Some notes on CP3 swap upgrade

N2BRK

Well-known member
Dec 31, 2009
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Just to throw this out for folks going down this road. I recently completed my swap to a 12mm Exergy.

If you aren't pulling the turbo, then you can have a problem pulling the passenger side upper Y-bridge bolt. I searched a bunch and people were making a lot of suggestions that really didn't work for me. I was tempted to just cut the damned thing and then replace the bolt with a smaller head... which is exactly what Josh (from here) suggested in an old post that I found! Saved my ass :) Thank you, Sir.

The next issue is replacing the o-rings on the y-bridge intake tube. GM thinks that they are spun from gold. I searched and read about orings from Napa that some people had success using, but some didn't. I found that Felpro and Mahle both make o-rings for this application... and they are cheap and readily available! Here's the info I've found:

Napa orings: some used 236 and some 237.
Felpro: 72946
Mahle: G31914
Autozone has Mahle and Napa has Felpro (both needed 1 day to get; plan ahead).
The orings are 3.25" x 3.5" x 1/8" thick
I cannot confirm this, but I was told that Felpro ES73020 is a kit with both o-rings.
I bought the Felpro from Napa and they hit me like $2/ea I think.

I had previously replaced the coolant hoses with the PPE silicone kit, so things mostly went back together without drama. But there are still several hoses that apparently are not in that kit... and some of mine leaked after reassembly! The two biggest problem leakers were the hoses that live on either side of the turbo. The driver's side was easy; I replaced with a short length of 3/8" silicone hose. The passenger side needed 1/2" and has a factory 90* bend to it. I was in a rush and couldn't get more silicone, so I went to Advance Auto and raided their supply of pre-bent coolant hoses. I found, cut, and used a Carquest Dayco A71685. It worked well and was about $11.

The last problem that I had was the very short bent return hose from the top of the CP3. She leaked after install. I had not planned for this, so it wound up being an after-the-fact replacement. GM holds this part VERY dear at about $50! Bastards. It's much much cheaper if you plan ahead and buy this hose over the interwebs! GM Hose 355 on the fiche. Part 1262578. Make sure that it looks right - the local dealer was trying to give me the wrong part and claimed it was the same part number on the fiche. I also got the factory clamp (number 30 on the fiche but I didn't write down the p/n, sorry) and it was a God send! That clamp comes opened wide with a little tab that you pull to let it spring shut. This let me simply remove the AC compressor and sneak the job from the side, instead of tearing back into the truck. I got that clamp on with some needle nose, and then popped the cap and the clamp was golden!

I think that's about it. I did thermostats since I had the cover off anyway and have 100k+ on mine. I also did a new green Gates belt, since it was convenient to do so.

Be sure to pressure test for coolant and boost leaks after you're done.

I hope that this helps someone :) :hug: LOL

Wally
 

OregonDMAX

NOT IN OREGON, NO DURAMAX
Apr 28, 2013
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Goodyear, AZ
Sorry you had to go through all of that trouble, my lb7 bridge took all of 3 minutes to remove :thumb: :woott: and it's 1 piece :D also didn't have to open cooling system :cool:
 

N2BRK

Well-known member
Dec 31, 2009
1,902
220
63
I saw that recommendation but it did not work for me. I still did not have room enough to sneak it past. I grabbed an oscillating tool and a few seconds later the head was cut off and then it easily came out. I've read where other LMM guys have had the same problem.