Well, for a while i had noticed my car has been dogging out on a start, and about 2 weeks ago the secondary pipe snapped off the manifold. I figured it was a clogged cat because I have had that happen on my old sentra. Well, i couldn't get the cat off, so i replaced the manifold and secondary with a PS header. Tonite i was driving along, still dogging at starts, and all of the sudden i hear the exhaust cutting in and out. Then my RPM's went down to about 0 and the check engine light went on right before it stalled. It will not start now. When i try to start it, there is a loud banging noise at the cat, like it is jumping around. It just cranks but wont turn over now. Does this sound like a clogged cat? Keep in mind the engine didn't knock and there is oil in it. I am going to order a new cat tonite, so hopefully this will solve the problem, once i get it home that is.

i dropped the far end of the secondary pipe and the car started right up. I am 99% sure it is my cat now. Any one have some hints on gutting out the cat, *** i cannot afford a new cat at this time.

take the but end of a hammer handle and bang away at the inside

Will our car's run fine with a gutted cat? I think i might do this to avoid the cost of replacing it.

Thanks,
Mike

i will let you know if i can ever get my cat off. The bolts are on so tight.

Originally posted by Da91NX
i dropped the far end of the secondary pipe and the car started right up. I am 99% sure it is my cat now. Any one have some hints on gutting out the cat, *** i cannot afford a new cat at this time.

You can get a brand new, hi-flo cat for around $60 from Summit Racing (Catco). A muffler shop might charge you $30 - $40 to weld it in place. Not too expensive at all.

Steve

unfortunatly i need to fix it quicker so i can drive it. i8 cant be waiting for a week to get the cat. I mean i will probably order one, but i need to get my car on the road as quickly as possible. Does anyone have any hints on how to get those rusty old bolts off of the exhaust? I have tried PB blaster, liquid wrench, and WD-40. Anyone? And how come the bolts are smaller than a 17mm but yet larger than a 16mm. Even a 5/8 is too small but yet a 11/16 is too big.

Cut them out. New bolts should cost less than a dollar at your local hardware store.
I think rust causes them to become odd sized. I've had several bolts that were an odd size on my car, they all had rust on the heads.

Unfortunatly they cannot be cut, they are just stud with the 6 sided heads. The flanges must be threaded. I have soaked and soaked these 2 bolts and cant free em up.

Get a pair of large vise-grips. Make sure the teeth on are going in the correct direction when loosening them, otherwise, it will just spin on the head. Buy four nut/bolt combos as a replacement. When gutting the cat, remove the steel meshing as well as the honey comb material. Expect your exhaust to be a bit louder w/gutted cat.

Also, try a local salvage yard. Most won't sell them but plead your case, they may have pity on you. All se-r's, nissan pick-ups (later models), and of course G20's have the same cat.