CP3 Is Leaking
#21
03-24-2008, 01:59 PM
Last edited by DB Admin; 03-24-2008 at 02:48 PM.
#22
03-24-2008, 02:01 PM
Diesel Bomber
Just on the outside looking in-
IIRC the Duramax didn't have a lift pump in the trucks until 2005 or so but the Dodges with a CP3 have always had a lift pump.
So maybe the lift pump is the reason you guys have different results? Maybe the earlier Duramax trucks could have this issues cause a no start because they didn't have the lift pump to force feed the fuel?
IIRC the Duramax didn't have a lift pump in the trucks until 2005 or so but the Dodges with a CP3 have always had a lift pump.
So maybe the lift pump is the reason you guys have different results? Maybe the earlier Duramax trucks could have this issues cause a no start because they didn't have the lift pump to force feed the fuel?
#23
03-24-2008, 02:02 PM
#24
03-24-2008, 02:57 PM
You just cant say a fuel leak EVEN on a PRESSURIZED SYSTEM wont effect starting. None of us will ever know everything.
He is correct on a few things, I'm not trying to say he's not. I know for a fact, EVEN on a CP3 system with a pump that if the factory lift pump is week it can allow fuel to back flow!
The tank is lower than the pump, It can and will siphon back and cause a hard start issue!
He's also right that most pumps will seep a little fuel , But much more than a seep is a concern. I was under the understanding it was a decent size leak!
He is correct on a few things, I'm not trying to say he's not. I know for a fact, EVEN on a CP3 system with a pump that if the factory lift pump is week it can allow fuel to back flow!
The tank is lower than the pump, It can and will siphon back and cause a hard start issue!
He's also right that most pumps will seep a little fuel , But much more than a seep is a concern. I was under the understanding it was a decent size leak!
Last edited by Johnny Cetane; 03-24-2008 at 03:02 PM.
#25
03-24-2008, 03:01 PM
Diesel Wrench
My 02 LB7 had a leaking CP3 and it caused hard starting and rough idle. Repaired the CP3 leaks and the problem went away.
As for the dissimilar metals, they are put through the proper heat treat process to maintain tolerance so there is never to be any leakage. Both metals will expand and contract at the same rate until the alloy reaches -60*F. At that point the aluminum will contract at a slightly faster rate then a 4130 or 4140 with Rockwell C.
And I do stand corrected on the "sucking air". I should been ashamed of myself for saying such. What is really happening is loss of positive displacement.
As for the dissimilar metals, they are put through the proper heat treat process to maintain tolerance so there is never to be any leakage. Both metals will expand and contract at the same rate until the alloy reaches -60*F. At that point the aluminum will contract at a slightly faster rate then a 4130 or 4140 with Rockwell C.
And I do stand corrected on the "sucking air". I should been ashamed of myself for saying such. What is really happening is loss of positive displacement.
I agree the expansion rates should not make a difference but that is obviously is what is happening with the pump. How else would explain leaking only in the colder months and none when ambient tempos remain above 60 degrees or so? How do explain resealing the pump with larger diameter o-rings will in most cases eliminate and others considerably slow the leakage?
Its the temp difference from ambient to operating that I see causing the leaks. If you have another theory please contribute.
#26
03-24-2008, 03:03 PM
Diesel Bomber
#27
03-24-2008, 03:10 PM
The Duramax DRAWS fuel from the tank, it is not pressure fed. Small leaks do not impact a pressure system like they do one relying on a vacuum to draw the liquid. The Cummins application is, and always has been, pressurized thru smaller lines.
I agree the expansion rates should not make a difference but that is obviously is what is happening with the pump. How else would explain leaking only in the colder months and none when ambient tempos remain above 60 degrees or so? How do explain resealing the pump with larger diameter o-rings will in most cases eliminate and others considerably slow the leakage?
Its the temp difference from ambient to operating that I see causing the leaks. If you have another theory please contribute.
I agree the expansion rates should not make a difference but that is obviously is what is happening with the pump. How else would explain leaking only in the colder months and none when ambient tempos remain above 60 degrees or so? How do explain resealing the pump with larger diameter o-rings will in most cases eliminate and others considerably slow the leakage?
Its the temp difference from ambient to operating that I see causing the leaks. If you have another theory please contribute.
I'm quite well aware of that. Re-read my post #23. However, my trucks ARE pressure fed.
