When at idle the oil gage will go to 0 and the light will come on, I have changed the oil pressure sensor and have put a real pressure gage on it. Using a "T" so I could have both gages hooked up at once. The real gage is about 10 psi at idle and the gage on the dash is showing 0 and the light is on. I know I should trust the real gage, but what would cause the gage in the dash to show 0 when the real gage is showing 10.

 

It is not a real gauge. Is is nothing but an idiot light that looks like a gauge.

 

i read somewhere where you should have 10lbs of oil pressure per 1k rpms. does that sound right??

 

The factory switch changes state at 6psi, so if it's changing at 10, it's defective.

But your engine is worn out, too. At 2000 RPM warmed up, it should make 40-60 psi. It should never drop to 10 - that's not enough to keep the lifters pumped up.

 

Steve83 when you say the switch may be defective, do you mean the sending unit on the block or the gage in the dash?

Thanks

 

yes sir, you are correct, 10 psi per 1000 rpm is needed to properly lubricate everything.

 

How many miles on the engine? When was the last time the oil filter was changed? Any metal in the oil?

JMC

 

Your truck (any Ford after 1986) doesn't have a sending unit - it has a 6 psi switch on the block. If it switches at 10psi, the switch is bad.

 

Well I did replace the switch on the block it is still going to nothing on the dash gage when at idle, the mecanical gage I also have hooked up is showing just a hair above 10 psi at idle, the truck has about 140,000 miles on it, but the engine was rebuilt about 2 years ago.

 

10 psi at idle is too low - you have some wear somewhere.

 

Yep - it's WORE out. You can try going up one or 2 grades in oil viscosity (the 1st number), but modular engines don't like thick oil. So if you're running 5W-XX right now, don't go thicker than 15W-XX.