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jeffkay1723 · Joined: 23 Nov 2010 Posts: 21 Location: Burbank,CA

So I am removing my 931 engine for a refresh. I find things done by previous, devious owners. This one has me. I have removed the head in situ. The waste gate hose coming from the top is metal and then goes to a rubber hose and back to metal line but then goes nowhere! Where is this end supposed to go? Could it have been a vacuum leak? I can't find any pix of where this metal line terminates though it looks to go to near the distributor gear housing... This is a 1980 stock engine.

I also found two little lever switches on the manifold that may or may not be aligned/operational. What is the purpose of these guys?

Thanks, Jeff

stevekat · Joined: 19 Jan 2008 Posts: 719 Location: Los Angeles, CA

This hose should have a female nut around a fitting that attaches to a male fitting on the crossover pipe that carries the boost charge over the top of the engine into the throttle body.

If this hose was disconnected, and you are taking your head off because the engine melted down - and this was disconnected before there was any problem, you can bet this was the cause.

This hose and the pressue from the crossover pipe is what actuates the waste gate. Without this hose attached, there is no functioning waste gate. Unlimited boost for all intents and purposes.
_________________
"Never get out of the boat. Absolutely goddamn right. Unless you are goin' all the way."

Gone to new home: '81 924T, US version, CGT Intercooler, UTCIS-PT, Euro DITC, Greddy Trust MBC, Forged Fuchs Flat Dish 6's, Factory Recaro's.

jeffkay1723 · Joined: 23 Nov 2010 Posts: 21 Location: Burbank,CA

I meant hose from top of waste gate, not top crossover tube...

Smoothie · Posted: Sat Feb 26, 2011 4:03 am Post subject:

Top-center of WG is a vent - some got a small vent cap, some got a hose that goes nowhere. Sounds like not a problem.

_________________
"..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

stevekat · Joined: 19 Jan 2008 Posts: 719 Location: Los Angeles, CA

Ah, my bad, the hose from the top is usually a vent. The hose to the lower side of the waste gate transfers actuating pressure.

The hose to the top vent is often alternatively used to hook up a manual boost controller using counter-pressure.
_________________
"Never get out of the boat. Absolutely goddamn right. Unless you are goin' all the way."

Gone to new home: '81 924T, US version, CGT Intercooler, UTCIS-PT, Euro DITC, Greddy Trust MBC, Forged Fuchs Flat Dish 6's, Factory Recaro's.