1999 Exp XLT 5.4L 2WD Oil Pump Failing?

[mjbtn]

Hello to All,

I am an IT consulting professional by trade with some modest automotive repair and tooling experience.

I have a 99 Exp XLT 5.4L 2WD unit that has (I think I have narrowed it down) a failing/failed/clogged oil pump (after much observation and forum research).

The cPanel® has 170,000+ miles and started to have the oil pressure guage drop off and warning light coming on and off abruptly when the oil level got below a certain point. I would add a quart of oil or so (back to "full") and the behavior would go away. The engine burns oil but there is no visible tell-tale smoke in the exhaust and no visible leaks under the vehicle where it is parked at night. I had always attributed this to just the "normal" behavior for this engine as it has aged.

Then, recently, the oil guage fell off abruptly and the oil light came on and a VERY perceived knocking in the lifters (I assume) would simultaneously become evident. The engine has long had a slight knock, but, never had a loss of power and I assumed 87 octane and just aging. But this new behavior was abrupt. I added oil and verified the level and that was good. Now, when I start the engine, it starts up normal and idles fine, but, shortly thereafter (with the oil level good), the oil light comes on, the guage falls and the knocking commences. I have not been driving it except gradually up and down the driveway to observe the behavior.

after MUCH reading, and all things considered, it appears that the oil pump could indeed be suspect. what makes me further think this is that there are moments that the oil light will go off and the guage returns to its nominal position and the knocking abruptly stops and again idles fine. It seems to manifest the problem more as I begin to apply the gas and rev the engine up. It will often start to rev up normally and then the light comes on and knocking commences.

So, am I on track with this??? The truck has been parked in the driveway ever since as we have a 3rd car. I am now getting around to trying to get this looked at. But, I assume I will have to have it towed if I take it to a shop. So, I am trying to do some homework.

Is this a costly repair??? What else might it be? If the pump pick up line is clogged and the pump itself it OK, how to test and likewise, is there anything I might do to correct that situation? Is this something I could do myself or will the engine, tranny, whatever, have to be pulled out and apart to even get to where the pump can be examined?? I have read that you have to remove the timing chain and the oil pan to get at it. And, with a 9 year old, 170000+ mile vehicle, is this even worth bothering with fixing or should I "scrap" it (Kelly BB indicates about $1500 for this)?

Any input would be greatly appreciated. I know throwing enough $$$ at it will fix it, but, with gas $ and the economy the way it is, I simply need to be smarter about spending $ in general these days.

Thanks very much!!

[bradrhale]

how often did you have to add oil to it and how much?? have you checked the fluid level after several hours of sitting to verify that the oil is returning to pan like it should?? the knock unfortunately might be a worn part and will never cease even though you correct your oiling problem. cant not tell you how much this would be to fix there is no telling what is giving or already gave up.

[mjbtn]

Normally, it only needed 1 quart added once every 8-12 weeks. also, when the oil guage is "normal" the engine runs fine! now, when the guage drops and the oil light comes on substantial knocking develops. and, as it has done, if it happens that the "condition" dimishes, the oil light goes off, the guage returns to normal and the substantial ping (as well as some loss of engine power) vanishes. So, there is a direct correlation to the guage dropping off, the oil light coming on, and the substantial pinging! this is why i started to narrow in on the oil pump (or a related choking or blockage); the oil pressure is really fluctuating abruptly.

BTW, one responder on another forum recommended running "engine flush" (oil additive??) and the change the oil and filter as the filter may be bad or if marginally improved that I might have sludge at the bottom of the oil pan restricting flow into the pump. I did have an oil and filter change at a Halvoline place only a few weeks before all this started. I have no idea what kind of filter they used, but, I suppose it is conceivable the filter might be a dud. Another guys suggested an oil and filter change but be certain to use a Motorcraft filter.

oh yeah, the last time i added oil, i did in fact do just as you suggested and let the engine sit for a few hours and then checked the level and it was full on the dip.

[bradrhale]

you might have it nailed as a weak oil pump. with your problems, i would be nervous about using a engine flush. that stuff is designed to break down deposits. well, if you break them down with a weak pump, you are headed for more headache. i might have suggested a weak oil sending unit but one that is broken or malfunctioning would lead to the engine to kill the ignition, i think. but you are also getting a knocking so that throws that idea out the window. i believe there is a way to test oil pressure but not sure how to do that on the 5.4 liter. hopefully, someone here might know more about it than me.

[javrey]

company had older ford that would lose oil pressure and when let it sit and restart after a little bit it would have oil pressure and it was sludge build up in oil pan and the pump would suked it up lose pressure. changed oil pump and cleaned oil pan ran great and still running