DIY Exhaust Gasket?
 

I am sick of having an exhaust leak between my BEGI DP and my cat. I've got the dp off right now and discovered that it is actually a 2.5" exit vs the 2.25" on the cat. Hmm, what can I do here? The flanges are exactly the same size so a gasket should work. Is there some way I can fashion a DIY gasket out of something?

High temp RTV would work i'm sure but I really dont want the thing to be impossible to get off in the future. I'm doing some google searching and not finding anything. Ideas?

you can buy paper gasket material in a sheet and make one.

the stuff usually sucks though

Amazon.com: Mr. Gasket 9615 Compressed Gasket Material Sheet: Automotive

I just went to my little "mom and pop" Carquest auto parts store with the lower section of my Begi downpipe. They had a book with all kinds of exhaust gaskets with scale sized photos. Put the DP on a bunch of pics and found one that fit and they ordered it up. Full metallic gasket for like $7.00. I don't know if you can get that kind of service at the idiot chain stores that will insist on year make and model before they can sell you the right oil or something.:jerkit:

I may have to see if NAPA has something like this.

I'm also considering trying to use the reflective fiberglass stuff I used to wrap my heater tubes.

http://permatex.com/images/DisplayIm...otos/81878.jpg orhttp://permatex.com/images/DisplayIm...otos/80333.jpg

Never seen either of those before. Oh well, already back together and it leaks more than ever before. I'll fix it someday.

how hard is it to remove 4 bolts, smear some goo and bolt it back up?

Lol i've been working on the car all day and now I need to do my taxes. I'll try the goo this weekend. And there are only 2 bolts holding the dp to the cat, where are the other 2 you are referring to?

try the mr.gasket cut it your self sheets.

I don't think the gasket sheet material will work under that high of temps. Its more meant for intake stuff, coolant system gaskets, oil gaskets, and other things that don't see such high temps, not exhaust gaskets. I say just smear some Copper RTV on it and see what happens.

gasket sheet material says "exhaust gasket on it" and is made of stuff I can only imagine to be used as an exhaust gasket. Have you ever held one/touched one? If you do you'll know what I mean

I've got to agree with this, I used the Mr. Gasket exhaust material on my DIY Rx7 turbo, and it held up just fine. I really dont think a turbo miata's EGT's can come close to what the exhaust on my rotary was putting out ;)

I was thinking both sides. I've always used the above (mostly copper rtv) for my exhaust flanges. always works.



EVIDENCE:

http://boostedmiata.com/exhaust/exhaust005.jpg

I see what you mean, Brain. I'm only having issues with the DP-Cat flange. Hopefully this copper rtv will work. Is it difficult to remove later?

As to the Mr. Gasket stuff some of you mentioned...It was $20 for a sheet at Napa. I had a chance to stand in line long enough for me to realize that $20 was not worth it for an exhaust leak to me. Will try the RTV today depending on what my homework load is like tonight after class.

DId you see my post about just buying a metal exhaust gasket? Simple, removable, reusable, no mess, seals "less than perfectly flat flanges", cheap.

Yes, I should have responded to that. At the time, I needed something quick...not something that I needed to order. Now I dont want to remove my downpipe again to take it to the store =P The copper RTV should work but if it doesn't i'm going your route for sure.

I'm also looking fairly soon at welding up a new exhaust just using v-band flanges or something similar so...we'll see.

yeah, if you ever remove, just use a razor and scrape it off. It's just silicone that can withstand the heat.

coat both flanges liberally, mate, bolt up. done!

Ok, just did a half assed application of the copper rtv. It seems like everytime I work with RTV I do so in clothes that I dont want to get RTV on thinking i'll be tidy with it. Everytime, no such luck. Got this shit all over my shirt lol.

I've ruined many a shirts...and i always seem to get it in my hair.

Lmao, Just checked my hair. I've got pine needles rtv'd into my hair. This is a first. I did this very quickly in my driveway instead of in my garage so it'd have time to dry before I pick the gf up from school.

Luckily its not cured yet. Shower time.

Edit: no more leak. Thanks Brain.