HPOP draining overnight? FIXED!!
 

So we have a problem, my HPOP is draining over night, truck can be use all day with no problem, let it sit overnight and the thing dries up. I opened the HPOP check plug and it is completely dry, I bought a new MC IPR and same thing (needed one anyway unkown age or miles on my spares)
I had the same problem with my old mill and im 100% sure its not the HPOP gasket, timing cover has no damage (used an e99 timing cover) injector O rings cant be as the rails are full of oil, the oil cooler end caps are from the e99 as well (the engine never suffer from this)Its not the check valve in the block either, that only leaves the HPOP?

Any of you guys ever had this problem? What other thing could make this happen that im missing? There was one guy at the org with the same problem but the guy never reported back.

Additional info my HPOP is a T500 and was also ran on the old mill, has the check ball on it, I used the 96-03 HPOP gasket, some of you say it wouldn't matter but lets not forget it also did this in the old mill..

No Start - Dry Reservoir

Probable Causes

To understand the causes of the no start and identify the causes to this problem, it is important to identify the failure mode. If the engine:

• "Started and ran approximately 15 seconds and stalled". The cause may be a lack of oil supplied by the lube system.

Or if the engine:

• "Did not start and reservoir was found dry"

Possibilities include reservoir leak down: Caused by a leaking check valve in the high pressure oil pump, porous oil reservoir, or reservoir pump down which may occur during cranking and no start conditions caused by CMP circuit or other electronic control circuit failures. Procedures

"Started and Ran Approximately 15 Seconds and Stalled"

This condition assumes that the reservoir was full when the engine start was attempted or when the engine started normally and would stall after 15 seconds of running.

• Refill the reservoir and verify the start and stall condition.
• Remove, inspect and measure clearances in the lube oil pump. (Figure 60.) Upon removal of the lube oil pump, inspect the front cover surface for gouging or deep scratching, inspect the oil pump for damage or wear. Using a straightedge and feeler gauge, measure the height clearance between the oil pump housing and the inner rotor and outer rotor. Specification is 0.001" - 0.003" (0.02 mm - 0.08 mm). Using a feeler gauge, measure the clearance between the outer rotor and the oil pump housing. Specification is 0.028" - 0.032" (0.72 mm - 0.81 mm).

https://www.thedieselstop.com/faq/94...es/gg1383a.gifFigure 60. - Lube Oil Pump Inspection and Measurement

"Did Not Start and Reservoir Was Found Dry"

• Refill the reservoir and attempt to start the engine.
• If the engine does not start, perform the procedures in the Hard Start/No Start Diagnostic form. The tests on this form will discern if the essential elements required to start are present (e.g., CMP camshaft position signal, battery voltage, fuel and fuel pressure, ICP injection control pressure, etc.).
• If the engine starts, the low reservoir problem may be caused by reservoir leak after a prolonged period of not running.
• Road test the vehicle for a minimum of 10 miles to assure that all air is purged from the injection control pressure system. Check oil level in reservoir to assure that it is full and let sit over night.
• Inspect oil level (Figure 61.) the next morning (prior to starting engine) to determine if leak down has occurred.
• The only paths for leakage is a check ball internal to the high pressure oil pump or through a porous reservoir or front cover. (NOTE: The check ball has been eliminated in MY96 and newer due to a stand pipe added to the reservoir.)
• Leakage past the check valve in the high pressure pump may be intermittent. The check valve internal to the pump is not serviceable. 1996 and later high pressure pumps do not have internal check valves. If the high pressure pump is suspect, replace it. (Figure 62.) (Note: The IPR injector pressure regulator valve which is mounted in the pump should not cause a leak down problem and does not require replacement when a high pressure pump is replaced.)
• Porosity through a reservoir or front cover casting is unlikely. Leakage through a porous casting would also be diagnosed as a consistent problem and should not be a case of intermittent leak down. If porosity is suspected, it is recommended to replace the reservoir first.

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I like the manuals but they are old. They might not tell the whole story. It's a good place to start but who knows where you'll end up?

Thanks for the trouble shooting info, unfortunatly according to the chart this only leaves the HPOP to be the culprit..

Truck runs fine all day long, even if it sits for more than 6hrs it will start, this happens overnight at least in a 9ish hour span, oil pressure builds quick too according to the dummy gauge.

94.5-95 HPOP with a e99 front timing cover.

I read that post about the HPOP leaking down and thought I had that issue when mine was starting hard.

I would put on a pressure gauge at the HPOP plug and see how long it takes for pressure to drop once engine is turned off.


Maybe you can open the plate for the HPOP gear, fill HPOP with oil, add in compressed air to HPOP res and see if the seal leaks? Might have to test cold and hot

I asked if it would made a difference and some guys said no, should work. But the old engine did this as well.

Aren't internet forums great?

On the plus side, at least your pickup does an "HPOP oil change" every night so you don't have to worry about that like the internet would have you believe is necessary.

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