Jeremiah Harbach

This past weekend I was removing the passenger side catalytic converter to create extra space for replacing my water pump.

I broke two of the 3 bolts.

I saw this thread where OP said he "moderately tapped" out the broken bolt (back in 2011). Much time has passed since then, however, and the deteriorated condition of my bolts were well past the "moderate tapping" stage.

This is what I did to fix the issue.

Disclaimer, this is a hobby for me. I have SOME tools but not ALL OF THE TOOLS and this solution worked for me but it doesn't mean it's the best way to do it. I figured that someone in the future will be in a similar situation and find this thread useful.

1. The first step is to remove the broken bolt.

The bolt is actually a press-fit stud. Here is an example of one from NAPA auto parts.


Catalytic converter to exhaust header press-fit bolt (this one is for a Jeep)


Here is the one I removed:


catalytic converter press-fit stud (removed)

I did the following to remove the press-fit stud/bolt
1. Spray both sides of the bolt with Liquid Wrench penetrating oil
2. Put an 18mm socket over the head of the bolt
3. Put it in a vise
4. Tighten the vise to press the bolt out. It required all of my bodyweight tightening the vise to get the bolt to come loose.


The stud in this picture is intact but this is the method I used to extract the broken ones


This is the press-fit hole "threading". It's very effective at keeping a bolt in place - especially when the bolt is over 15 years old!

2. Come up with a replacement solution.
I called my Porsche dealer and they didn't have the bolt. The tech told me they typically drill those out and replace with a standard bolt.

I spoke with a former mechanic at a local auto parts store and he told me he used to replace with typical flange bolts which he said work just fine.

I bought an 8mm (1.25 pitch) 30mm bolt (grade 10.9), a lock washer, and a stainless nut and plan to thoroughly coat them in anti-seize before reassembling.


8mm - 1.25 thread pitch - 30mm flange bolt - grade 10.9 - from Ace Hardware

As for replacing with the original press-fit bolt:

I guess it's not uncommon to use these press-fit bolts on exhaust parts. Half of the problem is finding someone who knows what you're talking about. I went to 5 or more different hardware/automotive stores and only 1 of the probably 10 or so people I talked to even knew what the bolt was but he told me they didn't have it until I showed him a picture of it from their website (it was for an SAE bolt, not the metric one, though).

The replacement bolt is out there (somewhere) but I gave up and just went with the flanged bolts I mentioned above. I'm hoping it will do the trick.

Hope this helps someone else in this situation.

DesmoSD

Awesome, nice write up. Nothing ruins the day then a broken stud.

Rhern213

Had the same issues a few weeks ago installing a center pipe, took me almost a week to drill them out little by little, what a nightmare.

Goose 993

Guess I got lucky with my center pipe install. Just needed some PB B'laster and a breaker bar on the inner flange nuts.