Changing Cat and Muffler

Warviking · 06-15-2005, 03:42 AM

I'm about to change the cat and muffler on my car and just want to make sure I have everything I need. Hate to get everything apart then realize I need something and have to order it and wait. I'm installing a GHL Sport cat and mb911 single in/single out muffler. So I believe I need 3 gaskets, 1 between muffler and cat, and 2 between cat and exchangers. I think I'm going to replace the 02 sensor now. I just passed 80k miles and I read somewhere it should be changed every 40k. I hate to spend the $200 on it if I don't need one, but I don't know when it was last changed. Changing it now a good idea? Since all the nuts and bolts are pretty rusty looking I was planning to get some stainless from the hardware store. Is that an ok plan? Any kind of special nuts or bolts I need? Well I think that's about it. Please give me any tips you might have as I want this to go smooth. Hate to be without the car.

fuelie600 · 06-15-2005, 04:40 AM

If the engine is running good, I would delay the O2 sensor until I had to do it. For $200, it would be worth the wait! (just MHO, I'm cheap.) It's not hard to change with the exhaust on the car later.

The stock bolts are M8x40. They are hard to find in stainless. Others have been using 5/16-18x1 1/2 in stainless with Silicon-bronze lock nuts. Not sure how hard it is to find the nuts.

You are good on the gaskets. The ones for the heat exchanger to cat are different from each other. one is round and one is oval.

Let us know how the mb911 muffler sounds. I'm getting ready to swap my cat for a euro pre-muff. I'm thinking I might need one of Ben's cans to go with it!

Good luck!

Groesbeck Hurricane · 06-15-2005, 05:03 AM

I went with the SS nuts and bolts and found that I scratchee the bolts on insertion. This caused the nuts to bind on the bolts and I ended up cutting them off. The ones that I did not damage were easy to take back off... Do a search on O2 sensors. If I am not mistaken you can make an inexpensive generic sensor work. The issue is finding the correct one for the hole.

Nine9six · Nine9six's Garage

I believe you have all thats needed to perform the task. Smart thinking on replacing the fasteners with SS. Do a search on "Turn6" I remember him posting a site for 02 sensors in the $40. range.

Thrasher · Thrasher's Garage

I bought a $45 "universal" 3 wire O2 sensor and cut off the old one, re-using the OE connector. The new one came with instructions, heatshrink and anti-seize. Google search for "911 02 sensor" will get you plenty of hits. Wayne should consider carrying these as an alternative to the $200 with OE connector, assuming he can be cost-competitive.

Very easy job, assuming you can remove the old one. Soak it with PB Blaster 24 hours before trying to remove.

edit: just remembered, I bought from www.oxygensensors.com - still $45

mb911 · mb911's Garage

warviking!

I have the muffler gaskets straps and hardware all in stainless here you just need the by pass gasket..

fastpat · 06-20-2005, 08:20 PM

Quote:

Originally posted by Warviking
I'm about to change the cat and muffler on my car and just want to make sure I have everything I need. Hate to get everything apart then realize I need something and have to order it and wait. I'm installing a GHL Sport cat and mb911 single in/single out muffler. So I believe I need 3 gaskets, 1 between muffler and cat, and 2 between cat and exchangers. I think I'm going to replace the 02 sensor now. I just passed 80k miles and I read somewhere it should be changed every 40k. I hate to spend the $200 on it if I don't need one, but I don't know when it was last changed. Changing it now a good idea? Since all the nuts and bolts are pretty rusty looking I was planning to get some stainless from the hardware store. Is that an ok plan? Any kind of special nuts or bolts I need? Well I think that's about it. Please give me any tips you might have as I want this to go smooth. Hate to be without the car.

Here's an article I did on the PCA Diablo Region forum about a week ago on replacing the catalytic converter with a euro-type premuffler. The project took me a few hours working alone. With the muffler swap, plan on an exta two hours or so, but it's really straight forward wrenching.

As someone mentioned, there are three gaskets, however, I reused mine since mine were undamaged and the car only has a bit over 25,000 miles on it. Also, don't tighten every thing down untill you get all of the bolts in their correct locations with nuts on finger tight. You'll need to move things around a bit to get all the holes to line up. A helper to lift one end of the muffler up into place might be a good idea.