower corner (through the hold at the back, lower right - see second pic). Its sucking enough oil into the intake to make the engine pop and backfire and eventually die. Then I drain the oil, let is cool, check the oil levels (looks fine???, pressure a little low, but now I"m not trusting the sender), then it starts fine.

So, I'm thinking something is blocking the lower oil feed (lower hose in Pic), or in the filter to create enough of a vacuum to pull ~1/4 quart of oil into the airbox. Any ideas? This engine has 30 miles (break in) on a total rebuild, along with a 12 month restoration (that's another story). Anyone have any ideas?

[yopurp]

Pic one - hoses

[yopurp]

Pic 2 - small hole visible in back - connected to upper vapor oil hose in pic one. When I crank the starter, oil gushed in.

[69Sman]

Chris, so sorry to hear of this! I know how excited you must've been to finally get the car back! I wish I could help diagnose the problem, however, I HAVE NO IDEA! SOMEBODY will chime in soon with some help, I'm sure!! I certainly HOPE it is something very minor, and you'll be on the road soon!!!!!

[sundaypunch]

It sounds like it's overfilled and blowing oil out the breather. I can't imagine that is actually the problem as they should know how to properly fill and check the oil. Did you verify it has the proper amount when it was warmed up? It should read low when it's cool (as you know I'm sure).

[roblav]

Sounds like you have too much oil in the tank. Check it warm while idling.

[admin_old]

Too much oil in the tank (that is, it's at "full") and/or too much blow-by (crankcase pressure). If it's the former, drain a quart from the tank. If it's the latter, it might be rings that haven't seated yet. Actually, at high speed, normal blow-by can cause this too, especially if exacerbated by too high oil levels. Some folks interpose a catch can in the hose between the oil filler tube and the air cleaner housing. The catch can helps separate the oil/fuel vapor into oil and vapor. The oil settles to the bottom of the tank where you can drain it periodically. The vapor gets sucked up into the intake.

Sherwood

[lbritish]

could be an issue with the piston rings not being right....... making too much crankcase pressure... or possibly a defective PCV valve? not familiar with porsche engines very much but some of the "american brands" with this type of symptom is usually something wrong with one of those two things...

[admin_old]

No PCV in 911 engines; just a breather hose from the oil fill tube to the airbox.

Here's a quick check. Bring to operating temperature, then remove the oil filler cap and rev the engine. Do you see a lot of smoke coming out? If so, that's blowby. Consult with your engine rebuilder and see what he says about seating the rings.

Sherwood

[silver911]

Chris,

Very sorry to hear of your problems.
I know how excited you were to have a perfect return of the silver beast...

I'm no expert but the high oil level combined with a tight engine may lead to oil going where it really shouldn't.

I've had similar oil smoke when its very hot out..south of France in August after a very hard run and you back off, a huge cloud of smoke from the engine and then nothing.
Oil levels and pressure were good, so I thought but the expert said I had too much oil for the temps I was runnig in and should drain about 200ml for 'comfort'.

Hope that helps a little.

Keep us posted.