12 Valve CTD Oil pressure drop???

[Zombie]

The truck: 1998 12 Valve Extended Cab Shortbed Auto (yeah... that is correct).
Truck has a suncoast tranny with around 40K on it, and about 120K on the truck and motor. 4" MBRP Exhaust turbo to tail, and banks goodies all over, including the bigger turbo and big head wastegate.
I drove it to vegas saturday, picking up a uHaul 12x6 trailer in mesquite.
The issue: When I got off the freeway in vegas, and came to a complete stop, the oil pressure guage dropped to zero, dash light came on, warning chimed, etc... but the motor didn't sound like it was off pressure.
When I start it, I can hear the oil pressure come up before the guage moves... seriously... I'm not spider man or anything, it's a very distinct sound difference, and it sounded like it had oil. I popped it into neutral, and gave it a little blip of throttle, and the guage came right back up.
It did the same thing when I stopped in mesquite for fuel on the way back, but did not do it in SLC when I got home.

My theory is that the sender for the oil pressure guage is going soft, and in the higher heat in mesquite and vegas, combined with a good long freeway run behind it, it lost the pressure. Like I said, It didn't SOUND like it lost oil pressure, but I suppose there is the possibility that it did loose oil pressure, but hadn't lost the residual coating before I blipped it back up.

Is there a record of failure in high heat from oil pressure senders or oil pumps in the 12 valve?

 

[LT.]

One thing that you may want to try right away is to mount a mechanical oil pressure guage in the cab. Your guage that is in your rig now is an electrical one which, as you already pointed out, may be failing. With the driving you described you did make the oil easier to pass by the, could be failing, sending unit, due to the heat and long drive as you pointed out. If you feel confident that you are not starving the engine of oil then use the mechanical guage to make sure of your hunches.

LT.

 

[Rot Box]

My 92 is experiencing the same problem--and I was sh$%ing bricks when it first started happening--exept my warning light does not come on. I now know that it is pretty common for the guages to wear out and read low or even zero psi.

As cheap as these engines are to replace i'd go for the mechanical verification only because your warning light is coming on also. I was under the impression that they ran off of a different sending unit, but I'm not sure...

 

[I Lean]

I'd almost bet money it's your sending unit.