Hero

so i have a small exhaust leak. no big deal. i've been through a couple exhausts and the gasket is probably several years old anyways.

I went to honda for a new oem exhaust gasket ( cat back ) and was giving an O ring type gasket. I guess this is the oem part? i don't remember, but i've always had the "house" style or A-framed type of perforated gasket on there. maybe this is what came with the first aftermarket exhaust?

anyways, i assume the O ring works just fine, but is one style preferred over the other? I was just really confused when the parts guy handed me an O ring gasket.

I just want the leak to go away, so whatever seals the best. ( or maybe they are basically the same exact thing? )

pemex70

That o ring gasket sits in a recessed ring on the exhaust flange. The hard part is prying the old one out. With the proper tools it shouldn't be bad.
The old one is most likely flat already.

You're using an OEM exhaust now?

The triangle gasket mates two flat surfaces. Which most, if not all, aftermarket use.

CoolGuy094

There is a flat gasket between the engine block and header. There is a donut ring gasket between the header and the cat. There is a flat triangle gasket between the cat and the exhaust. Where is your leak coming from?

pemex70

The first 2 are correct.
There is no triangle gasket between the cat and exhaust, it's a metallic o ring like mentioned.
...unless this is AP1 specific. I've owned a '05 and '07 and both had o ring gaskets.

xviper

You are correct. Only aftermarket cat back systems utilized the "triangular" flat gasket. The stock one is a metallic ring, or more precisely, a cylinder.
Here is the aftermarket triangular gasket:
[media]https://www.dropbox.com/s/f0flhaq1s4crcqh/Fujit0007.JPG[/media]

If you have the OEM cat back, it should have the ring (cylinder) grafted onto the front pipe that bolts to the rear of the cat. If it's still there, you shouldn't need to replace it. It doesn't go bad. Your leak is probably somewhere else or you don't have the 3 bolts cinched down evenly.

CoolGuy094

Well blimey! My mistake guys... I guess I've had too many aftermarket cats and exhausts to remember correctly!

pemex70

S2Ki

Hero

Thanks for the info guys. so here's the deal...had a couple aftermarket exhausts matched up with a berk HFC. Been using the triangle like gasket for several years.

but i switched back to an oem ap2 exhaust and the berk hfc ( on an ap1 if it matters ). Wonder which gasket i should use then? Berk is just down the street from me also so i could go get an aftermarket gasket with little trouble also. Thoughts?

I remember when i put the ap2 exhaust on, i reused the triangle gasket and it was in pretty bad shape. so i am assuming that's where the leak is coming from...but i also did swap my ricks header back to oem as well, so there could be a leak coming from there too.

Honestly, i hear it, just haven't checked yet. I was next to Honda on saturday so just decided to pick up the part and keep the receipt. I'll get under the car this weekend and see where the leak is. I'll also try just checking the 3 bolts as well before anything...maybe it's as simple as that.

xviper

Now that you've given all the details (as you should have done right from the beginning), it's possible to make further comment. The HFC was designed to be a direct replacement for the stock cat. Thus, it was designed to be mated with the stock header and stock cat-back. Any aftermarket header is also designed to mate with the stock cat. The difference comes when you put on an aftermarket cat-back. Those were designed to use the triangular gasket as the metal ring is not easily transferable from the stock exhaust to the aftermarket one, so aftermarket manufacturers do not design them to accommodate the metal ring.
If you put the stock cat-back back onto the car, it will still have the original ring. If you still have remnants of the triangular gasket on the back of the cat, then you are attempting to use 2 gaskets where only one is needed. The triangular gasket makes for just enough of a gap between the rear of the cat and the front of the stock cat-back, that the metal ring won't seat properly. You also say that the triangular gasket is not in good shape. Scrape off all bits and pieces of the old triangular gasket, sand it down smooth and then complete to join.
Now that you've told us that you had an aftermarket header and now have gone back to the stock header but still retain the HFC, there is no guarantee that the metal donut gasket will provide a good seal. The ridges formed in the old donut won't match up with new combination. Also, those 2 spring bolts should NOT be done up completely tight. That join must have the ability to shift when the engine and exhaust system rocks.

Hero

Understood.

I'll get under the car and figure it out this weekend now that i understand everything a little better. Might need to replace the header/cat gasket then.

Thanks xviper and everyone else.