AWSX1686 New Reader
April 21, 2014 9:57 p.m.

Hi, me and my dad are putting a new Catalytic Converter in our 1987 BMW 535 IS. We’ve managed to get the rear of the Catalytic Converter disconnected from the exhaust, but where it bolts onto the engine is giving us a little trouble.

Any tips on getting it unbolted?

GSmith Reader
April 21, 2014 11:20 p.m.

Any help would be greatly appreciated!

We are trying to remove the middle section of the exhaust from the exhaust headers, which are surprisingly short on this car! We don't have air tools - just hand tools and a lot of extensions.

I'm pretty sure these bolts have been in place since the factory installed them in 1986 or 87 depending on the build month. They aren't budging so far.

Apexcarver PowerDork
April 22, 2014 8:25 a.m.

In a few cases I have ended up giving up and using a sawzall. That is after using an impact gun to completely strip something, or in a few cases, to just break the hardware.

Some of that hardware is just not gonna come apart.

Advan046 HalfDork
April 25, 2014 2:32 p.m.

It sounds like you don't have room to cut that section off near the header. I think you should post a photo of the area to help.

Options may be:

  • Remove the exhaust manifold and deal with it off the car. Or replace with new manifolds.
  • Hack at it with a rotary tool to cut the head of the bolt/nut off.
  • Cut as much of the exhaust as you can if that helps get you a better angle to torque the bolts.
  • Blast the nut with heat or manifold with heat from a strong torch then see if it comes out. (I have only had success with heat once. Not my favorite)
  • PB Blaster
AWSX1686 New Reader
April 25, 2014 4:05 p.m.

We were able to get it off with patience and a couple soaks of PB Blaster over a couple days. Same thing worked for the oxygen sensor, though we had to use the force of a sledge hammer and a 6 point closed end wrench...

GSmith Reader
April 25, 2014 6:47 p.m.

Penetrating oil (FWIW, I was soaking it ~3x/day even if you didn't see me doing that), patience, and a breaker bar...

PB Blaster is pretty impressive.

for the header nuts, that was a 1/2 bar and some long extensions... but some hammering to tighten, then loosen, then tighten, then loosen did eventually break things loose.

For the O2 sensor, I damaged the flats trying with a Harbor Freight O2 sensor socket (it spread open and the sensor stayed right where it was). More PB Blaster, more time, and a 6-point Craftsman wrench (plus the sledgehammer described above) got it done.

Thanks for the advice everyone!!

You'll need to log in to post.

Also on Grassroots Motorsports

Autocross: It's a Jeep Thing

12 hours ago in Articles

What’s a yellow Jeep doing on an autocross course?

GRM Live on Wednesday, June 28: The Science Behind Fasteners

15 hours ago in News

They hold all of your work together, but do you know when to use each type of fastener?

Tech Tips: 2005-'14 Ford Mustang GT

15 hours ago in Articles

Want to learn some speed tricks for the S197 Ford Mustang GT? We brought in an expert.

Removing Clear Bra From Project Rallycross Focus

16 hours ago in Project Cars

Our latest to-do item was motivated by self-respect rather than speed.

2017 Ram 1500 Night Edition Crew Cab

16 hours ago in New Car Reviews

Half-ton trucks are just getting bigger and bigger, aren't they. This Ram 150, dubbed "Night Edition," is really an optioned-out ...

Get Your Subscription Combo Deals!

18 hours ago in News

Get both our magazines for the price of one!

Action Cam Guide

1 day ago in Articles

Capture your on-track memories with today’s latest and greatest

Reader's Ride of the Week: Troyer Modified Hillclimber

1 day ago in News

It's a circle track car that's been convinced to turn left and right, and go up hills.

You Need This: Track-Ready 1991 Mazda Miata for $5500

1 day ago in News

What’s better than a Miata? How about a Miata that’s ready for the track?

MX-5 Cup Racing: Live on Your Screen This Friday and Saturday

4 days ago in News

Catch all the action of the Global MX-5 Cup race at Road America live this weekend.

How to Run Compressed Air at Home

4 days ago in Articles

A guide for installing an air compressor and air tools in your home garage.

2017 Volkswagen Golf SportWagen TSI 4Motion

4 days ago in New Car Reviews

Say hello to the Volkswagen Golf SportWagen TSI S with 4Motion. It comes with a turbocharged 1.8-liter engine that is ...

OUR SPONSORS

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More
NTBggSjyIZwmYVqrS6c2YK8RgHQUM2Bo