Leaky Donut Exhaust Gaskets*#*##*

[Timothy B.]

Re: Leaky Donut Exhaust Gaskets*#*##*

My observation is that these aftermarket exhaust systems don't use the donut sleeve, this sleeve is made into the reproduction header exhaust pipe.

On original GM systems the sleeve centers the donut inside the exhaust manifold as well as the header pipe and keeps the donut from being cocked somwhat. It could be possible this is the reason the packings blow out.

This sleeve is important on the heat riser side because if the donut and header pipe don't stay centered with the exhaust manifold the heat riser valve will not open/close freely.

[John L.]

Re: Leaky Donut Exhaust Gaskets*#*##*

Joe:

The factory exhaust pipes had this sleeve part welded into them so its often overlooked as not needed. The ceramic or other donuts seems the better way to go.

[Timothy B.]

Re: Leaky Donut Exhaust Gaskets*#*##*

Just to be clear, my experence is that the GM systems need the sleeve. The aftermarket systems have the welded sleeve but it does not locate the header pipe like the sleeve because the welded part does not extend into the exhaust manifold.

[Tom R.]

Re: Leaky Donut Exhaust Gaskets*#*##*

Tom-----


It takes a while for the composition packing ("donut gaskets") to "loosen", but they will. The jam nuts will not prevent this because they only prevent the nuts from backing off. That's not what usually causes the loosening. What causes it is deterioration and "shrinkage" of the packing over time and repeated heating and cooling cycles.

Thanks Joe. I have successfully used fiber gaskets over the last 45 years on my Chev exhaust systems and never had a leak. I guess that's why they kept making them. I also have found that the brass nuts with jams work or me too. Lucky I guess.

[Joseph K.]

Re: Leaky Donut Exhaust Gaskets*#*##*

I finally took your suggestions and decided to try the metal donuts. As I took the pipes down I found out why you should use the fiber donuts. see the attached picture. This after only 1,000 miles on the car since the rebuild. They might have been made in China, but I could not believe what I saw when I took them apart.
Joe

[Joe L.]

Re: Leaky Donut Exhaust Gaskets*#*##*

I finally took your suggestions and decided to try the metal donuts. As I took the pipes down I found out why you should use the fiber donuts. see the attached picture. This after only 1,000 miles on the car since the rebuild. They might have been made in China, but I could not believe what I saw when I took them apart.
Joe

Joe------


Did the forward exhaust pipes have the extensions in them which, among other things, protect the packings from direct exhaust heat contact?

In any event, many of the products which used to contain large amounts of asbestos (and, for good reason) now use "substitute" materials. In many cases, these might be quite a bit inferior to the asbestos. This might be one of those cases.

[Jim R.]

Re: Leaky Donut Exhaust Gaskets*#*##*

On my 65 365 i have used the sintered metal without problems, i did not use the exhaust centering sleeves for the reason of making that area in the pipe and exhaust manifold smaller inside diameter.

[Dan D.]

Re: Leaky Donut Exhaust Gaskets*#*##*

FYI, I just bought 2 at the local Advantage Auto store. Did not have in stock, but had them the next day. He knew exactly what they were. 2-1/2" = $5 ea.

Are the heat riser gaskets prone to failure too? I could not get these in sintered metal. -Dan-

[Paul L.]

Re: Leaky Donut Exhaust Gaskets*#*##*

I really have to disagree with some of what is being said here. My former 1979 is on 10 years with graphite matrix donut gaskets with no problems. My former 1967 went the six years that I owned it with no problems. I replaced one today on my current 1974 with a kit from NAPA that included brass nuts and lock washers. I do not anticipate any problems.

The donuts are a tapered fit on each end to allow for flaws in alignment inherent in any exhaust system. But when they are aligned properly and clamped down tightly, and evenly on each of the three studs, they don't move.

This one on my 1974 gave up after years of service. Nothing else had loosened. In fact as you can see the nut did not loosen and the stud screwed out of the manifold. Not like when I replaced them on my 1979: three studs snapped off...that was a treat to repair without a torch! I just gave up and went to a muffler shop. Those guys know the right shade of red to get them out.

(thumbnail)

[Joe L.]

Re: Leaky Donut Exhaust Gaskets*#*##*

FYI, I just bought 2 at the local Advantage Auto store. Did not have in stock, but had them the next day. He knew exactly what they were. 2-1/2" = $5 ea.

Are the heat riser gaskets prone to failure too? I could not get these in sintered metal. -Dan-

Dan------


The tri-hole heat riser gasket is not available in sintered iron. These gaskets usually are not a problem. However, I prefer the type with metal shielding around the perimeter of the center hole.

[Dan D.]

Re: Leaky Donut Exhaust Gaskets*#*##*

Thanks Joe, I will go with what I got. -Dan-

[Paul L.]

Re: Leaky Donut Exhaust Gaskets*#*##*

On my 65 365 i have used the sintered metal without problems, i did not use the exhaust centering sleeves for the reason of making that area in the pipe and exhaust manifold smaller inside diameter.

How did you make out last summer with the sintered steel donuts and no sleeves?