hello and I hope someone out there can help me. It all started driving down the road my check gauges light came on I looked down and there was no oil pressure.I changed the oil put in new 1540 Rotella . put original cap back on made sure it was a Motorcraft oil filter. I also put in a new sending unit.doing some research and was told it was my low pressure oil pump so I changed out the low pressure oil pump installed a new one new cover put it back together now I have hard starts but it will eventually .crank.when the engine does crank as long as the RPM's are above 1000 the oil pressure gauge reads normal if it drops less than a thousand RPMs the gauge drops to zero.I plan on installing a mechanical oil pressure gauge just to make sure or just to see the actual pressure but I know this won't fix it.any suggestions on what to do to fix it or make things better would be greatly appreciated thanks a lot I'll be waiting for an answer any suggestions are appreciated

 

Do you know if the STC has been fixed?

 

Thanks for the reply Heavy Assualt. As far as I know it has not. (The STC) Would you recommend this first and change the IPR at the same time?
The truck has never cut off while driving, this is telling me the oil pump is working right? It would have to be pumping for it to crank just has to build pressure. Let me know about the IPR.
Thanks for your help on this.

 

I'm not up to speed on the symptoms but I know the STC will cause issues. Figured I'd throw it out there for you to check.

 

HeavyAssault is right. If your truck is late 2004 or newer it had the STC fitting. If it hasn't been fixed, it needs to be. This fitting is like the fitting on an air compressor hose, only built to handle much higher pressures. These fittings fail, period. They never should have used that fitting in this application. There's a replacement part that fixes the problem by eliminating the fitting entirely.
However, a bad STC cannot cause a low reading on the oil pressure gauge. The gauge on the dash shows oil pressure on the low pressure system, whereas, the STC is located on the high pressure oil system.

Your primary concern now, though, is fixing the low oil pressure reading. Since you eliminated the oil pump as a possibility, the pressure sensor might be bad. If it were me, I would temporarily replace the oil sensor with a mechanical gauge. If this reads normal, pull the gauge back out and replace the sensor.

One thing to note about the oil pressure gauge; it's not a linear gauge like you would think. It won't show any reading when the pressure is lower than a certain value. As the oil pressure comes up, the gauge will show zero until the pressure is up to a minimum value, then the gauge moves to the normal indication. From the point I begin cranking my engine over, the gauge reads zero for 2 to 3 seconds, then it moves up to normal. There is nothing wrong with this behavior. It acts this way because of the way the gauge is designed....like I said above.

After you resolve the pressure issue, then go after the STC issue. When I fixed the STC issue on my truck, I replaced the IPR, the EGR and oil coolers at the same time, since I was in there. I didn't want to tear into it a 2nd time. This was at 80,000 miles. It's got 120,000 on it now and running great.

 

Thanks for the info the build date on my truck is Feb 2004. this being the case I should change the STC fitting correct.
What about the engine oil pressure regulator would there be a chance in it going bad and if so where is it on the engine?

 

You may have old style since yours is February. . Look on passenger valve cover. If your IPR is on front top of cover you have newer style. If you have IPR and ICP together under turbo u have early style.

 

Ok looking at my oil pump and with the pump still mounted standing in front of the truck with the gear towards the back of the truck on the right hand side there's two mounting bolts where it mounts to the intake there's a empty hole above those I'm told there's supposed to be a ball bearing in that hole if this is correct somebody please advise and is there a way to fix that without replacing the whole pump.