Porsche Enthusiasts Club Forum

After all my good work cleaning the cam covers, I have developed a massive air leak under the inlet manifold. It all needs to come back off again!!!! So, I'll start again and strip it down when I get a chance. Once again it happened on the speed bump right outside my house. My rule of thumb is, if I get over the speed bump, I'll get to where I'm going. The only thing I can think caused it was a bit of ice in the air line, causing it to blow off. I'll know when I find it.

If the air pipe you speak of is the vacuum source line coming back to the spider I have changed this without removing the inlet.

Is this what we're talking about?

I can't see it? I can only hear all the air from under the manifold. When the weather is better I'll have a better look. I spent as much time as i could, out in the rain, with a torch. Still couldn't see anything. I looked on Richard Armstrongs site, he has some very good pictures of the manifold off. Where is the spider you changed, front or back?

I had the same noise, however we had the car shifting very hard due to the lack of vacuum not being there to soften the changes. If this isn't happening to you the leak isn't from the source pipe under the intake but maybe one of the lines coming off the rubber vacuum spider at the back of the engine to the other vacuum related components. It could even be the separate HVAC vacuum system giving you grief.

At the back of the engine there is a five way rubber splitter, with the source of the vacuum coming from underneath the manifold. After removing the MAF and the rubber elbow I could JUST get my arm in and reattach the line to the intake manifold, and the vacuum was returned.

Hope this is clear!

I'm getting rather hard shifting, like you experienced. I'll get the car inside and have a look, my 944 is in my friends garage and it needs to come out before I can put the 928 in. Thanks for the info'. I really don't want to take all the stuff back off again.

I can recommend getting a vacuum system tester or just a gauge. If the vacuum is non-existent then it could just be this line slipped off and you have to put it back on!

Cheers rwaky, I think my mate has a vacuum tester. I'll " borrow " it while I'm in the garage. He works on Merc's with the same gearbox in them, so he claimed he might know where the vacuum line goes. Once I've got it inside I'll have a good look.

Sounds like you have done what I did. Just see if there's any vacuum whilst running at all....

No air leak to be found, but when carb' cleaner was sprayed under the inlet manifold on the drivers side, it affected the tick over. So it looks like this again,

There seems to be an issue on this side,

I've ordered a few parts from OPC. Mainly all the vacume hose, connectors and elbows. The hose I forgot the last time and seal kits for the injectors. There are also seals on the bolts that hold the manifold down, so they are ordered too.

The new wheels and tyres are going on too, but that's a different topic.

You haven't got a warped manifold or a hairline crack somewhere have you ?

I'm going to have to put a steel rule on it in the morning. A hair line crack is going to be hard to find. I have a magnet, so I could NDT it?