91 explorer oil pressure low

One thing that can cause JUST that: if the oil pan has sludge built up in it, the oil pump will suck it up to the oil pump pickup screen as you drive, stop flow of oil thru the screen, & starve the bearings, lifters, et al from receiving oil. When you stop the engine, this pulling force stops, the sludge drops back to the bottom of the pan, and you can restart & go a little ways until it again pulls the sludge onto the screen. Most people drop the oil pan, remove the pickup screen & oil pump, clean all well, and replace pump while in there. If the pan is a high-dollar removal job, you might want to try a much, much cheaper--yet quite effective--procedure. Leave out/change the obvious & email samdanielsatspamcharterdotnet . Luck to you, sdlomi2

If I had to hazard a guess, I'd say that your engine is all full of sludge and gunk and that all the oil is pooling in your heads when you're driving. Has this engine seen regular oil changes? Might need to be torn down for investigation, although you might be able to get by with just pulling the valve covers and cleaning the drain holes. I would definitely follow up with some kind of cleaning regimen, be it an actual treatment (I've heard good things about Auto-RX, gimmicky as it sounds) or just regular changes with a Diesel-rated oil like Rotella or Delvac. But see also the "how long do I soak my oil pump pickup in kerosene" thread for other ideas and gotchas.

BTW, running the engine for more than a few seconds with no oil pressure isn't particularly good for it...

nate

In response to other posters suggestions about sludge, how often do you change your oil and filter and what sort of oil do you use??

Low oil pressure can be due to several things, including a failed or failing oil pump, low oil level, foaming, excessively worn bearings, and sludge or blockage.

A loose oil pump pickup can also be a PITA. (Dont remember if this is a Ford problem or is mostly GM)

Maybe, but more likely the oil pump. Drop the pan and check it.

--scott

I oil doesn't look that bad. I had tranny problems and it was parked from July last year to this past Dec when I fixed the tranny. I had changing the oil "on the list", but I guess I should have gotten to that item quicker.

Do you think I created some problems after this started happening by driving it after it developed this problem?

Any time spend under load without oil pressure is Really Bad. That said, there's really only one way to find out. I know my landlady's son ran her Nissan pickup out of oil, and drove it home a couple miles (?!?!?!?) with the oil light on, and it's still kicking. I put over three quarts in it when she told me what happened (!?!?!?!?!)

In other words, you might get lucky, you might spin a bearing next week. Don't worry about it until it happens...

nate

Most likely you collapsed the oil filter element, or you have an oil pan full of sludge particles that is blocking the pickup screen after driving for a while. When you stop, the gunk drops off the screen and you have pressure again for a while.

I'd try a new oil filter first- especially if there's a Fram on there at the moment.

Since you're hearing valve train rattles, I can pretty safely say that it isn't a bad pressure sending unit.

thanks.

Are you saying that Fram sucks? Would motorcraft be better?

Mike

Yes. Paper end-caps on the filter element, sucky anti-drainback valves, less filter media. Among other things.

Much. Motorcraft filters are my third pick, after Wix and Purolator.

I'm not the poster to whom you're replying, but you can count me in the "not a fan of the orange can" list. My specific gripe with them is the lack of a functional anti-drainback valve on MoPar slant six applications, but there's so many reasons to use a better filter. Wix is commonly acknowledged to be a good, serviceable filter with no major faults, and only costs a buck or two more. Purolator is also good, and sometimes even cheaper than Fram!

nate

All,

Here is an update on my sludge problem. I appreciate all the feedback I have received.

Here is the procedure I used:

1) drained the oil while hot, but did not change the filter 2) put the drain plug back in and filled it with a gallon of Berryman B-12 Carb Cleaner (used Berryman because on the side of the can it talked about adding 6 oz. to a cars oil for cleaning sludge) 3) let it sit for 2 days. 4) drained the cleaner. 5) filled with oil and a new Fram Filter ( used Fram because it was cheap and wasn't going to be around long ) 6) drove it for 15 minutes at @ 45 to 50 mph. ( after abut 10 min my "check engine" light came on, oil pressure was fine ) 7) drained the oil, removed the crappy Fram filter 8) new oil and Purolator filter

I have driven it twice for 15 to 20 minutes twice and it seems to run fine with good oil pressure. No "check engine" light. I don't know what that was about.