Engine/Transmission (1998.5 - 2002) What part-parts fail in the VP44??

[Gonzo 1066]

I hear of VP44 failures and was wondering what exactly fails in those pumps?? Do they twist a drive shaft due to head siezing? Is it a controll linkage? Help me out here.

 

[jrandol]

Hey gonzo, getting way beyond my understanding of the inner workings of the VP but I think this is a pretty good article. Maybe it'll give you the info you are looking for.



http://www.bluechipdiesel.com/Bosch-VP44.htm

 

[Gonzo 1066]

Thanks

Thanks for the reply jrandol. This will be a great help, I am glad that there is someone out there that has actually taken one of these broken pumps apart to find out WHAT THE HECK FAILS!!!!!!

I had assumed it was a rotor sezie because of my experience with rotory injection pumps in diesel tractor pulling. But it is better to know. Thanks again. Gonzo

 

[A Johnson]

The failures I have seen: 1-Timing piston galled or stuck in its bore.

2-Internal vane pump scored on the vanes.

3-Broken pulsation dampner allows lift pump pressure to hold rollers awy from internal cam ring resulting in a hard start, worse when warm fuel is present.

4-Burnt pins on the connector

5-The ECM on the VP-44 had some solder joint issues. as well as other things I have not seen for myself.



I think it was Evan Beck that said it best " If you ever get a chance to tear a VP-44 apart do it, you may learn something". Not an exact quote but pretty close.



A Johnson

 

[Evan A. Beck]

Close enough.

 

[24VChev]

VP44 failures

I just changed out a VP44 that failed, the first symotoms of something wrong was a poor idle and lack of power at WOT. The truck seemed to make more power at 1/2 throttle than full throttle.



I took the pump apart and it appears that the plungers had seized in the head, the drive plate inside then snapped in half.



This truck has a comp on it and is always set to 5X5. It has been bombed for 50,000 mles and it is first pump failure. The lift pump is also original and still makes good PSI.



I have only looked at the VP 44 for about 10 min once I took it appart. I will have a better look at it when I find more time.



I will post some pics of it







Malcolm

 

[d2500]

Rebuild parts?

Does anybody have any suggestions for sources of rebuild parts? Or are we relegated to the mercy of DC? I've gotta believe there's someone out there that can fab up a new piston or a vane pump/rotor!

 

[A Johnson]

There isn't anything special as far as rebuilding as far as I can see. The problem as I understand it, is the equiptment needed for assembly, specificaly optical equiptment to set the internal static timing. The tone wheel inside is not keyed to the main drive shaft and is set-up (or measured) with an electrical eye, therefore the need for offset keys of varying degrees to get the static timing correct. You can probably buy the parts from your local Bosch service center.



A Johnson

 

[jrandol]

Its my understanding that Central Motive Power in Denver can now work on the VP44. I have not verified this myself yet but this is what I hear. Having injection shops capable of this will mean great savings for us all!