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macBdog · Posted: Tue May 22, 2007 11:52 am Post subject: Cleaning the crankcase breather

So I have read about the benefits of cleaning the engine breather on the side of the block but I am reluctant to pour gasoline down into my crankcase as has been suggested. How can you be sure all the gas is expelled from the sump afterwords?

What is the correct procedure? Can you spray some other bearing-friendly solvent under pressure from a degreaser gun or do you just pour it in and hope it breaks up the gunk?

If there are some good additions to this thread we can move it to the how-to section.
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1979 931 with a 350 chev
1973 911E with EFI

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11732 Location: PacNW

Well, if the drain plug is off, you can bet that whatever drops of gas are left won't effect 6 quarts of oil once you refill. . .
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Min · Posted: Tue May 22, 2007 3:02 pm Post subject:

Personally the whole pouring solvent in my motor thing gave me the willies, so I just removed the breather with a screwdriver, and removed the mesh from it completely (using a drill and some pliers). In my case, it was so plugged that there is no way solvent would have fixed it anyways

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

macBdog · Posted: Tue May 22, 2007 3:55 pm Post subject:

Tigger937

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

Nobbi · Joined: 24 Aug 2006 Posts: 1393 Location: Germany

Hey their,

i replaced that 30 year old hose that is att. to the breather, and my car is much easier on high revs. then before.I could breath out better!!
I didnt touch the breather itself because in a book they wrote its not to fix with motor installed, or dismantled.See explo.view in repair manual.

Nobbi

Min · Posted: Wed May 23, 2007 1:53 am Post subject:

Min · Posted: Wed May 23, 2007 1:54 am Post subject:

I also noticed a very nice improvement in performance clearing out the breather. I never hooked it back up to vaccum though, thinking about getting a small vaccum pump.

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

It's a good idea to use a steel-reinforced hose for the breather - just to make sure it doesn't get squished or collapse.

When I cleaned mine, I just tapped on the ground until the black muck stopped coming out, then let it sit in gasoline overnight. Seemed perfectly open after that.
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

Min · Posted: Wed May 23, 2007 2:51 am Post subject:

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11732 Location: PacNW

Well, I am staring at the PET and not really seeing what you guys are talking about. Could you elucidate for me? Is it a different setup for a 931?

I am wondering if I have the same issue, as my oil cap is leaking even with a new seal. . .
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Min · Posted: Wed May 23, 2007 4:11 am Post subject:

Smoothie · Posted: Wed May 23, 2007 5:41 am Post subject:

The breather itself (the mesh-filled metal cap at the rear-side of the block) is the same between 924NA and 931. After that, the NA just has a hose with a restricter orifice and dumps back into the intake (as I recall some attach at the airbox while others attach further downstream at a boot between the airbox and throttle.
-While the outlet of the breather on the 931 goes to the air-oil seperator which has a drain to the sump and an outlet to the airbox. If the breather on a 931 gets completely clogged, then the oil drain from air-oil seperator to sump will want to become your breather and you might end up with oil being sent the wrong way - up that drain + up the drain for the turbo on the other side of the engine. Most likely you'd just have a blocked, nonfunctional breather-air-oil seperator system though, rather than a major disaster with large amounts of oil overflowing the seperator. Plus you might have leaky seals and/or leaky oil filler and dipstick + you might have some smoking if the oil's backed up severely on the turbo drain side.

A quick unscientific test would be to detach the breather line from the air-oil seperator and blow through it with the oil fill cap removed then make a guess as to whether it's flowing freely enough or not. (This would be slightly complicated by the earlier 931 breather setup that used a Y pipe to connect the turbo breather and crankcase breather - in that case you'd have to disconnect the breather line at the Y so you could blow through just the one line that leads to the breather "cap".)
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK