Oil pressure light came on randomly - twice. Then never again..?

Hi all! First time poster from Maine here, my apologies if this is already a thread on this (I didn’t find one, but there are a ton to weed through).

Last night, we were driving my 2001 Tacoma, V6, 4x4, approx 250k, automatic, and the oil pressure light came on and went off within 20 seconds. A minute or two later, as we were discussing what to do, we were going about 55mph up a hill, after driving for about 35 minutes, the light came on again.

The truck acts completely normal on all occasions. (Minus the mysterious vibration between 48-52 mph, which no one has been able to figure out, but that’s for another thread)

Found a place to pull over at the top of the hill (about a minute or less). Turned off the engine, checked for visual signs of leaks, etc., level was where it should be. No engine codes (I have a FIXD scan thing that stays plugged in).

Turned on the truck and there was no light. We drove home (hour and a half) with no issues.

Over the last year I’ve had done a few things to it:
- timing belt (that was embarrassing, but I didn’t know it had a belt)
- water pump
- MAF sensor
- battery
- oil changes
- suspension, which I know has nothing to do with the oil but wanted to give props to Toyota - the struts and ball joints were original!

I have an oil pressure gauge which I’ll attach and read today. I am hoping it is something simple, and was wondering if anyone else has seen this happen?

Thanks!
C

 

By oil pressure light do you mean the little oil can?

If your oil level is good, then there is clearly something else that is worn out:
Oil pump
Temp change affecting oil viscosity
Oil pressure sensor
Worn engine internals

Others will chime in with how to check each of these things but it’s a good place to start looking.

 

Start with your oil pressure gauge and go from there. If you are lucky, you just have a bad sensor or sensor wiring. Check pressure when oil is hot.

 

Yes, the red oil can light (that is the pressure light, right?).
Yes, just those two times and then never again. Of course, it just happened last night so I’ve only driven home since then.

Thank you, I sure hope it is something simple. I’d rather troubleshoot ASAP then wait for something bad to happen.

 

I wouldn't worry too much about it, unless it's coming on during flat driving. Different scenario may trigger the light.

As you mention, hill climb (depends on how steep) and how long you were driving to reach the top. Also, hi rpm with a steep inclined pushing oil reserve in the pan toward the back, away from the sump.

If this is happening while in town driving, might be a defective oil pressure switch or oil pump. If you know the level is correct, drive it and go from there.

 

Sounds like you’re on the right track correct oil level when cold and level, check oil pressure when hot, possible bad switch? I’ll throw this out there- if oil pressure switch is downstream of oil filter then possible plugged filter. When was your last oil change, is the oil level overfilled- can cause foaming=cavitation=oil pump not pump so good.

 

That makes sense.

I should mention too that I wasn’t driving but was a passenger - I hardly ever let anyone else drive it, and I baby it when I’m going up hills, etc.
Last night she may have been working a little harder than usual.

 

No discussion needed. Turn the engine off immediately. 20 seconds of no oil pressure is enough to damage the engine. As it turns out it could have been (and I hope it was) a false alarm because of a bad sensor.

A long time ago a friend of mine left his house and the oil light came on. He figured he'd drive 2 miles to the nearest gas station to buy some oil. The engine died 1000 feet down the road, of course!

 

It was changed about 2 months ago - maybe 1500 miles. The level is spot on and I’m not sure if it is below the filter or not. I’m still learning!

 

Oh no! That’s awful!

It was litteraly just a few seconds before we turned it off. If we had stopped where we were, we would have been creamed by the trucks behind us. But I totally hear you, and if we were in a safe spot we would have stopped there. I’d never keep driving it with the light on. I love it too much!

 

If you can check the pressure both at inlet and outlet of filter. If the test port is downstream of filter and you get a low reading I would suggest replacing filter and recheck. Now if the filter is plugged then that might be another issue. If test port is inlet of filter and pressure is good then possibly replace switch. My experience with switches/ sensors going bad is that they don’t necessarily fail right a way but have intermittent symptoms before ultimate failure. My wife’s care had a cam position sensor go out recently and that’s how it acted- intermittent

 

I had a car that did this. After finding the sensor was fine, changed the oil pump and that fixed it. Easy enough on a civic but if you have 4x4, there's lots of shit in the way and that pan isn't dropping down.

 

1/ Oil pressure sensor bad, seen a bunch of em but these were not toyotas.
2/ Top part of engine sludged so the oil not draining back fast enough.
3/ Bad main bearings but you maybe should of heard this symptom at idle.

Get you a manual guage and put it on under the hood to find out for sure, temporarily.

 

Really easy on a 22RE but no experience with this generation of 4 cyl.

 

Bad bearing and mystery vibration??? Maybe??? Let’s hope that isn’t it.

 

I don’t think the two are connected. I’m pretty sure that I have a bent rim. The drivers side of the bed vibrates at a certain speed, but nothing in the front.

 

for peace of mind I would have a new oil pressure switch installed, if it comes back on then investigate.

I switched from dino oil to Penzoil's full synthetic and Wix filters on my Ranger 4.0 and my Crown Vic 4.6 and on both vehicles on cold start up with air temps below 50, the oil light would come on. Shut both off and drove another vehicle and came back at noon. With the higher air temp both got oil pressure immediately. Next morning, the same thing. I stopped by my local O Reillys where I bought the filters and mentioned it to the store manager and he gave me a Bosch filter for the Crown Vic, easier to change than the 4.0 in the Ranger and that solved that one, the Ranger required a OP switch. I, the store manager nor Wix has an explanation... just a coincidence I guess.

 

Me again... After almost a year of no issues, the darn light came on again. As I pulled over it went off. I got to my driveway and it came back on.

There is oil in it.

Brought it to the mechanic, he did an oil/filter change (it was overdue for a change, but I always make sure there is oil in it). The light went off when he started it up.
Then he tested the pressure (took off the switch to do so) and got
4. @idle
"almost a little drop in pressure" @3,000rpm

He is getting another gauge because his doesn't show the exact psi, I guess it goes from 1-10. He wants me to drive it locally for a few days to see if it comes back on and do some internet research.

There is no noise coming from the engine, no knocking or anything like that.

Any thoughts on what could cause a pressure drop at higher rpms when there are no other symptoms?

Thank you!

 

Maybe the pressure switch is faulty, gunked up, so not switching on/off at the correct pressure.

I'm only speculating about the pressure drop at higher rpm. It could be so much oil is pumped to the top of the engine there isn't enough time for it to drain back down, so the level is low. That shouldn't happen unless you are using a thicker oil or the drain passages are blocked. My other theory is the Bernoulli effect as oil gets pumped past the pressure switch location faster the pressure actually drops.

 

Is the switch different than the sensor or sending unit? (sorry, I won't know till I ask!)