I had an oil leak in my 1990 Ford F150 with the 5.0 engine A/T. I took it to the shop and they replaced the oil pan gasket about a year ago. Truck had no leak until last month and it started leaking bad. The oil pressure gauge sometimes when you are at a idle will jump up and down. From talking to a freind he said it may be the oil sending unit / sensor because of the gauge jumping up and down and the amount of oil it is leaking, about a quart in 500 miles. I have looked for the sending unit and can't find it. I asked at autoparts store and they said it should be in the block on the drivers side near the oil filter. Do anyone know were to locate the sending unit or have any other suggestions. Thanks for any help or suggestions.

 

The parts store was correct. On the block, to the left of the oil filter if you are looking at it from the drivers side.

 

It's between the PS pump & the oil filter, recessed deep against the timing cover, and it takes a big socket to get it out.

But IMO, it's not worth replacing. It's not really a pressure sender - it's a 6psi switch, and there's a resistor on the instrument cluster that causes the needle to go to the center & stay there as long as you have more than 6psi.

For a few bucks more, you can install the older (pre-'87) pressure sender, put a jumper across the resistor, and have your gauge actually indicate changes in oil pressure. You'll also need ~$6 worth of plumbing since the older sender is too big to be recessed in there.

. .

 

Could this be where the oil is leaking from? Do they usually leak? If so do they leak alot?

 

Yes, they can leak.

 

Anything that has oil in it can leak. Oil pans on these trucks are known to rust out and start dripping, and replacement is the only real fix.

If you have trouble locating the drip, clean as much oil off the engine as possible, and buy a can of that white foot powder spray. Spray it all over the bottom of the motor and any place you suspect may be leaking. Come back in the morning and a drip trail will be very obvious. Then just wash away the powder with a garden hose.

 

Mine was leaking real bad and I cound't find it for a few days.I would clean off the whole engine then drive somewhere and stop and look for leak.I thought it was the rear main seal.Finally one day I cleaned the engine,started it and crawled under my truck while it was running.Guess what .Oil was blowing out of oil pressure sending unit.Got me a new one for $10.

 

billyf150, how did you get the sending unit off. A 1" deep well is to small and a 1 1/16" is to large. I own a '94 and need to get mine off. Are these sending units metric?

Thanks

 

It's a perfect 1 1/16", but you have to use a 6-point socket.

 

Indeed - I had to use a 1 1/16" 6-point DEEP socket to get at it, for anyone about to buy a socket.

Just changed my oil pressure sensor out on my 302 - it was leaking like crazy, but oil pressure was showing fine. I held off on replacing it for this reason.

I finally tracked down the leak with some UV dye. Once I spotted it, it was more obvious. With the engine running, I could see it leaking (gushing) while standing on the drivers side looking at the oil filter and timing cover. I still can't believe that it was the source of all that oil.

It's nice to have a truck that doesn't spew liquid dinosaur all over the parking lot.

 

the part store has a special socket you can use. It cost about as much as the part but it is so much easier and faster if you get the socket