Low oil pressure

[u2slow]

heres another scenario---brother had a 88 7.3..start,good psi, as soon as warm,zero. so,took off the rear cooler header--and the relief valve was----------------STUCK OPEN!!!!!!-------i took it home,polished the valve with FINE scotchbrite, and staked it back together. he had good oil pressure, even on the day he traded it off for a way newer one. we went thru a bunch of other things before discovering this-----all it takes is one little particle to get in that valve,jam it sideways, and goodbye oil pressure--

My oil filter bypass valve has a snap ring. On the vans, does this mean the regulator valve has a snap ring also? (on F-series, when one is snap ringed, BOTH are)

Guess I need to pull this cooler for an inspection.

Anyone know what it takes to get the cooler out without taking out the engine?

 

[aaklingler]

I've been doing a little research of my own on the oiling system because I think I might be having some oiling problems. From looking at the oil diagram of a psd I don't think that regulator valve bad bearings would cause low oil pressure on the gauge because form the lpop oil either goes to the hpop or to the cooler, filter, regulator and then the rest of the motor and the pressure switch is located at the hpop. I'm working on a motor that is noisy, I've pulled a valve cover and I don't see anything wrong but the only oil I see is what comes out of the injector, is that normal? Feel free to correct me if I'm wrong.

 

[u2slow]

From looking at the oil diagram of a psd I don't think that regulator valve bad bearings would cause low oil pressure on the gauge because form the lpop oil either goes to the hpop or to the cooler, filter, regulator and then the rest of the motor and the pressure switch is located at the hpop.

The hpop is only fed directly from the lube pump momentarily until the rest of the lube oil system primes up. Once the galleries are pressurized, the 'short-circuit' valve closes, and the hpop reservoir level is maintained via the main gallery supply.

For this reason, a stuck relief valve (in the oil cooler header) can divert a LOT of oil directly back into the sump before it even gets to the bearings.

The pressure sensor on the hpop reservoir is actually a pressure switch It operates at about 5psi to register a mid-range oil pressure reading on the OE oil pressure 'gauge'.

 

[aaklingler]

I didn't know there was a 'short-circuit' valve, but if you say so I believe you. That would mean that if the relief valve is stuck there wouldn't be oil coming through the gallery to the hpop so the hpop would be getting oil from the short circuit so the pressure switch should still be seeing pressure, correct?