The Ford Barn

mcgarrett · 08-15-2020, 03:42 PM

At engine startup on my '40 Ford with stock engine, my oil pressure gauge reads 45+ lbs of pressure on the factory gauge and has done this for quite a few years. After driving for 20-30 minutes and the oil is up to temperature the gauge reads around 10 lbs going down the road and maybe 5 lbs. at idle. My oil pressure sending unit is an old one; maybe the original.

My questions are:
- Is the sending unit malfunctioning perhaps due to age?
- Is it possibly a weak pressure relief spring playing tricks when the oil gets hot?
- Is it a faulty gauge? (it's old too)
...or a combination of the above?
I want to make sure I am diagnosing my problem before I order and replace a part unnecessarily.

08-15-2020, 03:42 PM	#1
mcgarrett Senior Member Join Date: Dec 2013 Location: Corsicana, Texas Posts: 1,306	Oil pressure drop At engine startup on my '40 Ford with stock engine, my oil pressure gauge reads 45+ lbs of pressure on the factory gauge and has done this for quite a few years. After driving for 20-30 minutes and the oil is up to temperature the gauge reads around 10 lbs going down the road and maybe 5 lbs. at idle. My oil pressure sending unit is an old one; maybe the original. My questions are: - Is the sending unit malfunctioning perhaps due to age? - Is it possibly a weak pressure relief spring playing tricks when the oil gets hot? - Is it a faulty gauge? (it's old too) ...or a combination of the above? I want to make sure I am diagnosing my problem before I order and replace a part unnecessarily.