Duramax Diesels Forum Truck of the Week
  #76  
Old 01-06-2017, 05:44 PM
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Cheeny23 Cheeny23 is offline
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Originally Posted by quadracer37 View Post
I would do a new injector return line assembly with check valve, and replacing the rail pressure sensor and electric relief valve is also a good idea. They might get by OK for a little while, but you dont want to end up stranded somewhere because of one of these items failing not long after the repairs.
he removed the whole fuel system to send out and cleaned at the same place that benched my injectors. If any of it is bad, he already knows to replace it. It's just money right
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  #77  
Old 01-11-2017, 06:53 AM
TakeAwayTheFear TakeAwayTheFear is offline
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So I have a 2015.5 and so does my step dad. Both are 3500 duallys I have 226k miles and he has 254k no problems. His buddy has a 13 or 14 2500 with well over 300k with no probs but my brother has a 15.5 2500 with 140 and his just took out the whole motor from what I heard yesterday....... all the trucks are used to transport campers all over the country. Mine and step dads have been tuned for the past 40-70k miles just for fuel economy and emissions. Was told it was a 40-50hp tune
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  #78  
Old 01-11-2017, 11:52 AM
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just so there is no confusion. bosch made no meaningful "updates" to these pumps since their introduction to correct the problem.

the biggest updates was coating changes to the roller follower and new body alloy (high silicone cast aluminum). the issue of the roller getting jammed up and not rolling on the cam will not be solved by this. also the bigger issue that seems to occur is the roller (and follower) turns 90 degrees to the cam and has no way to roll. this grinds a groove in the roller and cam sending metal into the fuel system.



all CP4s suffer from these failure modes, whether it is a CP4.1 or CP4.2. the design of the pump is the problem here. added lubrication MAY help extend the life of the pump but it seems that pumps still fail regardless.

the TDI club has this well documented with the CP4.1 used on the VW TDI
http://forums.tdiclub.com/showthread.php?t=299854
and
http://forums.tdiclub.com/showthread.php?t=286380
and of course my thread
http://forums.tdiclub.com/showthread.php?t=387252

the best guess and evidence as to why Bosch would make this change is to lower the cost of manufacturing. the CP3 has an almost all high strength steel body to handle the pressures, plus three precision ground/machined pistons, valves and related parts. in the CP3 each piston only makes one pressure stroke per a revaluation. the CP4 piston makes two. this is twice the strokes

the CP4 only has a steel piston head that retains the pressure. the body is all aluminum. there is only one piston in the CP4.1 and two pistons in the CP4.2. the parts count on the CP3 is several times higher than a CP4. being that a CP4 retails for roughly the same cost as a CP3 this was likely a way for bosch to increase profits. bean counters likely designed this pump.

what doesn't make sense is now they are paying more on the HPFP warranties along with replacement of contaminated parts as a result. whether they come out ahead is anyone's guess

luckily i am still driving an LMM so i don't have to worry there but i did experience a CP4.1 failure on my VW TDI. right now i am in the process of collecting the parts needed to convert that over to a CP3/R70 pump.

If my duramax had a CP4, converting it to a CP3 would be one of the first upgrades i did after the warranty was up
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Last edited by 2004LB7; 01-11-2017 at 12:02 PM.
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  #79  
Old 01-11-2017, 07:17 PM
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One thing Ive always wondered about the CP3 swap is how does a CP3 maintain the higher PSI that the LML requires (not to mention the fuel volume) when its essentially "half" a CP4?? Just curious.
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  #80  
Old 01-11-2017, 11:27 PM
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An excerpt from truck trend

"The CP3 is a radial-piston pump that can supply up to 29,000 psi in some applications and is perhaps the most well known and most modified high-pressure pump on the market."

"Next is the CP4, which is also made by Bosch. Although it has a higher number designation, the CP4 actually flows about 20 percent less fuel than its younger brother, the CP3. Found on ’11-to-present Power Stroke and Duramax engines, the CP4 is a more advanced pump despite flowing less fuel, with external high-pressure circuits and a maximum pressure of 29,000 psi."
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  #81  
Old 01-11-2017, 11:39 PM
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Quote:
Originally Posted by TheBac View Post
One thing Ive always wondered about the CP3 swap is how does a CP3 maintain the higher PSI that the LML requires (not to mention the fuel volume) when its essentially "half" a CP4?? Just curious.
Not sure on this but converted to a 10mm cp3 and that thing will hold 29 no prob on max effort
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  #82  
Old 01-18-2017, 10:23 AM
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i sent emails to the NHTSA and GM about it, and filed a formal complaint with the NHTSA. granted it's probably not going to be found as a "safety" issue, just trying to ruffle feathers at this point. I was in AZ for the weekend and got a call from someone at GM, and she asked me some questions, apologized for the inconvenience, blah blah, then she said she was going to reach out to my local dealer where I bought the truck and start a reimbursement claim process. not sure if anyone else has gone through it or been successful, but at this point, any money back in my pocket and I'd be happy. final bill was $8979 with the sdp cp3 kit, airdog 4g, and new injectors, the rest of the fuel system was fine, no contamination back to the tank. I'm friends with a few of the guys at the dealer, since we get all our personal and company vehicles there, so i'll follow up with them today and see what's going to happen with that claim.
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