Help....I have a new 351W in my 80 F100. For the first few hundred miles, at idle, oil pressure was 25psi and about 50psi above 1500 rpm. Today the oil pressure sometimes would go up and down and when first cranked it would be 50psi....never done that before. I have an Autometer oil pressure gauge. The engine seems fine, no usual noises. Could it be the gauge or sending unit? How do I find out? I appreciate anyone's help..

 

Check for large quantities of gasoline in your crankcase.

 

That is supposed to be a good quality gauge, but you could buy a cheapie and hook it up and see if it does the same thing. A regular air pressure gauge will work temporarily too.

 

Thanks for the replies....there's no gas in the oil. How would you use a regular air pressure gauge? Thanks!

 

See what type of fitting is on the back of the gauge you have now. Some of them have a compression fitting, but this fitting screws into the gauge with pipe thread, most of the time it's 1/8 pipe. So it might be just a matter of a pipe thread adapter from the hardware store, or worst case, take your air pressure guage and find a new compression fitting for it to fit the line.

You may get away with a $3 or $4 dollar fitting instead of $16.00 for a whole different gauge.

P.S. I just re-read your post and you said something about a sending unit. I assumed your guage was mechanical with a oil tube running to the gauge. If it's electric, the air pressure gauge idea is not going to work, and you will have to buy the cheapie mechanical gauge. Also, if you do have a sending unit for a electric guage, check the wiring connections, and unscrew the sending unit and make sure the hole in the unit is not clogged. A lot of them have a tiny hole that is easily clogged with sludge and carbon.

 

Yes, its electric. I'm going to remove the sending unit and check it and the connections. I definitely want to work out something with a mechanical gauge, but first I want to determine if its a gauge or engine problem. I'm hoping the teflon tape is the issue. Thanks for your help....

 

Okay, I removed all the teflon tape and put new on, but leaving some room to make sure it grounds okay. Nothing changed. Still iratic, but I did notice its not as irratic when the truck is sitting still? Does that make sense? I guess my next step is to get a mechanical gauge and see actually what the oil pressure is?