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late HPOP test device build

4290 Views 55 Replies 7 Participants Last post by  bismic
Hello Gentlemen,
I would like to build a device to test second/late generation HPOPs.
To see how they work I have started to disassemble a pump.

Can anyone tell me how these inserts are fixed in the housing? I can't hammer them in, nor can I pull them out with an impact hammer.

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"Stuff" I have accumulated ...................

Credit to FordDoctor, CNCFab, DieselSite (hopefully they do not mind that links to their information is copied and pasted.

Failure mechanism in the 03-04 HPOP's - and possible "fix":​
Failure areas:​
03-04.5 HPOP issues include a housing weakness (back plate wear-out) and swash plate issues (a light press fit is intended to hold the swash plate in place but apparently they can spin and cause failure). Also, there is documentation on rotating cylinder cracking. Wikipedia states that the gears were weak and cracked.​
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I am thinking that many of the "bad" pumps have suffered from the swashplate holder rotating in the bore -- the location affects the timing of the pistons and valve plate > then the pumps ability to move oil. Just a simple roll pin to locate that part would be a good fix

The brass valve plate in the pictures is junk -- those scratches connecting the valve ports are a killer in this style of pump -- the higher the pressure the pump is making, the worse the lifting affect is on the plates -- this causes the whole cylinder block to lift from the valve plate and spew oil from between the cylinder and valve plate , rather than deliver out the pressure port -- when the pressure called for is reduced, or the system is shut down, than the plates will come back into contact -- and pumping will seen normal again, until high pressure is reached -- the no or low pressure again as the plates separate

I have ran into this scenario many times with the machines I work on -- a pump will flow almost to spec at lower pressures but as the max is reached the flow drops off all of a sudden -- testing with gauges and a flow meter

Not the valve plate, it is keyed as you mention -- the problem is the "plug" which contains the swash plate, that is the part that is not keyed, in some / most of these pumps

Maybe that is not the best description, so here goes -- the part that contains the swash plate and rear bearing, has to be indexed to the valve plate, for the pump to work properly
this "plug" is just a press fit in the pumps I have seen -- A very poor design -- A locating pin or protrusion to lock that part would have been good

Reference Hartwig's post, the first picture -- the part the pistons are sitting in
This was part of the conclusion from the Machinest's WorkShop magazine and, from my interpretation, the description given by FordDoctor ("a light press fit is intended to hold the swash plate in place").

A lot more of an issue than simple priming procedures (not that priming the pump isn't a good idea).

EDIT - for the record (from a thread 2 years ago):
"I am not saying that properly priming the OEM pump wouldn't increase its reliability. No doubt it would. Seen that in industry MANY times. To what extent it would help, who knows."
A lot of good information in this thread, and it is an enjoyable read. Thanks to @Hartwig and @Hydro.

Ultimately, I wonder about the availability of re-manufactured 03/04 HPOPs that have actually had these issues addressed.

While DieselSite and CNCFab have not shared all the details of their improvements, I would suspect that they have addressed them since their reliability record seems to be very good (now that we have a significant number of years of people running them). I also suspect no other re-manufacturer has addressed them, but that is just a suspicion and an opinion.

Anyone have a recently purchased re-manufactured 03/04 Motorcraft HPOP available for testing??

I would throw $20 into a fund to purchase one for forensics just to see if anything has significantly changed in recent years of re-manufacturing.

As far as dismissing anything - that is jumping to conclusions a bit, but the LPOP fills very quickly even at low rpm.
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