I've got a question. My 94 F150 has a 302 approx 239,000 miles on it. It start having a little lower than normal oiil pressure on the gauge. After it warms up the gauge goes to pegged out on low. Could this be the oil pump? I know the oil gets thinner when at temp. Or am I way off.

 

Does the motor knock or make any other noise? The gauge in the dash is nothing more than a "smart" idiot light. It has a switch where the old sending unit used to be, and there is a resistor on the gauge. It's really only going to read two things, nothing or mid range. The mid range will fluctuate some with voltage.

 

My Mech told me these trucks (we have the same truck) are known for the oil screen getting clogged.

 

gauge moves if oil pressure drops below 7 psi.

i am with stealthwyvern, i bet it is the oil pickup.

check pressure with mechanical gauge.

 

Straight 30 weight oil gets thinner as it heats up. But, 10W30 or 10W40 get thicker as they heat up. The numbers are the oil viscosity when cold and then when hot. It's some crazy effect of polymer chains shrinking in legnth when they get hot.

I have this same problem. I have also heard to change the oil pickup and perhaps the pump. But, I have also ehard that it's not a very fun job to get at the stuff. You have to jack the engine up a few inches to get the oil pan out. I haven't done that yet, but there are lots of posts on that.

 

I've got a 95 and every 10,000 mi I replace the oil sending unit,which only cost 10 bucks, my oil pressure gauge reads 25 psi , after replacing the unit its back to normal ,why i dont know, but it eases my mined,

 

Check the oil pickup tube. If it is clogged a new oil pump would be a wise investment as it has probably been starved for oil and is now cavitated. also lose the idiot light. a guage that you can accually read is worth its weight in gold.

 

the stock gauge has no numerical numbers.

is yours after market?

 

no its not, but I'm thinking about changing all my gauges over to after market ,oil ,volts,etc... even a rpm as well.the after market stuff isnt bad looking to,I well fill alot better knowing that what I'm looking at is real [ what do you think ]

 

so where did the 25 psi reading come from?

 

Thanks for the info. Is a chemical flush the best way to clean the pickup and the screens?

 

my oil gauge reads right in the middle, so I,m guessing its 50 psi, I could be wrong,

 

a flush will help, I did mine at 120.000 mi, the engine sounded great after that.but dont do this to many times ,its bad for the seals.

 

you are just quessing what the pressure is.

flush may help but replacing screen is the answer.

once it gets clogged it needs to be replaced.

 

If you replace the clogged screen , and that was the answer, please let me know.