Aftermarket Catalytic Converter Install

After reading about the spike in Catalytic converter thefts all over the country I decided to pre-emptively switch out the OEM Cat for an aftermarket cat. Thanks to TMR-JWAP who initially suggested this and who also gave me advice on the install. Obviously this only applies to States that allow the use of aftermarket cats.

I think this is the best way to deter theft and if a thief is dumb enough to steal the aftermarket cat (CAT would probably fetch less than $20 scrap), it's cheap enough to replace with another one. Did I mention that this replacement will net you at least $1000!

I ordered this catalytic converter model on Ebay (cost me right around $120 with tax, 10% off offer appears to be expiring today). Apparently, it's the identical model to this Autosaver88 model on Amazon.

So after watching a ton of Youtube videos and reading comments and reviews, below are the steps I followed to remove the oem cat and install the aftermarket replacement. Hopefully someone will find this useful.

1: Jack up the entire car. I used homemade car ramps that are only 4.5" high - this made things extremely difficult as virtually no space to maneuver. If you have access to a lift, it would be exponentially easier. If I could redo, I'd make sure to get the car up higher with some decent lifts.

2: Loosen the spring bolts at the exhaust manifold (I used a 9/16" socket and at least a 10" extension). I did this first just to make sure I was able to get them loose before proceeding. I ended up using a breaker bar for one of the bolts. After breaking them loose, I still left them screwed in all the way. Pic A shows the location of the spring bolts.

3: Remove the O2 sensor. A 7/8" wrench will work but I just used a large adjustable wrench (required a good bit of force). I counted the rotations to remove (3 full rotations for me) so I could pre-twist the wire when re-installing the sensor in the replacement cat. I put the hanging O2 sensor in a plastic bag (to avoid decontamination) and zip tied it closed, then tucked it away on a segment of the underbody shield. Pic B shows the bagged O2 Sensor.

4: I marked the pipe 5cm from the resonator side (see pic C) and cut it with my sawzall. I used a cheapo 6" Harbor Freight (Warrior) 14 TPI "thick metal" blade. Maneuvering the sawzall in such a small space was extremely difficult but after about 10 minutes I managed to cut through. I would not recommend the Warrior blade. For a redo, I would buy a better metal cutting blade. This Milwaukee Torch blade was recommended in one of the videos - I would think 18TPI would be ideal.

5: I returned to the spring bolt side and removed them, thereby releasing the cat.

6: Prep the remaining pipe on the resonator end. I deburred the cut side of the pipe with a file and sandpaper so it was smooth to ease install of the slip-on replacement. I then applied Ultra Copper gasket maker to the pipe end (This product was highly recommended, especially for exhaust applications). Pic D shows the remaining pipe with gasket maker applied.

7: I temporarily removed the oem donut gasket which was still in place in the exhaust manifold. I then maneuvered the replacement cat so the oxygen sensor hole was roughly in the same alignment as previous. I then pushed the resonator back while at the same time maneuvering the replacement cat so that I managed to slip it over the remnant pipe segment extending from the resonator. Since the resonator side is supported by rubber hangers, it is possible to push it back about an inch, but it still required a fair amount of force. Panic then set in as the overlap was only about half an inch and the side that bolts into the manifold was misaligned by about 20 degrees, but the new cat seemed locked in that position. I wasn't sure if the Copper RTV was my issue or if it was just a lack of leverage due to the limited space. Thankfully after about 30 minutes I managed to rotate and push the replacement further over the resonator pipe end.

In retrospect, I think I would first take the resonator end off the rubber hangers (see pic C). For ease of removal people have recommended the use of soapy water on the rubber or WD-40. I think the soapy water is a safer option as not sure if the WD-40 degrades the rubber. Freeing the resonator section from these hangers should allow one to push the resonator side further back, likely making it easier to slip over the new cat.

8: Replace the original donut gasket (as long as it's in fairly good shape). A few reviews claimed that the new gasket that comes with the aftermarket cat caused issues which were resolved by using the original. I also used the original spring bolts (after cleaning) with some anti-seize. Note: You must make sure that the collar on each bolt passes through the flange holes in the replacement cat (see pic E). Those collars will butt up against the exhaust manifold. After I visually confirmed this, I torqued them to 32ft-lbs.

9: Install the exhaust clamp on the overlapping pipe. I did not use the clamp that came with the cat. Instead I used TMR-JWAP's recommended Nickson 1 3/4" Heavy Duty Exhaust clamp which seemed plenty sturdy to me. I used a 9/16" deep socket and torqued the bolts to 32ft lbs.

10: Remove the temporary cover-bolt that comes screwed into the O2 Sensor hole of the aftermarket cat (8mm Hex). I then applied a small amount of anti-seize to the O2 sensor threads (I made sure to use the copper "sensor safe" Versachem variety). I then re-installed the O2 sensor by first pre-twisting the wire (for me by 3 full rotations) and then tightening with a an adjustable wrench (apparently 7/8" works too).

11: As an extra deterrent I wrote "Aftermarket Cat" and "NOT OEM" on several sections of the replacement cat. I used a Sharpie Industrial Marker which is rated to 500 deg F... so maybe it will stay on there for a while.

I let the car sit overnight so that the Ultra Copper gasket maker cured. She started right up this morning and sounded identical to before the replacement. As far as passing emissions is concerned, I'll only know this time next year as I made sure to get my emission test completed before the replacement.

 

I should add that if I had someone to help me, I likely would have removed the whole exhaust assembly and performed the cutting and cat replacement away from the car.

 

Yep, the under-car replacement is really not that difficult given a bit more space.