Exhaust Leak Considering Welding
 

1995 Civic EX, B20b block, 1.8L DOHC head, CRV exhaust manifold that connects to '92-'95 EX catback exhaust.

Can hear and smell an exhaust leak between the distal portion of (CRV) exhaust manifold and proximal end/flange of (EX) catback exhaust. There are two "O" shaped seals at that joint and I replaced them about a year ago along with new bolts and nuts. I'm considering bringing it to an exhaust shop to have that joint welded shut ($50) to avoid this issue. Is there any downside to this?

Whenever I need to do exhaust or head work that involves removing the exhaust I unbolt and remove the exhaust manifold from the head rather than the three bolts at that joint described above,

Re: Exhaust Leak Considering Welding
 

I don't see why that would be a problem but I am not familiar with that setup.

Re: Exhaust Leak Considering Welding
 

Thanks GolNat. Due to bad weather this week I scheduled the exhaust shop next week. In the meantime I ordered Honde OEM gaskets in case welding can't be done. Looking back I think I used Felpro exhaust gaskets last year. The exhaust bolts/nuts that I installed last year are still tight so it doesn't look like they are the issue.

Re: Exhaust Leak Considering Welding
 

Maybe the Felpro was the issue on why they didn't last long. Welding it would still be a good solution so that way you don't have to worry about it again. I hate doing the same thing twice!

Re: Exhaust Leak Considering Welding
 

If there is too much rust, welding might not be possible.

If so try JB weld high heat epoxy.

Re: Exhaust Leak Considering Welding
 

I spoke to the shop owner and his idea is to weld inner diameter pipes into that joint. However, being that it's two smaller diameter (rather than one larger one) at that joint I'm not sure that decreasing the diameter is a good way to go?

My initial thought was that he would weld the outer perimeter of that joint which is shown in the pic below:

https://cimg9.ibsrv.net/gimg/www.civ...262986984e.jpg
I have a manifold and not this header. Just a reference for the joint I'm referring to.

Re: Exhaust Leak Considering Welding
 

Turns out the studs have backed out. Is it okay to use two nuts (lol) per stud? The stud doesn't have it's own hex drive or other area to tighten it so my thought is a second nut may help the stud achieve proper torque.

Re: Exhaust Leak Considering Welding
 

As long as it is tight and leak free I don't see why that would be an issue.

Also the smaller pipe in between the 2 would be a restriction but I don't think it will matter much for a stock Civic engine.

Re: Exhaust Leak Considering Welding
 

Thanks. I decided not to have any welding done and I may use copper anti-sieze as it has a temp range of -40F to 1800F. I know anti-sieze sounds counter-intuitive but the paste should promote extra compression on the threads to help keep the studs in place.

Update:
I called Permatex technical support and the person I spoke with said the copper anti-sieze will not help to keep studs in. However, he did recommend Permatex Ultra Copper Maximum Temperature RTV Silicone. He said, although it has a -40 to 700F temp rating he has used it himself (has a '99 Civic EX) on the same studs. He also said he's received feedback from others stating it works well for exhaust studs.He also agreed that using two nuts per stud should help.

Re: Exhaust Leak Considering Welding
 

Nice!! Always great when customer service is helpful and even has personal experience. I would definitely give that a try and see how it goes.

Re: Exhaust Leak Considering Welding
 

I added the copper silicone (which is the color only, no copper..per tech) and used two nuts per stud which did effectively drive the stud in well. Kept the felpro seals in as I didn't want to fully separate that joint. The exhaust has shut-up it's shuttin' up (for now anyway) so, hopefully it holds.

Re: Exhaust Leak Considering Welding
 

genuine seals or replacements maybe ease your issue