miwise

I have low oil pressure and I know that both valve covers leak some oil. The drivers side valve cover leaks a good bit, but not enough to affect oil levels. It is a 351 Windsor. Can this cause my oil pressure to be low at idle but OK at cruising speed?

unclebubbles

Not unless it runs out of oil, or the oil return holes in the heads are partially clogged, not letting the oil return to the pan fast enuff. Could be worn bearings, oil pump, partially clogged pick up screen, or a number of other things. Put a manual gauge on it to verify the readings. Do you hear any noise/rattling/knocking when you first start it in the morning? If its not rattling , and the pressures ok at cruise rpm, and not dropping to zero at idle, you can probably get alot more service before it needs serious attention. Just keep good clean oil in it, and maybe add a little stp. Lots of opinions about stp, but i like it and use it. Good luck.
Later
Ed

miwise

I don't really hear any knocking, but it does make a ticking sound when at idle. At least I think it sounds more like a tick. (about 4 or so ticks per second) Thanks for the advice. I'm going to let my mechanic look at it as soon as he gets back from off shore. Thanks!

ModMech

NO.

You stated that the level remains ok, so absolutely not.

Depending on what year truck you have, your oil pressure "gauge" is NOT a gauge at all, but a switch activated indicator. 0 - 6 PSI = 0%, 6 - 100 PSI = ~45% of scale.

It is VERY common for the switch to start to go bad and intermittantly cause the needle to go to "zero" at idle.

Ford started using this system in the mid '80s, and by '88 it was on everything they sold.

unclebubbles

On older vehicles, Ford and other mfgs. , used a oil pressure sending unit as opposed to the oil pressure switch, for the dash gauge. Some may still use it. This sending unit is a variable resistor controlled by the oil pressure, and inversely proportional to it. (oil pressure goes up, resistance goes down and vice-versa) It controlled the current going to the gauge and gave a reading that would vary with oil pressure, as opposed to being on or off like the oil pressure switch. They were fairly accurate, but like any electrical device, subject to failure, and false readings. I dont know what year they stopped using them, i have an 85 and an 88 here that both have this system. The best system of course is a manual gauge, and it is always a good idea to check your pressure with one to verify a problem. You can make one up for a few dollars, and you can use it for other test purposes with a few extra fittings.(fuel pressure, cooling system..ect.) Good luck.
Later
Ed