Chevy and GMC Duramax Diesel Forum banner

1 - 20 of 220 Posts

·
Registered
Joined
·
19 Posts
Discussion Starter #1
I am hearing people talk about the concern with potential CP 4 pump failures. But I have not heard from anyone who can speak 1st hand as far as the actual nature of the failure

Specifically... What part(s) are actually failing And has anyone examined the failed part closely to identify cause of the failure.

Is there premature wear being found or are the parts not holding up under the demands of the pump within its required operating parameters.

I would like to know if there is (for example) any indication of any seals, rings, bearing, etc that are failing first and that being the cause of a much bigger failure.

Curious if anyone has that kind of information or can possibly show us a unit that has failed.

Thanks.


Sent from AutoGuide.com Free App
 

·
GMC..Professional Grade
Joined
·
3,962 Posts
From what I've read, it happens so fast that it would be hard to tell what failed first, because they grenade.
 

·
Registered
Joined
·
19 Posts
Discussion Starter #6 (Edited)
Joker... What causes the piston to do that? (Gall). Do these pumps see much heat? Is it from lack of fuel to the pump or possibly cavitation resulting in air getting into input side of pump?

Is this happening on stock trucks, tuned trucks, etc?

Is the kind of fuel we run today really a contributing factor? Not sure if I can completely buy into that theory?

If it a piston problem I can see how that can be catastrophic. But if it is a piston problem I also believe it is an relatively easy fix for GM to have Bosch upgrade newer units.

I am struggling with a unit being out there for 4 years or better and no one know any more now than 4 years ago.





Sent from AutoGuide.com Free App
 

·
jokerfabworx.com
Joined
·
3,657 Posts
Joker... Does it agall up as a result of


Sent from AutoGuide.com Free App
1. Sh*t fuel (back to scar ratings and general fuel quality)
2. Lack of lubrication (water in fuel is bad for pumps lubricated by diesel fuel AND/OR running the pump dry)
3. Straight-up faulty parts and or assembly (it happens)
 

·
jokerfabworx.com
Joined
·
3,657 Posts
Bosch clearly states that their CP4.2 pump requires 460 micron scar fuel or better. The lower the scar rating, the higher the lubricity.

The US standard for diesel fuel is 520 scar.

The Canadian standard for diesel fuel is 460 scar. It's no mystery why there have been fewer reported failures in, Canadaland.
 

·
Registered
Joined
·
2,539 Posts
If you tally up the amount of reported CP4.2 failures and compare it to the number of pumps that are still functioning in LMLs, the outlook isn't quite so grim.
Agree on the current overall failure rate 'today' but nobody can say what they'll be after some time in the field. Combine that with the hefty price tag that could strike anyone at any given moment and you can see why some of us are rightfully concerned and asking questions.
 

·
Registered
Joined
·
1,390 Posts
What's the ratio of cp4 failures to cp3 failures? Might be more than just bad fuel and poor lubrication. You never heard of cp3's failing at the rate that cp4's are.
 

·
Registered
Joined
·
19 Posts
Discussion Starter #12
When I hear "piston pile up on cylinder wall". I think contaminated fuel or lack of fuel.

Has GM or Bosch ever provided any feedback to consumer as to possible causes or prevention


Sent from AutoGuide.com Free App
 

·
jokerfabworx.com
Joined
·
3,657 Posts
Agree on the current overall failure rate 'today' but nobody can say what they'll be after some time in the field. Combine that with the hefty price tag that could strike anyone at any given moment and you can see why some of us are rightfully concerned and asking questions.
Just be happy that GM is covering pump failures, whereas Ford is not. :thumb

What's the ratio of cp4 failures to cp3 failures? Might be more than just bad fuel and poor lubrication. You never heard of cp3's failing at the rate that cp4's are.
More CP4.2's. However, the 4.2 produces higher pressure and has lower(thanks sandman) tolerances than the CP3 platform. Still running the same fuel that worked in the CP3. I think that fuel is a big part of the failure rate.
 

·
Most Known Unknown
Joined
·
29,437 Posts

·
jokerfabworx.com
Joined
·
3,657 Posts
When I hear "piston pile up on cylinder wall". I think contaminated fuel or lack of fuel.

Has GM or Bosch ever provided any feedback to consumer as to possible causes or prevention


Sent from AutoGuide.com Free App
You nailed it.

Yeah... 460 micron scar or better fuel. :p
 

·
Registered
Joined
·
19 Posts
Discussion Starter #16
So... Would it be suggested that people run a lift pump and a possible fuel additive to prevent this?

I was not aware of the SCAR ratings you guys are referring to. But, If US diesel does not comply, why is Bosch/GM continuing to put these units out there.




Sent from AutoGuide.com Free App
 

·
Registered
Joined
·
2,539 Posts
Just be happy that GM is covering pump failures, whereas Ford is not. :thumb

True, but at some point well all be out of warranty and on our own.

More CP4.2's. However, the 4.2 produces higher pressure and has higher tolerances than the CP3 platform. Still running the same fuel that worked in the CP3. I think that fuel is a big part of the failure rate.
I think u meant to say CP4's require lower or tighter tolerances.
 

·
Registered
Joined
·
2,539 Posts
So... Would it be suggested that people run a lift pump and a possible fuel additive to prevent this?

I was not aware of the SCAR ratings you guys are referring to. But, If US diesel does not comply, why is Bosch/GM continuing to put these units out there.




Sent from AutoGuide.com Free App
Yes but installing a lift pump will likely void your warranty. Go figure.
 

·
Registered
Joined
·
19 Posts
Discussion Starter #19
Do you really think GM would void a warranty on a truck equipped with a lift pump... Wait... Don't answer that!

With that said... I can't see any way a lift pump can be linked as a contributing factor for a CP pump failure.

Even if the lift pump lost power and stopped pumping. The CP pump would not be starved and would be able to continue to draw fuel from the tank.

Right?


Sent from AutoGuide.com Free App
 

·
jokerfabworx.com
Joined
·
3,657 Posts
So... Would it be suggested that people run a lift pump and a possible fuel additive to prevent this?

I was not aware of the SCAR ratings you guys are referring to. But, If US diesel does not comply, why is Bosch/GM continuing to put these units out there.


Sent from AutoGuide.com Free App
A lift pump and extra filtration shouldn't hurt. Giving the injection pump a bit of positive pressure on its supply line will relieve it of it's lifting duties.

Additives to increase lubricity are a good idea, as long as they are compatible with your emissions system. You have to experiment for yourself with additives and dosages. Some good info if you read though his. ( http://www.duramaxforum.com/forum/alternative-fuels-diesel-additives-lubricants/294058-fuel-additives.html ) Just sift through the bullsh*t. :rofl

I think u meant to say CP4's require lower or tighter tolerances.
You are correct. :thumb
 
1 - 20 of 220 Posts
Top