The metals are not getting out of tolerance. Replacing the O-rings with larger units isnt the answer either. If a 70 durometer HNBR seal's and o-rings were used we wouldnt see this issue. They got cheap on the material.
This thread is being pulled way off course. I would be glad to discuss the design and Engineering of the CP3 with anyone in pm's, chat or even another thread but not here. Lets move on to help fix wildbill's problem and take up any Engineering or Technical discussion somewhere else.
Last edited by DangerousDuramax; 03-24-2008 at 03:17 PM.
The following users liked this post:
mysterync (03-24-2008)
#28
03-24-2008, 03:45 PM
Diesel Wrench
First, let me aplogize for the inadevertent words that seem to be upsetting people.
I called NO PERSON out or any way shape or form denigrated their opinon.
The statement was example only that I am direct in my statements. If I think you are wrong I WILL call you on it but nicely. I will also provide an alternate theory and explain why I think your wrong. If you don't like discussion and a certain amount of dissension then these forums are the wrong place to be.
DangerousDuramax, I pointedly disagree with your contention this thread is going off track. Its now ON track because I pointed a few holes in the theories. You cannot compare the Duramax systems to the Dodge systems. They are totally different and have their own little quirks. I saw this thread headed down a dead end road becuase I HAVE BEEN THERE! Isn't that what these discussions are for? I am simply sharing my experiences and what I have found thru experience.
Furthermore, DangerousDuramax, look at your own attitude before offering me any advice. Where do you derive authority to decide what is on or off track? Get over yourself. You have the same capacity to be wrong as the rest of us and wanting to drop ANY discussion that contradicts your opinions makes you look a little closed minded. (Moderator delete if you must but take into account there is a least one left here that wants a fight rather than dialog. I have no problem either way)
I called NO PERSON out or any way shape or form denigrated their opinon.
The statement was example only that I am direct in my statements. If I think you are wrong I WILL call you on it but nicely. I will also provide an alternate theory and explain why I think your wrong. If you don't like discussion and a certain amount of dissension then these forums are the wrong place to be.
DangerousDuramax, I pointedly disagree with your contention this thread is going off track. Its now ON track because I pointed a few holes in the theories. You cannot compare the Duramax systems to the Dodge systems. They are totally different and have their own little quirks. I saw this thread headed down a dead end road becuase I HAVE BEEN THERE! Isn't that what these discussions are for? I am simply sharing my experiences and what I have found thru experience.
Furthermore, DangerousDuramax, look at your own attitude before offering me any advice. Where do you derive authority to decide what is on or off track? Get over yourself. You have the same capacity to be wrong as the rest of us and wanting to drop ANY discussion that contradicts your opinions makes you look a little closed minded. (Moderator delete if you must but take into account there is a least one left here that wants a fight rather than dialog. I have no problem either way)
#29
03-24-2008, 03:51 PM
Banned
Thanks for your Opinions !
And yes its never meant to be construed that staff is here to tell anyone whats right and wrong , its our Duty to the site to Try to keep it Moving Forwards and Productive in a manner in which others would like to join in .
Calling blaspheme dont make anyone happy for sure , And like tracy said we really do want to her about your experiences with the topic and feel free to share in a manner in which your not ******* others if possible
No ones right 100% of the time , Whats right is facts gained from personal experiences ...Do Share
DM
And yes its never meant to be construed that staff is here to tell anyone whats right and wrong , its our Duty to the site to Try to keep it Moving Forwards and Productive in a manner in which others would like to join in .
Calling blaspheme dont make anyone happy for sure , And like tracy said we really do want to her about your experiences with the topic and feel free to share in a manner in which your not ******* others if possible
No ones right 100% of the time , Whats right is facts gained from personal experiences ...Do Share
DM
#30
03-24-2008, 06:04 PM
Must be Monday!
---AutoMerged DoublePost---
Not sure if it was the 36 deg. this morning, or it being plugged in but it started and idled much smoother. I reprogrammed Smarty to moderate torque and when it told me to unplug I waited 15 sec. then another 15 sec. after I unplugged it. So we'll see what happens in the next few days.
---AutoMerged DoublePost---
Not sure if it was the 36 deg. this morning, or it being plugged in but it started and idled much smoother. I reprogrammed Smarty to moderate torque and when it told me to unplug I waited 15 sec. then another 15 sec. after I unplugged it. So we'll see what happens in the next few days.
Last edited by wildbill; 03-24-2008 at 06:04 PM. Reason: Automerged Doublepost
