When I got my Rx7 it had about a million leaks up front in the exhaust. It has a Bosal rear system in very good shape but the front part of the exhaust had been repaired a few times and was semi hacked. So I bought a new stainless, 2 cat downpipe and installed it tonight. It came with gaskets and fits well. However, to my dismay, when I started the car I can hear I still have a big exhaust leak up front under the engine area somewhere. I can't imagine its coming from the manifold to downpipe seal, that is gasketed, extremely clean of old gasket residue, and the new flange is flat. The only thing I can imagine is the leak is even further forward - cracked manifold or manifold to engine seal. Is this common or possible?

Here's what I have on the car as of tonight.

 

its possible.

 

Could the sound be coming from the split air pipe (doubtful)? Anyways, seems you've pretty much narrowed it down to one of a couple things, cracked manifold and/or bad engine to manifold gasket. Both of which require you to remove the manifold, so get to it! I had the same thing happen to me with my 1st gen, replaced the gaskets and started only to find out that it still sounds like ****!

GL.

 

Also, make sure that the flange on your manifold, where you are bolting up to your new stainless system, is free of rust, etc. The flatter and debris free the flange is, the better chance you have of sealing it up with the gasket.

BTW... while you are under there with the camera, start it up, and find where the leak is specifically.

 

the manifold flange was beautiful and in perfect condition, it had been perfectly preserved by the old gasket and I cleaned it very well.

Getting under running cars on jackstands makes me nervous, the camera is a good idea

Steve

 

Neutral, and have someone rev the engine ssssslllllllloooooooowwwwwwlllllllyyyyyyyy.

Just being under these cars, while on jackstands, without the car running, makes me nervous. Not a lot of room to squeeze out, if something ever did happen.

Just make sure that the car is stable before going under. I usually grab hold of the fender, and wiggle the car back and forth, to make sure it is solid.

 

seem like you guys dont trust yourself's..try replacing the exhaust mani. they come at a dime a dozen anyway. although i have to admit that i've never heard of those thing's ever cracking. maybe a possible vaccume leak? is it a light whistling sound?

:AA:

 

It's an exhaust leak, no doubt about it. It's pretty loud.

 

oh ok..in that case replace the ex. manifold..im sure that will take care of it..

:AA:

 

usually the down pipe has a bung for an o2 sensor and i dont see a wire in the pick for a sensor is there a bung? if so does it have an 02 sensor or a cap?

 

the n/a manifolds rarely crack, in fact i have yet to see one cracked, that is a T2 issue not an n/a one. you probably have a nut or 2 that have backed off or possibly broken at the manifold itself to the engine.

 

There is no o2 sensor in this gen downpipe, it is in the manifold itself and yes it's there.

 

I was once given advice about how to torque exhaust bolts/nuts, to make sure they are tight enough. You have to star torque them. Basically, you torque them until you see stars.

Usually works for me.

 

^LOL. I am going to get a long piece of heater hose and put the car up on jack stands and use the heater hose as a stethoscope to feel around and listen where the leak is coming from. The flanges are all gasketed, clean and tight, so I hope the actual leak is at an easy to repair point upstream. I have a tube of permatex ultra copper and a welder so I should be able to seal anything

 

I found the problem, the aftermarket exhaust had very wide slots on the head pipe flange, so you could inadvertently slide it about 1/4" to either side. I had tightened the head pipe flange with it accidentally shifted over enough that the gasket was not seating. I like easy fixes

Steve

 

Kinda curious which CAT did u get ?

I got the Mangaflow single Main Cat only. Its pretty loud, Im just wondering will the 2 CAT setup lower the sound more.

 

It's an Eastern Catalytic Converter brand (US Made in pennsylvania) T409 stainless 2 cat system. It is very quiet, like stock. With a Bosal replacement rear exhaust this is a quiet car. I didn't use the Magnaflow 1 cat system because I wanted this car to be as clean running as possible.

 

Do you have a link for it ? like where you got it ? (assume you got it online)

Cuz I might have to dump this Mangaflow cat. I mean it does a pretty good job to pass emission with flying colors, but the startup emission is pretty bad, huge cloud of smoke and its pretty loud (for my taste)

 

It's from Rockauto.com and it's Eastern brand, I don't have the part # on hand but you can look it up on there

 

Thx