Early 99 no oil pressure in hpop reservoir!!!
 

ok the other day i was driving along and noticed my op gauge on the dash drop to 0 and the dummy light came on.. me knowing the truck wont run with out op drive home. i replaced the op gauge switch and still read zero so i put a manual gauge on the hpop res. and started the truck, it stays at zero... im at a loss here on this thing. i have changed the oil and filter thinking maybe the filter collapsed and it still reads zero. if i rev the truck up to 2k it reads 5 psi but anything below that its at 0, idk what to look into from here. all info is greatly appreciated. TIA!

Sounds like a broken LPOP...

There is another port down by the oil filter, check the pressure there.

does the truck run and drive at all. the truck needs 550 psi mini output from the hpop to even start

well testing pressure from the plug on top of the HPOP resivoir is pre HPOP. so if the resivoir isn't even getting oil how can the HPOP get oil to the injectors? i'd say LPOP.

i checked the lpop this am and it only has 10 psi at idle and if i revv it the op will clime with the rpms to 40lbs at 2k rpm..

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anyone have a oilflow chart?

look around on this site. there might be one some where.

ok i changed the lpop and nothing changed???

hmmm. there was a similar post on this site a while back. on the inside of the front cover there is a plug that actually fell out causing the no oil pressure problem. that post was on the old bodies tho. but it could be your problem. but don't quote me on it.

found a broke rocker arm

well that's a problem. how many miles are on the truck?

I was goin to say it sounds like you have something just dumping oil back into the pan. If your not getting any psi like that.

How does a broken rocker arm cause no LPOP??? Do you have a lifter that is broken?

Is the key way on the crank for the lpop still there and good?

the broken rocker would have nothing to do with the pressure. if the key way is gone wouldn't that create a lot of metal particles in the front of the engine? that would put up a red flag to me.

The broken rocker arm would make it possible for the lifter to blow apart which would cause a large oil dump back into the pan and lower the pressure.

possible. i'm not going to agree or disagree with that because i'm not framiliar with th 7.3 to that extent.

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if the lifter blew apart, wouldn't there be some what big pieces of metal in the oil pan?

The inside parts of the lifter are no bigger than your pinkey and might not fall into the pan. They might land in the lifter galley right by the lifter body which should be in the lifter bore.

A broken rocker arm will simply not allow the valve to open and let the push rod do what ever it wants...

The lifter is held in with a keeper.

The lifter has a retainer holding it in the lifter bore and there is a clip holding the lifter parts inside it but when the rocker arm breaks I have seen many times that the pushrod bouncing around knocked the clip out and let the internal parts pop out of the lifter.

Thats possible I guess, but that would be a lifter issue, not a rocker issue...