oil pressure drops - Ford Forums

jmehan · 09-08-2009, 09:56

85 f150 302. The engine has about 31,000 miles on it. It just started loosing oil pressure after it warms up. I removed the sending unit and installed a pressure guage. At start the guage reads 50 pounds. After driving 2 miles it drops to 40 pounds. Driving 10 miles it drops to 25 pounds while driving at highway speed and idles at 10 pounds. I did notice that when it is at 25 pounds and I let off the gas the pressure will raise to 35 and then go back down again. I checked for oil leaks and found none.

Any ideas?

**rtg143** · 09-08-2009, 10:11

I bought an E150 several years ago and the oil pressure would drop when cruising at highway speeds. I took the oil pan off and found the pickup screen for the oil pump plugged with sludge. Evidently the previous owner didn't change the oil regularly. I cleaned it, put it back together, ran some engine cleaner through it and drove it another 30k miles before I sold it. The oil pressure stayed up then. Not sure if this is your situation or not.

Steve83 · 09-10-2009, 11:20

An '85 with only 31K??? How about 231K, or 310K?

How much oil is in it? What weight? How many miles on the oil? How many on the PCV valve & breather? I agree on the sludge - the easiest way to check is to pull the engine to drop the pan.