Exhaust Donuts, leaks, 66 Galaxie but applicable to many

[68LTD]

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

[Bhigdog]

Have no idea what yours are made of or the configuration of the joint but I made donuts for my Vette from 6061 aluminum. Guessing any alloy would work. They're holding up well and no leaks so far...............Bob

Edited October 2, 2022 by Bhigdog (see edit history)

[68LTD]

Thnx Bob, I might do the same. 

 

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. , see pic. 

[68LTD]

Update :  My 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, ....has lasted 1200 miles so far, seems good, I have not crawled under to check torque on studs, but sounds fine.  Happy camper. 

[Mark Shaw]

A few years ago, I bought three 4' X 4' panels at the Portland Swap Meet that were full of exhaust donuts and gaskets.  Several seem to be graphite with metal inserts like the one shown below.  Send me your measurements and I will see if I can help.

[68LTD]

Well, at about 1600 miles. slight leak started, my lil red silicon gap filler was blown out.  I will share pics of next revision....and I will continue to look for high temperature urethanes that could be used to 3D print a proper size donut.  But maybe 1200-1400 miles will be several years for you.