For reference:
Originally Posted by kt883
Big thanks to Van462 for putting this DIY together. I tackled the job this mother’s day weekend despite not having any friends free to help out. I couldn’t wait and it seemed that every weekend was either raining, I was working or had something else that wouldn’t work so just said screw it and began. This was definitely the biggest job I have ever done with mk4 rad swap being my previous biggest job completed. It was intimidating but this thread and comments were all extremely helpful and encouraging.
I used a 15mm ratcheting flex head wrench for the cat bolts which worked wonders for all three once broken loose (used a TON of liquid wrench and Pb blaster). For the fourth bolt I could not figure out how to get that series of extensions from the bottom of car and was discouraged but I read the rest of the comments and saw mention of a 10” extension with a 15mm deep socket. Though it’s difficult to get it on the nut as you’re doing so blindly with limited hand access, I did get it after about 15 mins of screwing with it with the help of my jack handle as a breaker bar. Getting it back on is even harder but it helps to tape the nut into the socket so it doesn’t fall out. I used my phone video camera with flash on steady to peer at the screen tucked down there so I could sort of barely see what I was doing which helped out big time but is so awkward to manage by yourself. Pulling the Cat out the top is VERY frustrating!! I was ready to lose it when I violently wiggled it and it finally came out the top of the engine bay. You have to get the angle just right!
The wastegate bolts are pain to get at with the allen key but once broken loose you can undo and reinstall with your fingers. I elected to use my old WG actuator and shorten it as I noticed the actuator itself was strong but the door was loose by about 1/4” so shortening rod by ¼” as directed worked like a charm. Make sure you leave enough slack from the bracket as I cut too short and had to clamp it with pliers after extending rod with compressor to clear bracket enough to thread it.
I broke off all three downpipe bolts and could not drill through them with my drill and HSS drill bits (barely made a dent with my weight on drill!) so I took the exhaust off to get drilled by a machinist buddy. The exhaust clamp at the other end was completely seized with no hope so I just broke off those bolts too and it just fell apart. Had to hammer the socket on as they were so badly corroded around the area it didn’t allow it to just slip on. I’m currently running car with nothing after cat so its pretty loud lol my neighbors hate me. I finished at 11:30pm and anxiously started it up to test it but it was too loud to even leave my driveway at that time.
Next day I took it for a ride and SUCCESS! Car is boosting at 16 PSI peak (from 7psi!) and pulls hard. Exhaust roars at full throttle which is kind of nice, but draws a lot of attention. I will have some fun with it for a week or two then bolt it back up. Thanks again everyone who chimed in with advice.
Your best friend during this job
What I used to get that last hidden cat bolt
The tool in position
Comparison of old clogged cat with replacement - Likely clogged from stuck injector
I used a 15mm ratcheting flex head wrench for the cat bolts which worked wonders for all three once broken loose (used a TON of liquid wrench and Pb blaster). For the fourth bolt I could not figure out how to get that series of extensions from the bottom of car and was discouraged but I read the rest of the comments and saw mention of a 10” extension with a 15mm deep socket. Though it’s difficult to get it on the nut as you’re doing so blindly with limited hand access, I did get it after about 15 mins of screwing with it with the help of my jack handle as a breaker bar. Getting it back on is even harder but it helps to tape the nut into the socket so it doesn’t fall out. I used my phone video camera with flash on steady to peer at the screen tucked down there so I could sort of barely see what I was doing which helped out big time but is so awkward to manage by yourself. Pulling the Cat out the top is VERY frustrating!! I was ready to lose it when I violently wiggled it and it finally came out the top of the engine bay. You have to get the angle just right!
The wastegate bolts are pain to get at with the allen key but once broken loose you can undo and reinstall with your fingers. I elected to use my old WG actuator and shorten it as I noticed the actuator itself was strong but the door was loose by about 1/4” so shortening rod by ¼” as directed worked like a charm. Make sure you leave enough slack from the bracket as I cut too short and had to clamp it with pliers after extending rod with compressor to clear bracket enough to thread it.
I broke off all three downpipe bolts and could not drill through them with my drill and HSS drill bits (barely made a dent with my weight on drill!) so I took the exhaust off to get drilled by a machinist buddy. The exhaust clamp at the other end was completely seized with no hope so I just broke off those bolts too and it just fell apart. Had to hammer the socket on as they were so badly corroded around the area it didn’t allow it to just slip on. I’m currently running car with nothing after cat so its pretty loud lol my neighbors hate me. I finished at 11:30pm and anxiously started it up to test it but it was too loud to even leave my driveway at that time.
Next day I took it for a ride and SUCCESS! Car is boosting at 16 PSI peak (from 7psi!) and pulls hard. Exhaust roars at full throttle which is kind of nice, but draws a lot of attention. I will have some fun with it for a week or two then bolt it back up. Thanks again everyone who chimed in with advice.
Your best friend during this job
What I used to get that last hidden cat bolt
The tool in position
Comparison of old clogged cat with replacement - Likely clogged from stuck injector
Reply With Quote
Bookmarks