930 Engine almost done! What do I do with this fitting?

cowtown · 09:55 PM

Well, after a couple months of just being totally overwhelmed with rebuilding this '77 3.0 930 engine (my first), I'm starting to get excited - I've got just about everything done and I think I'll be running in weeks not months now.

So I picked up an airbox assembly from a 3.3 turbo from Ebay, and am dealing with a small issue. Since it's from an intercooled car, it can't sit quite right to get the two top bolts (#51 in the diagram) lined up - the fitting (I'm pointing to it in the picture) hits the plenum.

1) What is this line for? I'm assuming it's 3.3-specific because my parts diagram (below) doesn't show it.

2) Will I need this fitting later, if I intercool this engine? I.E., if I grind it down a little and then plug it, am I ruining it for later use? I don't have the later diagram, unfortunately.

Thanks everyone for your ongoing help with this thing. I've made mistakes, but I've made a lot less than I would have without this board.

Colin

Emission · Emission's Garage

I just checked out my 3.3 in my '86.

From the airbox fitting you point to... a rubber hose (with cloth braid on the outside) drops straight down then to the rear (back bumper) of the engine. The rubber hose attaches to a metal pipe on the top of a oil reservoir (?) that feeds the turbo.

From what I make of it... it appears to be a breather line for the oil tank that feeds the turbo.

Anyone else care to take a stab?

P.S. - It appears to have nothing to do with the intercooler.

cowtown · 03-27-2003, 11:09 PM

Ah, OK, the turbo drain tank breather. Thanks for checking.

I definitely can't vent my turbo drain tank to that fitting (because there's no clearance with my non-intercooler intake plenum), but maybe I can run it to one of the other two barbs on the airbox. I was going to run that breather back to the main oil tank, but maybe this way would be cleaner.

How come the crankcase vapors vent back to the oil tank but the turbo oil tank vapors are burned, I wonder?

Colin

Emission · Emission's Garage

Yes, that make sense, it is the "Turbo Drain Tank Breather", of course!

I bet it is for reduced emissions...

dean · 03-28-2003, 04:27 AM

I think the turbo drain sump tank vent is a vent line to prevent vacume in the sump tank. The turbo drain tank is getting sucked out by the scavange pump and it needs filtered air. You could also put a little air breather on the vent line. On my car the turbo sump tank is vented to the back of the airbox

RarlyL8 · RarlyL8's Garage

I've got a 3.0 turbo (stock) air cleaner assembly if you are interested. They are quite different than the 3.3t units.

cowtown · 03-28-2003, 06:31 AM

Quote:

Originally posted by Blown
I think the turbo drain sump tank vent is a vent line to prevent vacume in the sump tank. The turbo drain tank is getting sucked out by the scavange pump and it needs filtered air. You could also put a little air breather on the vent line. On my car the turbo sump tank is vented to the back of the airbox

Dean, that makes perfect sense when I think about it that way.

RarlyL8, thanks for the offer. This 3.3 box looks like it will bolt on and work fine (with the exception of that fitting I mentioned) and I will no doubt want to intercool the car as soon as I can - I know how the turbo bug bites and won't let go. But If something comes up and I can't get it working, I'll drop you a line about your assembly.

Thanks everyone.

rick conrath · 03-28-2003, 09:56 AM

I have the same fitting on my 3.3 I am guessing that since the fitting on my air housing is plugged, and my air pump is gone, that it is air pump related.

cowtown · 03-28-2003, 02:52 PM

Quote:

Originally posted by rick conrath
I have the same fitting on my 3.3 I am guessing that since the fitting on my air housing is plugged, and my air pump is gone, that it is air pump related.

Rick, if that one's plugged, where is your turbo drain tank breather line going? Does it go to one of the two barbs on the other side of the filter box (on the flywheel side of the engine)?
Colin

rick conrath · 03-28-2003, 04:47 PM

Let me look tomorrow and I will try to give you a more intelligent answer. I know the breather hose from the oil tank comes off the back of the housing. I will look at the drain tank and get back to you .