Hpop reservoir drains overnite

[JJR]

Friend of mine has 2000 excursion and overnite the hpop reservoir is draining down causing the start, stall, long crank till start then runs fine. Does not do it after initial morning start fine the rest of the day. Truck has no signs of a external leak anywhere and does not smoke out the exhaust anytime (so thinking injector o-rings are fine). Replaced the lpop with the Melling pump and checked and replaced the anti-drainback checkball and spring. Still leaks down. Where else or what else can be leaking still ? Truck has 150,000 miles.

[JJR]

Any techies around? Bump.

[rebelman20]

heres a for you

[JJR]

Anyone.

[optimus]

this is a shot in the dark could it be draining back into the low pressure oil pump? maybe a tech will chime in but i remember reading a thread a couple weeks ago talking about the LPOP wearing on the cover causing too much clearance if it has it maybe draining back over night.. hope its not though its a expensive fix.

[dray8165]

Check the one-way valve - you can take it off from above - it may have corroded or have a foreign body lodged in it.

[JJR]

Aready replaced one way valve and the lpop. Front cover had no scoring and was smooth and clean. Is it possible to drain thru the hpop? Checked hpop pressures and they checked out fine. What the h*** this thing is pissing me off.

[dray8165]

The HPOP feeds out through the high pressure oil lines and into the high pressure oil rails. If you have a substantial injector o-ring leak, I could see you losing oil that way. Are you using any oil?

It has to be going out the inlet (which the one way valve should have fixed) or the outlet....

[JJR]

Does not seem to use any oil nor does it smoke of any sort on startup which I think it would if the o-rings were leaking oil. Also on start up hpop builds pressure immediatly until the point where the reservoir runs out of oil and the truck dies. Looking at the feed from the lpop it uses a stove pipe like tube that fills from the top of the reservoir so i don't see it leaking that way. I think that check ball is just a priority valve that directs the oil from the lpop to the resevoir until the point were it builds pressure and closes directing the oil to the valve train.

[dray8165]

I think I misunderstood your problem. I thought you were draining down while it wasn't running. You are saying that the HPOP reservoir empties while the truck is running, right?

One correction to your thought process - lower injector o-rings will cause oil to leak into the fuel rails, being burned - sometimes causing smoking. Leaking upper injector o-rings will leak upwards, into the under valve cover area, which drains back to the pan.

When you say no scoring on the front cover of the LPOP, you do mean the front cover of the motor, right? The cover for the LPOP doesn't matter. (i.e., you would have to pull the pump and look at the cover behind the pump)

There can only be two explanations - the HPOP is pumping oil out too fast (still leaking injector o-rings) or the LPOP isn't providing oil fast enough (worn pump gears OR leaking oil pickup)

The test for the oil pickup tube is to overfill by about a gallon, and jack the back of the truck up as high as you can.