pp000830

Never noticed this, yet a mechanic years ago once mentioned the car seems to not pull as it should. I may have never known how it should feel.
Just checked one of the actuators on a whim and stumbled across the issue.
Andy

bcameron59

ToSi, according to workshop manual the recirc door & vacuum actuator are an integral unit, ie can't buy / install just the vac unit by itself.

Is that what you found? Or were you able to source & replace just the vacuum unit?

HiWind

Andy thanks for the headsup!

Bill may I ask - how many are there on the pre-VRAM?

OverBoosted28

Does anyone have the schematic for a TT?
thanks

Bill Verburg

3 they are the same as in the diagram I posted but don't have the 2 for the vram tubes(3a & 2) they also lack #1 and associated plumbing

Bill Verburg

That was my indication, flat at the top.

I smoked the manifold , found a few leaks and also doubled the vacuum capacity. The one under the dash escaped detection until I had a really good shop dyno the car and then look into it as you could see that it was falling flat at high revs. They found the leak under the dash which was missed by myself and 2 other shops. As part of the repair they added a check valve to prevent a repeat. The whole repair took less than 30 min. to complete once the leak was found. The next dyno was proof of the damage that was being done.

Steve Weiner-Rennsport Systems

I'd wholeheartedly agree with Bill on this. Pressurized smoke reveals the source of any vacuum leaks and the tricky part is knowing where all the vacuum-operated components are in the whole car.

FWIW, we always replace ALL of the little rubber vacuum fittings in the engine compartment whenever the engine is out for a top-end or complete rebuild. Such items do deteriorate over time from heat & age and can be the source of all kinds of running issues.

ToSi

In my case, the recirc actuator was OK (a pin in the linkage had broken). It was a couple of years ago now so don't remember exactly how the actuator was mounted, but from the pictures in this thread -> https://rennlist.com/forums/993-foru...ml#post9649661 , looks like while it isn't designed to be serviced, you might be able to disassemble from the bracket.

95_993

Anyone have a pic of the location under the dash? Sounds like cars now 20 yrs old, it just makes good sense to go ahead and replace before a problem occurs.

pp000830

Interesting the local BMW dealer called me back as the equivilant BMW part number fits a car only sold in the EC. I guess I will need to call my friend in Muchen to buy one for me if I want the part.

HiWind

Andy I'll check if they're available here as we make most of the 3 series cars here ...

when smoking the intake do you just introduce the smoke to the intake airfilter opening?

axl911

It is not fun chasing vac leaks. I bought a $40 smoke/fog machine from Party Central. It worked okay. What ended up being the most effective was to simply pressurize the intake with air to about 5 psi. Then use the smoke machine around the area of testing and watch as the leaky area swirl the smoke!!!

mpruden

That's a good question. Based on my quick research, you have to seal the intake completely, then apply low pressure smoke to the sealed intake through one of the vacuum lines.

I'm wondering how best to seal the intake (plastic wrap over air filter?) and where to introduce the smoke (will any easily accessible line do the trick?).

Also, you'd have to build a low pressure smoke machine. There are DIY examples floating around the web. Some are quite humorous.

bcameron59

THIS sounds like a good idea!

x50type

here you go...