My 66 Galaxie 390 has continual issue with the passenger side exhaust donut leaking after some 500 miles. I tighten it up, and in some 500 miles, leaks again!! At 1500, need replacing. I suspect the major issue is the donut I get is about .08" to large to fit snuggly around the inner stub pipe. So tightening the 2 nuts only mutilates the donut. My current attempt is to use a smaller donut, slice it, work it over the inner stub pipe, fill the gap with high temp silicon, let it dry, tighten, hope for 600 miles!!

I would have a proper sized donut machined from copper, but that may not seal very good.

Any thoughts??

Tom in VA

 

Looking at Rockauto, all the manifold to front pipe gaskets for the 390 are 2 1/32. If that is too big, perhaps you could sleeve the inner pipe with a wrap of shim stock. There is a 2.00 gasket sold for the 289 and 200, maybe those would be a better fit. How stable is that right leg of the exhaust? Could it be in need of additional support to keep it from moving?

 

Thnx M66. I will buy some 2.00.

I see my problem - the short stub pipe Waldrons puts in is not expanded to be the proper diameter for a good grip on the donut's inside diameter. I bought a short section from another supplier (stevetrekker) on eBay, that has the correct expansion.