Oil Light stays on but lots of oil pressure

vicco27 · Jan 1, 2009

Now the rest of the story!
Christmas Eve, our daughter left her purse here when they went home. I took off after them in Cubby trying to catch them ( at times reaching over 95 MPH ) which looking back was pretty stupid. ( I finally got the purse to Vicky ) anyway on the way back and almost home I started smelling oil, then the oil light came on. I drove slowly though running a red light ( I stopped and looked both ways ) trying to get to a commercial card fuel station with lots of lights and now with a cop in hot pursuit. So I get to the station, get out apologizing to the officer but going ahead and lifting the hood and trying to figure out what is wrong. Oil all over under the hood, no oil on the dip stick, so after a little bantering with the officer he say I have enough problems and leaves. No ticket. Ok things are looking up. We ( oh ya I had called my son to bring some oil ) four quarts later dip stick says 1 pint low, so I start it and Mike watches ( split high pressure oil line to remote oil filter ) We pull high pressure line at filter adapter and and return line from filter, then loop return line back to the high pressure fitting on filter base, wa la. Start Cubby, oil light goes off and no noises so I come on home. We continue our Christmas. The day after Christmas I start Cubby and pull it around back to work on ( oil light again went off with no noises ) We try to clean up every thing and replace both remote oil filter hoses with new hose, add another quart of oil, and start Cubby ( oil light won't turn off but no noise ) We pull old spin on remote oil filter thinking something might of happened to it and I start engine ( lots of oil on pressure side ) I install new filter and start motor ( oil light stays on but no noise ) We had to drive Cubby about ten miles that night to get prescriptions. Ordered an oil pressure sending unit and replaced it tonight, ( started engine and the oil light is still on ) When looking at the old oil pressure sender it didn't look oily on the end so I blew into the mounting hole and you can hear air at the oil filler cap hole. We drove to get a pizza and there is no noise and the motor is obviously getting oil. Can some one help me figure this out? It doesn't make sense.

P.S. I also disconnected and reconnected the battery.

2001SL2 · Jan 1, 2009

extreme assumptions, not sure if they make sense...

Maybe the oil pump is damaged from lack of lubrication (i know there would be no pressure but maybe its lower than normal)

Or maybe due to the momentary lack of oil, the funnel thing in the oil pan sucked up contaminants that possibly clogged a passage, possibly affecting the reading of the new sensor (maybe that's why the old one was rather dry)

How about running a flush or a cleaner like Marvel Mystery Oil and resetting the ECU to see if something cleans up and the light clears?

brett gazdzinski · Jan 1, 2009

I would screw in a mechanical gauge and check the real oil pressure before even starting the engine again.

A number of things could have happened, none really good.

The sending unit is set to go off at under something like 10 psi!

The motor may not make any noise with no oil pressure, as its not a lifter engine, valve noise stays the same, oil pressure or not.
Other bearings wont make much noise at all as they self distruct...

You may have already killed the engine.

I dislike any sort of add on stuff to the oil system, on cars or bikes, its just another point of possible failure.

Brett

ddsmith · Jan 1, 2009

That doesn't sound very good. Low oil pressure is a killer on the main and rod bearings. It's also bad news on cam lobes. The pressure of the valve springs against the lobes creates a high load area requiring good lubrication and this area is normally the most remote in an oil system. I haven't had the pleasure of ripping apart a RAV4 engine to get a good feel for flow paths. I agree with Brett. Check the oil pressure with a mechanical gage. As an alternative, you've run it for a while in this condition. You could drain the oil and look for abnormal color. My 3000GT VR4 ate some bearings pretty bad and the oil had a gray and copper color to it from the bearing babbit being destroyed. It did have a rod knock noise that kept getting louder as I was trying to limp it home following purchase. I eventually gave up about 60 miles from home when the oil pressure light came on any time I was at idle and the noise was getting worse. I didn't want to have to replace the block along with the other stuff. Oil pressure is the telling thing though. As bearing clearances widen the oil pressure drops and you can live with somewhat reduced pressure but there is most likely some damage running that low on oil for a while.

vicco27 · Jan 2, 2009

To clarify

I was only doing 60 when I smelled oil and immediately slowed down to maybe 45 before the oil light came on. I almost coasted off the freeway to the light and then kept the RPMs below 1500 to the card lock. After talking it over we only put 3.5 quarts of oil in to get to full on the dip stick. When I started it to find the leak the light was flickering as I shut the motor off. When I restarted it after looping the remote oil hoses the light went right out and stayed out all the way home at normal RPMs. When I restarted it a day and a half later to replace the oil hoses and pressure wash it the light went right out. AFTER pressure washing the under hood, motor etc and replacing the hoses, still with the old oil filter on is when the light stayed on. Thinking something was wrong with the old oil filter I took it off. While off I restarted the motor for a millisecond to see if there was oil that far. There was lots of oil coming from the oil pump and out the pressure side of the remote oil filter adapter. I rebooted the ECU at this point by disconnecting the battery for about 30 seconds and then reconnecting it. Oil light is still on. I then replaced the oil pressure sending unit and the light is still on. However I didn't think to reset the ECU again. I will do that tomorrow. By the way I think that the extra quart and a half of oil that makes up the remote system may be both a detriment and an asset. A detriment because I was cheap and didn't put new hoses on a used off Ebay kit. Possibly an asset if I didn't burn the engine up because of the extra oil which was the main reason I put it on in the first place.

nobull1 · Jan 2, 2009

Did you try looping the remote filter hoses together?

brett gazdzinski · Jan 2, 2009

On almost every car, the oil pressure warning light has nothing to do with the ecu.
Try grounding and ungrounding the wire that goes to the oil pressure sending unit, and see if the light goes on and off like it should.
Key on, engine not running...

When fooling with hoses and so on, its not unusual for dirt or rubber from the hoses to get into the oil system.
That could get into something and cause problems, but its not likely.

Maybe the wire is broken inside the insulation or something...

Brett

Oil Light stays on but lots of oil pressure

vicco27

2001SL2

brett gazdzinski

ddsmith

vicco27

nobull1

brett gazdzinski

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