Exhaust leaks from ALL flanges....

[jsoderbe]

Hi,

Can anyone please tell me how I managed to get exhaust leeks from ALL flanges?

I have a 1972 911 with a 3.0 sc engine. The only obvious thing I can think of is that I back-dated the exhaust with the 1972 heat exchangers. Could it be a mismatch with the thin flanges?

other than that, what could I have done wrong?

Any answers would be very appreciated.


Thanks,

Johan

[johnsjmc]

If the studs were designed for the thick flanges ,the threads probably end too soon .You have bottomed out the nuts before compressing the gaskets. Add some washers and try again.

[911Freak]

Did you re-torque the Heat Exchanger stud bolts after your 1st drive/heat cycle after the H/E install? There is another thread here just the other day where guy didn't re-torque his exhaust after installing them...they were all loose making massive exhaust leaks.....

[Flat6pac]

A 78/79 3.0 is a thin flange exhaust. The 72 stuff will show warped flanges. Sometimes its necessary to double gasket the exhaust flanges or use the 77 gaskets that are a metal fiber and a little thicker.
If the 3.0 is 80 to 83 there is long studs that need to be accounted for and sometimes you need to use a 10mm nut to make up space. If you try to move up the stud sometimes the threads are shot from rust inside the thick exchangers of the 3.0 heat boxes.
Bruce

[jsoderbe]

Thanks guys,

it seems like Johnsjmc was right, too short thread left, especially on the allen nuts.

The exhaust sounds better, but still not entirely quiet, so I think I will have to go with Bruce's suggestion. Maybe I'll machine the flanges at the same time.

Thanks guys, and Pelican!


Johan

[johnsjmc]

I use a smear of muffler cement on the gaskets. Not too much as you don,t too much to slop out. The kind that hardens with heat .