Hi folks, my first post here.

I have an '89 F150 that has had a steady decline in oil pressure.
I checked it today, it was a quart low, so I added oil. There was no change in the pressure.

A mechanic who works for a Toyota dealership told me to switch to a Toyota filter. Same threads as Ford, but being smaller, it would boost oil pressure. Can I do this, and will it help?

What exactly causes the drop in oil pressure? Bad oil pump? Dying engine? The engine's a rebuild that has 112K miles on it. It was rebuilt at approximatley 84K.

I only paid $1,500 for the truck, I'd hate to sink another $2K in it having a new/rebuilt engine put in.

FJ

 

If you have the stock oil pressure gauge, you do not have an oil pressure problem, you have a wiring problem. Since 1987, Ford has used an on-off idiot light sender with the gauge. It should read exactly half or zero. DO NOT spend any money on engine work until you are sure about the real oil pressure. Install a real ('86 or earlier) sender or a mechanical gauge first.

A smaller filter would do nothing because the filter is ahead of the bearings. If anything it could restrict oil flow, but the bypass valve would just open, allowing oil to pass unfiltered. I question why a mechanic would not understand that.

Jim

 

Yeah, my gauge is one of the needle jobs that has "L" on the left, "H" on the right, and "NORMAL" in the center.

It was reading in the "NO" of Normal, but now it's slmost down to the "L". A little right of "L" when driving, dips down to the "L" when stopped at idle.

How do I go about replacing the sending unit?

FJ

 

You are listening to a Toy mechanic!? Hmmm. First my opinion of factory mechanics is that many do not really understand what they are doing, they just follow a procedure until they finally "fix" the problem. If you find a mechanic who understands why he is doing something stick with him. Next, what does a toy specialist really know about Fords?

Anyway, the other guy is right, the filter would not have any real benifit other than it may restrict the oil flow and it may clog up sooner, both are bad.

You may have a pump that was not rebuilt or new, has a weak spring, or a loose pickup. You might also have unusual engine wear in the bearings(cam and crank). Or you may have some bad gaskets(usually head). These are all potential problems if the rebuilder was an el cheapo or low quality shop that uses cheap parts or reuses worn parts.

But first check the pressure with a real gauge and then you can start to figure out where the real problem is.

Good Luck,

Jim Henderson

 

Another possibility:

Depending on historic oil change frequency, the oil pickup screen could be partially clogged. Mine was half clogged around 65,000 miles.

I have a '95 with the idiot gauge. I have had problems with the sender, which was replaced once. Sometimes the pressure reads low. I fiddle with the connection and it gets better, then drops again. Seems to be a loose fit. Now I have aluminum foil wrapped around the terminal, but would like to find a conductive paste to put inside the wire boot for a better connection. Guess I should try a new sender.

BTW: I thought switching to the old gauge-type sender would not work unless you put a jumper wire across the resistor on the back of the gauge. At least that's what I recall. Somewhere on the net is an article on how do do it.