Installing used exhaust with rusted flanges

[joebor1776]

Hi,
I just purchased a used turbo-back stainless exhaust system. It has some rust on some of the flanges and one of the flanges on the cat is slightly bent. I got some new gaskets and I sanded off as much of the rust as I could, but it's not going to be a totally smooth mating. Is this going to be OK, or do I need to go somewhere and have new flanges welded on? Or, can I double up on the gaskets, or maybe use high-temp RTV to help seal in the gaps?

Thanks!

 

[turboAWDfanatic]

I recommend new flanges. Shouldn't cost too much if you know a good shop. You can put better flanges on too if you want to upgrade.

http://www.roadraceengineering.com/flangesandgaskets.htm

 

[joebor1776]

I was afraid you were going to say that. Probably better to do it right and not have to deal with leaks, I guess. OK, thanks!

 

[NATAS]

You may as well try some good sealants first. Copper spray or high temp RTV ftw. You could double up the gaskets and use RTV too haha. I've seen some janky ass set-ups with guaranteed bent flanges and they sealed fine with a little coaxing. That's if you're on a budget, and since you're buying old rusted parts you probably are, so hold off on the new flanges unless you can do them yourself. Use that option as a last resort IMO.

 

[tlikethedrink]

i think you should be alright.

 

[Menacing talon]

Id say start with the cheaper option,that being the gaskets and RTV,and if that doesnt work out for you,then get the new flanges

 

[joebor1776]

Thanks, I think I will just go ahead and try it first and see how it seals. I got some quotes on new flanges and am hearing 25-40 bucks per flange! Yea, I'm definitely on a budget--having a wife and kids makes juicing up my toy car low on the budgetary totem pole . I appreciate all of your advice.

 

[roadrunner2176]

If you have a hand grinder use that to remove any remaining rust. Flap wheels work well at removing rust. As for the dent, if its small and on the flange itself it might flatten out when you bolt it down. If it worries you that much, have someone heat it up and straighten it; it shouldn't cost but a few dollars if you have someone do it for you.

 

[joebor1776]

OK, thanks. I used a heavy grit disk on my random orbital sander (yea, I know, wrong tool!), and that helped a little. I guess I need to get a hand grinder. Thanks for the advice!

 

[romeen]

Use some Ultra Copper RTV on both side of the gaskets and you should be fine. I have done this on some slightly warped flanges and it worked perfectly.

 

[My1GLaser]

I have had a bent flange in the recent past. I made my own exhaust and when welding the flanges they tend to bend with the heat. (Cheap 5/16" midas crap) I just took it over to my bench vise and put it on the "anvil" portion of the vise. (The flat part right behind the jaws) I hit it with a 3lb sledge until it was straight.

Oh yeah, you can do this when its cold as long as it is less than 1/2" thick it won't be too hard to straighten.

As for the rust, a surface prep kit ($12 @ harbor freight) works great with an air die grinder.

 

[joebor1776]

Thanks for the advice, I will try that. The bent flange is on the cat though--I'm afraid to bang that up too much. I just looked down into it and the mesh stuff inside is cracked already. BTW, just got my old exhaust off--came off all in one big rusty piece.

 

[My1GLaser]

I don't know if they do the "sniffer" emissions test in your area, but you could always run a "test pipe" instead of the cat. Ebay is a good place to find those or you could make your own with some pipe and flanges. There are also some high flow cats on Ebay if you want to try that. I am running one on my other car and it seems to be fine after a couple years.