Catalytic converter bolts/studs

[dcporsche99]

Nice write up Dana! Sorry for slow response. Here's a pic of the top bolt on the passenger side that I was talking about. Note the three washers on the cat side. Also note (not related to the pic), make sure you tighten the nut on the bung of the header. The after-market header that I bought was made for either the Boxster or Boxster-S, so it had a bung for installing O2 sensor (for Boxster-S). I figured it was tight from factory so I didn't bother; well it rattled OFF during my morning commute. I didn't have an extra plug so I was in a bind. No local source had it and overnight delivery from Pelican was going to be $50. Since it was made for an O2 sensor, I simply installed an old O2 sensor I had from previous R&R. It sealed fine and I am driving her around until the plug comes.

The R&R was definitely worth it. The car sounds soooo much better. The exhaust no longer sounds like an indistinguishable loud vacuum cleaner but has more tone to it. The car also accelerates better. The slight hesitation in 2nd gear is now completely gone. This will keep me happy for at least 2 weeks :D

Hey Hung,

No prob. Thanks!! Nice pic!

Definitely a bit of difference in sound.... and the ride has a bit more zip to it, huh?? :P

Glad it all worked out for you. Enjoy!

[Stefan]

Thanks for the discussion, folks. It sounds like we're all dealing with the same sort of issues. And it's very helpful to hear how others have solved them.

I have been procrastinating on finishing the header replacement on my car for several reasons.

On both sides I got the nuts off with considerable effort (torch, dremel, etc.) and on both sides the cat refused to separate from the header. The driver's side eventually separated after a bunch of driving with no nuts holding them together. After it separated I put on a single nut to hold it on until I'm ready to complete the job. However, I found that after less than a month the nut (which came with the aftermarket headers I got from eBay) is completely corroded.

So I will get better quality nuts and bolts to hold the headers before I will complete this job. There is no point in using cheap quality fasteners given the amount of time and money we have spent on the rest of the job.

I am also debating the merits of heat wrapping the headers before installing them. I am also considering having them ceramic coated.

I have been driving with no nuts holding the passenger side header to the cat and even after a couple of weeks it hasn't separated. It looks like I will have to use more brute force to get it off.

Thanks for the thoughtful DIY, Dana.

[dcporsche99]

Thanks for the discussion, folks. It sounds like we're all dealing with the same sort of issues. And it's very helpful to hear how others have solved them.

I have been procrastinating on finishing the header replacement on my car for several reasons.

On both sides I got the nuts off with considerable effort (torch, dremel, etc.) and on both sides the cat refused to separate from the header. The driver's side eventually separated after a bunch of driving with no nuts holding them together. After it separated I put on a single nut to hold it on until I'm ready to complete the job. However, I found that after less than a month the nut (which came with the aftermarket headers I got from eBay) is completely corroded.

So I will get better quality nuts and bolts to hold the headers before I will complete this job. There is no point in using cheap quality fasteners given the amount of time and money we have spent on the rest of the job.

I am also debating the merits of heat wrapping the headers before installing them. I am also considering having them ceramic coated.

I have been driving with no nuts holding the passenger side header to the cat and even after a couple of weeks it hasn't separated. It looks like I will have to use more brute force to get it off.

Thanks for the thoughtful DIY, Dana.

Hey Stefan,

You are welcome! Thanks for the props!!

Glad to hear you're almost done...+1 on high quality fasteners!

Not sure about heat wrapping the headers completely or ceramic coating them. From what I hear, they increase the amount of heat going to the cats that may cause premature cat failure(s). Unfortunately, I don't have any literature to substantiate this so, .....but I'm sure you'll do your homework on those options.... as you know I just wrapped selected areas on my passenger's side header as a matter of necessity.

Anyway, as for the "header to cat" issue...I'm impressed that it held up from the drive! :D As I mentioned in my PM to you, IMHO, I would give them a heavy dose of PB blaster...maybe it will help loosen some of the rust where they meet.

Keep us posted!! :)

-Dana

[Stefan]

Success!

(Continuing adventures...)

The last I posted, I had removed the nuts on the headers but was unable to separate the stock headers and cats. Since then...

I gave up on trying to separate the headers and cats on the car. So I removed the rear bumper, the cross braces, etc., and removed the entire exhaust system in one piece and brought it out to my back yard. You'd think that it would be easy to separate them from this point, but no.

I pulled, I twisted and they wouldn't budge. I tried hammering a screwdriver between them but as soon as I applied any torque, it broke.

I hammered in a 2' pry bar. I put all of my weight onto the pry bar. The pry bar bent as I pushed it but those two flanges were not separating. I hammered the pry bar in farther. I pried. I prayed. After considerable effort I finally managed to separate them. I was running out of time and even though I wanted to tackle the cat flange bolts, I had to put everything back together.

I got everything back together, started up the car and it definitely sounded better, more of an open (less choked) sound.

But with the car heated up the car was leaking some exhaust on both sides but only when on throttle.

Yesterday I replaced all of the header to cylinder head bolts and torqued them to the proper specs. No change in the exhaust leak.

So this morning I took an extra pair of cats I had lying around (yeah yeah, I know) intending to remove the studs (the original point of this thread). It was actually pretty easy. I removed the O2 sensors, heated the studs up with a torch, and hammered them out with a regular 14" metal hammer.

One interesting note is that I do not think that the studs were welded in. I think they were pressed in. I removed them intact and I see no signs of a weld. This means that theoretically they could be pressed out if you could get a very large set of pliers at the right angle.

Check it out:

I still have to put the cats into the car but the hard part is done.

Thanks everyone for posting your experiences. It helped a ton.