Exhaust leak while in drive and WOT?

[SJAndrew]

I have what sounds EXACTLY like an exhaust leak. I can only hear it when under heavy or WOT and while driving. I can't reproduce it in neutral and WOT (until it splieks the rev limiter). It sounds like my old lawnmower when the muffler rusted off. It's a loud ticking noise.

I've inspected my exhaust system, manifolds, cat, muffler etc, and can't find nothing. I live in a very ariod environment so I have no rust at all.

I've also checked suspension, bearings etc. I'm as suare as I can' that it's exhaust.

It's a little louder from the driver side and also sounds like it's coming from the engine area.

Any ideas?

[mechguy]

What exhaust configuration do you have?

Edit: Notice you have manifolds so I assume stock.

[SJAndrew]

All stock (exhaust), 138k miles.

During the exhaust notes, the car performs perfectly. I pulled all of the plugs and all are pristine (plus I wanted to make sure one wasn't loose and causing the exhaust leaks). No chugging, no misfires, nothing else weird.

[dsmuts]

gasket from the dp to catback?

[SJAndrew]

There is no gasket issue. It's perfect (between the two flanges).

There is a flex joint between the DP to cat (past the flange, cat side) - it seems to be in tact, but I can't tell.

I'm wondering if excessive engine movement (stock upper mounts, very slightly rotted) cause the engine to twist under load and open the flex joint.

I can't see any damage with the joint - but I also can't see if when the engine has twisted (like under load).

I'm stumped - I may record and post as it's very annoying.

[dsmuts]

seafoam it and you'll be able to see where it's leaking at

[Iceman6669]

seafoam it and you'll be able to see where it's leaking at

Thats the TRUTH!!! I just seafoamed mine and it smoked like a jonesing crackhead.

[SJAndrew]

The seafoam idea was a stroke of genius.

My car billows smoke from the rear exhaust manifold (of course).

My plan is to pull it this weekend and see what I can see. I can always weld it back depending on what I find. I can't tell if it's from the mani itself, a gasket or what.

Any advise/infpo regarding pulling the back manifold? How long does it take etc?

It looks like something I can knock out over the weekend.

[BillBoost37]

Easiest way to pull the manifold is to remove the downpipe and wiggle it out the tunnel hole from below. If needed lower the subframe 2-3 inches at tha back to give you more room.

Beyond that.. a deep ball pivot snap on socket with a long extension and air tools is the easiest way I've found to pull the bolts.

[SJAndrew]

I don't have air tools (worth a crap).

I assume you access the mani bolts from above, or is it easier from below after you remove the DP (with a real long extension)?

I'm going to put it on stands tonight and check it with Seafoam again. All I could confirm last night was that it was coming from the area between the back of the engine and firewall.

I don't know for sure that it's a cracked mani - it might be something with the DP or....? I'm going to look at it from underneath and see if I can better pinpoint the source.

[SJAndrew]

Okay, I found the problem...

I'm not sure what it's called, but it's leaking out of the top of the catalytic converter, where it connects with the back of the manifold.

There is a flange-to-flange connection gaskested with a standard exhaust gasket, then a flex connection welded on the cat. This flex connection is leaking.

It looks like I need a new cat, or a new connection welded on at least.

Is this a common failure point??

[dsmuts]

you can get a new flex welded in last time i did that i got new exhaust from the cat back and all together it was $150

[SJAndrew]

The car has almost 140k miles on it - I just bought a new cat.

The flex connection had completely failed. I will post a pic later - the interior portion (a sleeve) has come off.