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Thursday, February 29, 2024

Doug's Domain

Doug Vetter, ATP/CFI

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Thursday, January 8, 2009

Catalytic Converter Replacement

While on my way to my uncle's house for Christmas dinner the CEL illuminated again. It didn't take long to realize a) what caused it, and b) that I would be spending a considerable sum of money in the very near future. Of course, the car didn't skip a beat and I completed the trip without incident.

The following day was a company holiday so I used the spare time to order the parts necessary for the repair. First on the agenda was a visit the dealer's parts department to order a new mid-section. At a discounted price of $1850 including tax the part wasn't exactly a bargain but the dealer made the purchase relatively painless by giving me Tischer's price -- a full 20% off the list. After briefly watching my technician trying to repair one of those stupidly complex panoramic sunroofs from an X5 I hopped in the car to do a few errands before arriving home to do a little parts surfing.

What parts, you ask? Whenever the exhaust is dismantled BMW recommends all new assembly hardware including special self-locking copper alloy nuts used to attach the midsection to the headers, header flange gaskets, and sealing rings that help bridge the gap between the mid-section and muffler section. In addition, common practice is to install new O2 sensors with new cats, but since I already replaced the pre-cat sensors a couple years ago I only had to grab two sensors to replace the post cat units.

(Image: Closeup of new catalytic converter installed on E36)While looking at my maintenance schedule worksheet I realized that the exhaust mounts were about 10K miles short of their 90K replacement interval. Since I was not interested in dragging two grand worth of exhaust on the ground I ordered two new rubber mounting rings as well as two new exhaust hangers and related hardware.

And just before I clicked the "Checkout" button I remembered that several months ago while I was under the car I noticed the black plastic raceway used to protect the post-cat O2 sensor wires had started to sag. I figured this was due to a failure of the raceway's integral mounting clips and decided that the $10 replacement cost for the raceway and cover was well within reason.

When it came to the installation I broke with tradition and decided to have my technician do the work, primarily to get the full two year parts and labor warranty. Sure, I could have screwed around in my bitterly-cold garage for the better part of an afternoon but for the two hours the dealer quoted to do this job it just wasn't worth it to me. So I arrived at the dealer this morning and checked in with my technician to let him know about the big bag o' parts in the car before jetting off in the loaner to get to work on time. I picked the car up in the evening and after a 15 minute drive home I got out and walked around the car with the engine idling. The first thing I noticed was that the occasional, very faint rattling noise coming from the cat heat shield was no more. The second thing I noticed quite by accident as I examined the muffler is that the exhaust actually smelled like, well, nothing. It was very dry and sooty, but did not smell like the exhaust output of the vehicle prior to the repair. Apparently these cats actually do something. :-)

Now for the fun part -- the cost analysis. Total of incidentals from Tischer was $456 including shipping and their discounts resulted in a $150 savings over list price. The cat normally retails for $2100, so including shipping I managed to save approximately $250 on that part by walking up to the parts desk and ordering it ahead of time. Had I simply walked in off the street and asked the service advisor to replace the cats I would have paid full list for that part. Installation labor was two hours at $120/hr plus SST, or $256. This brings the total for this repair to $2562.

Who says owning old BMWs ain't fun?

Mileage: 171000, Parts: $2306, Parts Saved: $400, Labor: $256