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Exhaust manifold to downpipe connection


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Got a leak on the exhaust manifold to downpipe connection. It seems not to be seating good. I cut the exhaust after the downpipe and connected it before having the exhaust shop sleeving the cut part together. Seems downpipe and exhaust is not closing together correctly. I have one gasket between it. Any suggestions on what might correct it to close it tight and flush so not to leak. It is on my Goon 72 510. It is all old. I cut the pipe to get it to pull flush but I believe it is pulled to but on an slight angle causing it to leak. 

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Are the studs in good shape. Mine only had threads where the nut protected them from erosion.

 

The nuts when tightened will swing the down pipe into position. If hitting the floor or the exhaust system is not allowing it then the pipe will need to be bent to allow it to close this gap. It's kind of janky but a slice 7/8th of the way through with a sawsall might allow the gap to close then weld up the cut. The width of a sawsall blade will probably be enough, don't make a pie cut.

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What mike said.  Also is it cracked?  If not extract the bolts or studs and change them out. The nuts are a copper or brass and don’t up to will after 50 years.

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It's not hitting any thing I cut it so it would hopefully close correctly, it's not hitting anything. The studs have threads but it seems not to close up flush. I have a manifold I plan to get the bad studs out and put new ones in and correct brass nuts for it later and make sure it works before I install it later. I'll probably just come up with a solution to make it work for now so it does not leak. There may be some sort of obstruction not letting it mate up correctly.

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1 hour ago, edekalil said:

It's not hitting any thing I cut it so it would hopefully close correctly, it's not hitting anything. The studs have threads but it seems not to close up flush. I have a manifold I plan to get the bad studs out and put new ones in and correct brass nuts for it later and make sure it works before I install it later. I'll probably just come up with a solution to make it work for now so it does not leak. There may be some sort of obstruction not letting it mate up correctly.

 

Use washers to verify your guess before doing any thing irrevocable.

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9 hours ago, edekalil said:

It's not hitting any thing I cut it so it would hopefully close correctly, it's not hitting anything. The studs have threads but it seems not to close up flush. I have a manifold I plan to get the bad studs out and put new ones in and correct brass nuts for it later and make sure it works before I install it later. I'll probably just come up with a solution to make it work for now so it does not leak. There may be some sort of obstruction not letting it mate up correctly.

 

I would think that the pipe must be prevented from swinging into position.

 

One other thing. The down pipe has maybe 1/8" of pipe sticking up above the flange. This sticks up into the manifold so if there is something in the way it won't seat.

 

otASYRV.jpg

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  • 3 weeks later...

Got the spare exhaust manifold back from my friend at the welding shop.

 

IMG-20210426-162725.jpg

 

IMG-20210426-162730.jpg

 

He got the studs or what was left of them out in good order so now to locate a couple of set's of new ones for this manifold and the one I'm gonna take off to get the same thing done. I think the one on the car had a stud that was in poor shape and would not pull tight so letting it leak. I'll save it for the L20 B that will go in the 2 door sedan on the rotisserie. Any suggestions on where to get the set of studs with the long brass nuts.

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Measure and get longer SS studs that match a longer SS nut. Every time I take mine off it's like new.

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I'd think twice about using stainless nuts on stainless studs, especially on exhaust. Stainless on stainless might have a tendency to gall/seize, in the hot/cold environment of the exhaust system. Brass nuts with Never-Seize paste and SS or carbon-steel studs is what I'd consider.

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Well the only thing that might need to come off is the nuts. Mine look coppery or bronze, don't know what they are. SS when heated goes a straw yellow.

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I believe I've seen them sold somewhere and I believe there nuts are brass, not a 100% sure but we'll see. And the nuts are longer than a normal nut. And Mike and all thanks for the info.

Edited by edekalil
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Sounds like them. I thought I bought them but maybe off a Z series engine??? Pulled a lot of them apart.

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