[Torque454]

OK so I bought this 87 F-150 about a month and a half ago and it is having strange issues with the oil pressure. Most of the time its fine, while cold the needle is about half way between low and high. Pretty normal. After the engine warms up, its on the low side of the scale, but still within the "normal" range indicated by the gauge. This is with the engine fully up to temp.

Now here's where it gets weird. I can drive across town and back about 7 miles each way and the pressure is as described above. But get the truck out on the highway for a while, or drive across town and back twice, etc, it will usually (but not always) lose ALL oil pressure at idle. Might be some light ticking in the engine (not sure tho, its certainly not very loud like id expect if there was no pressure). Does this sound like bearings? And if so, why doesn't it do it all the time when its up to normal operating temp? Also it may not instantly lose all pressure, the gauge flutters for a second from about 1/4 way up all the way back down to zero and then it goes to zero and the engine light comes on. It does "sometimes" flutter the gauge at other times without the engine going to zero pressure.

I feel it is behaving rather strangely. Oil filter is a motorcraft filter. Miles on the truck shows 24k, but was told it was 124k. Not sure what weight of oil is in the engine right now, but i have some 10-40 to change it with as well as two bottles of STP.

Speaking of STP, it has two bottles of STP in it now, it did improve the situation some when i added them, but still acts up.

What do you guys think it sounds like?

[DoubleVision]

I'd replace the sending unit.

[richard stewart 3rd]

Hi
First thing Id do is replace the sending unit. If that didn't change anything, I'd suspect the bearings have excessive clearance.
Rich
PS I realy think it's bearing clearance, espechaly with all that stp in there.

[T-bucket23]

Sounds like a partially plugged up pickup tube. Fords are famous for this. I bet as you drive is is plugging up and when you park it the crap falls off. If it is ticking when the gauge is low I would guess the gauge is working.

[68NovaSS]

Whats the oil level, low or overfilled?

[S10 Racer]

Originally Posted by T-bucket23

Sounds like a partially plugged up pickup tube. Fords are famous for this. I bet as you drive is is plugging up and when you park it the crap falls off. If it is ticking when the gauge is low I would guess the gauge is working.

I totally agree with this, I have found this to be an issue with an old Lincoln my wife had. I just dropped the pan and pulled the pickup tube out and cleaned it. Fine after that.

[4 Jaw Chuck]

Might want to check the oil pressure sending unit connection before you take anything apart, it's only a push on connector and they corrode and get loose.

[T-bucket23]

Originally Posted by 4 Jaw Chuck

Might want to check the oil pressure sending unit connection before you take anything apart, it's only a push on connector and they corrode and get loose.

A bad connection on the sender is not going to make the lifters click. This is why I don't believe it is a gauge issue. He stated when the gauge goes low it makes noise as well.