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Old 12-01-2019, 03:35 AM   #1
siickwrx
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Default Exhaust Leak

Hey guys,

I'm having trouble with an exhaust leak. I have an invidia downpipe mated to a greddy catback (I believe its the Revolution RS). I put a 3" flat gasket between the downpipe and greddy catback but it seems like there is a gap on top and it's producing a fat exhaust leak. How do I get rid of this leak? Car is an 07 WRX

Thanks
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Old 12-01-2019, 09:43 AM   #2
shadowsports
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3in flat flange to flat flange?

Sometimes the angles don't quite line up.

What can help:

Using different exhaust hangers
Using a spacer
Using 2 gaskets

Soapy water to test the fix. Good luck.
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Old 12-01-2019, 11:15 AM   #3
BeastianSTI
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Quote:
Originally Posted by shadowsports View Post
3in flat flange to flat flange?

Sometimes the angles don't quite line up.

What can help:

Using different exhaust hangers
Using a spacer
Using 2 gaskets

Soapy water to test the fix. Good luck.
Quite right.

There are three hangers. I'd try to go into some theoretical thinking like:

If the back of the exhaust (2 hangers at rear) were lower, would that make the angle of the flanges line up better?

Same for the front hanger. That might need to go a little lower to enable the flanges to be parallel to each other.

I've also used Grimmspeed's exhaust gaskets to make things fit better. They're thicker so it makes it a little bit easier.
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Old 12-01-2019, 02:38 PM   #4
kopele
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I've good success with RTV gasket maker, it's a little messy but does a good job.
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Old 12-02-2019, 02:53 AM   #5
siickwrx
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Thanks for the advice guys! I put that red high temp rtv I had lying around on both sides of the gasket. It's working so far. Don't know how long that will last tho.
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Old 12-02-2019, 10:20 AM   #6
MortonCharbo
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I used a remflex 8006. It's just a thick graphite gasket that forms to the two flanges when you tighten them together. I payed 8 bucks for it on Amazon.


I tried the GS gaskets with no luck. I used the rtv stuff and it lasted about a week.
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Old 12-02-2019, 10:26 AM   #7
BeastianSTI
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Quote:
Originally Posted by MortonCharbo View Post
I used a remflex 8006. It's just a thick graphite gasket that forms to the two flanges when you tighten them together. I payed 8 bucks for it on Amazon.


I tried the GS gaskets with no luck. I used the rtv stuff and it lasted about a week.
I've used those too. Worked well in my case, but I think it's difficult to fix exhaust leaks if the flanges just aren't lining up.

@OP - if you want to share some pictures of what we're talking about, that could be helpful (of the flange currently, and maybe the tip of your exhaust).
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Old 12-02-2019, 12:26 PM   #8
raisingAnarchy
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Stick a shop vac hose in reverse flow setting in the tail pipe to test your fixes. That's how I did the leak troubleshooting on my Tomei expreme catback with those damn slip fittings.
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Old 12-03-2019, 02:59 AM   #9
siickwrx
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I'll try the remflex 8006 once my ghetto rtv fix fails haha. I'll try to post pics of the flanges whenever I get a chance to.
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Old 12-03-2019, 11:26 AM   #10
shadowsports
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Quote:
Originally Posted by siickwrx View Post
I'll try the remflex 8006 once my ghetto rtv fix fails haha. I'll try to post pics of the flanges whenever I get a chance to.
Soapy water, best way to check for leaks and easy too.
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Old 12-03-2019, 06:47 PM   #11
Jedi03
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get the seal for good gaskets from autozone...they are super thick and work great!
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Old 12-05-2019, 12:42 AM   #12
metalheadsunite
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Quote:
Originally Posted by Jedi03 View Post
get the seal for good gaskets from autozone...they are super thick and work great!
I am not sure what the Greddy catback uses but I have Invidia downpipe and Cobb catback and had to use the Grimmspeed adapter with a flat gasket on one side and a donut gasket on the other. Ended up fixing my issue.

Like here: https://www.subispeed.com/2015-subar...5-wrx-2015-sti
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Old 12-05-2019, 02:36 AM   #13
siickwrx
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Quote:
Originally Posted by metalheadsunite View Post
I am not sure what the Greddy catback uses but I have Invidia downpipe and Cobb catback and had to use the Grimmspeed adapter with a flat gasket on one side and a donut gasket on the other. Ended up fixing my issue.

Like here: https://www.subispeed.com/2015-subar...5-wrx-2015-sti
I actually have that adapter. Does the cobb catback have a 3" flange or 2.5"?
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Old 12-05-2019, 02:41 AM   #14
siickwrx
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Also does anyone think it could be the way I bolted it up? If I were to torque the downpipe to midpipe first, would it eliminate the gap? I'll try that next but I want to see if anyone fixed a leak that way.
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Old 12-05-2019, 02:13 PM   #15
MortonCharbo
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Quote:
Originally Posted by siickwrx View Post
I actually have that adapter. Does the cobb catback have a 3" flange or 2.5"?
When I had my Cobb catback, 2.5, it used the stock donut gasket.

As for torque sequence, start at the front and work your way back. Dp to midpipe first. Then midpipe to axle back. That should minimize possibilities for leaks. It should also make it apparent if you need different length hangers in different spots to get everything lined up right.
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Old Yesterday, 02:39 AM   #16
siickwrx
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Quote:
Originally Posted by MortonCharbo View Post
When I had my Cobb catback, 2.5, it used the stock donut gasket.

As for torque sequence, start at the front and work your way back. Dp to midpipe first. Then midpipe to axle back. That should minimize possibilities for leaks. It should also make it apparent if you need different length hangers in different spots to get everything lined up right.
Thanks for the input, i'll try torquing in that sequence. I would much rather move my exhaust leak to the axle back to save my lungs lol
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