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Flange gasket and RTV for exhaust leak repair?


Zed
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95 Pathy VG30E 5MT

 

Decided to tackle that exhaust leak at the flange between my y-pipe and mid-pipe. Yes, the leak that rusted the hole in my floorboard!

 

hole_sm_zps7qbmn6js.jpg

 

Anyway, the bolts are so rusted I’m just going to sawzall them off tomorrow (couldn’t even get a wrench on it - it’s just one giant blob of rust. I bought a Nissan gasket for this exhaust connection at the stealership, so I’m hoping the flange is still okay to put this thing in. It sure seems like a large enough gap that the gasket won’t do spit.

 

If everything checks out, I was just wondering if anyone recommends using any sealant - like RTV copper when I put the gasket in.

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The flange surprisingly is in decent shape. Just a bit of rust on the mid-pie flange (on the other side of the exhaust leak).

 

[Looking up - Front of engine to the right]

 

flange_sm_zpssff2dfcp.jpg

 

It seems like a donut is welded into the mid-pipe.

 

So, is sealant recommended in this service?

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Mmm donuts.

 

I have never heard of anyone using sealent on exhaust. The worst that would happen is it would burn off and you would need to take it apart and put a new gasket in.

 

Mine was leaking in the same spot. My flanges were not as bad as yours, but close. I used a felpro gasket from either Amazon or Napa, and it sealed the leak.

 

Try the gasket, if it doesn't work, then try adding sealent. If that doesn't work then it may be time for new exhaust.

 

Question, my exhaust lays on the crossmembers all the way back. All of the hangers are there and the rubber isolaters are all installed. Parts of the exhaust look somewhat new. Is this how Nissan designed the exhaust, to lay on the crossmembers, or did someone do a crappy job of replacing the pipes? It seems very weird and wrong to me to see the exhaust routed like that. Is yours the same way?

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My mid-pipe does not lay on the cross-member. I'm probably less than an inch above it.

 

But I just had everything passed the cat done at a muffler shop and they put a new hanger in for me - I can't remember if it sat on the cross-member before that.

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Prepped the flange and installed the gasket - like I thought still a thin gap.

 

The flanges seem to mate beautifully w/o the gasket, Go figure.

 

The exhaust leak is not nearly as bad, but still there.

 

Are those Felpro gaskets thicker, Citron? I think I could seal it up with another gasket and some wrap.

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I think they were about 1/8th inch. They are fibrous with some sort of metallic silvery coating. If I remember, the OEM gasket was a stack of thin metal pieces, right? If so, the felpro is thicker.

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Yeah, same multi-layered metal gasket that rotted out. I'll try the Fel-Pro gasket. Should be an easy job.

 

Thanks for the assistance Citron.

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Those flanges are rotted. The flanges should be like 3/16" thick. I would just replaced the Y pipe and intermediate pipe. They are not that expensive on rock auto.

 

Trust me you will be replacing gasket after gasket and no amount of rtv sealer will hold it together.

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I'll install the Fel-pro gasket today and see where I'm at.

 

The pipes may look bad, but they are actually fairly solid. If this new gasket doesn't help the leak, then maybe I'll look into a new y-pipe and mid-pipe.

 

I've read some horror stories about y-pipes not fitting. I'll do a bit more research on it. Thanks.

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Well, installed the Fel-Pro gasket. A little thicker and definite improvement. Placed a nice line of RTV Copper on the mid-pipe flange in there as well. There's still a bit of a leak at the top (where I had difficulties cleaning it up). Obviously, I should have taken care of this when the floorboard was open.

 

But after messing with it, Adamzan is right, the flanges are a bit thin around the bolt holes - preventing a really tight seal. So, this repair will have to do for now. I guess I'll start shopping for a Y and mid-pipe.

 

 

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One thing I did on mine was installed 2 gaskets, and place one with the ears facing up (so the parts with the bolt holes are vertical). What happens is the flanges bend ever so slightly so it never seals in the middle. This takes up the space without spacing it out further at the bolt ends.

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Hmmm. I think another Fel-Pro would definitely work placing it the way you describe.

 

I know I can make a decent temporary repair until I have to install new pipes.

 

Thanks for the tip!

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