Oil light at low rpms!???!

Just did a rebuild on my 97 3rz m/t not long ago. The oil light is on at idle and cruising but if I’m at higher rpms it slowly fades away but then comes back. Sending unit is new and fresh (5w30)oil with puralator filter. Could this be a faulty oil pressure switch? The wiring is good on the pressure switch and truck drives great! Thought about maybe changing to thicker oil and Toyota brand filter. Thoughts? Thanks in advanced!

 

Could be a switch. Might be a weak pump or excessive clearances in some bearings.

put a real gauge on it and see what it says

 

Check the oil pump.

 

Sounds like an unsealed oil pick up tube or pump to me if it was rebuilt.

May want to pull your pan and check your pickup O-ring and pump seals, you might have broken your pick up tube also.

 

When in doubt Install a manual oil pressure gauge and see what you have for real.

Before pulling engine parts apart.

 

I installed a new pick up tube gasket and oil pump not long ago during the rebuild. Hoping it is just the switch. I will manually check oil pressure and see what I get. Oil pump is OEM

 

Manual gauge and get rid of that crap filter. Put on a Toyota filter.

 

Do you know the proper thread for the oil pressure gauge needed and what the oil pressure should be?

 

Do you know the proper thread for the oil pressure gauge needed and what the oil pressure should be?

 

10lbs/1000rpm is the traditional rule of thumb for safe pressure. but the toyota spec is lower than that:
http://www.markofshame.com/fsm/03_Tacoma/Repair_Manual/03tacoma/ss/lu2rzfe3/serdat.pdf

You should be able to tee into the oil pressure switch threads with simple brass fittings. Just take the switch out and head to the hardware store

 

Wow, just saw a thread on this a few weeks back. Should be on TW and the correct reading.

 

This kit has a bunch of different fittings/adapters and is only $30

 

Did you verify ALL bottom end tolerances with plastigauge?

 

Would using different weight oil help this? I live in Tennessee so don’t really get too cold here. 90 degrees right now. I currently have Castrol synthetic blend 5w30 in it

 

It may change the oil pressure, but fixing the problem is better than trying to pour your way out of it.

 

Sorry I have a whole drawer full of fittings I just grab a hand full most often a Metric adapter to Pipe thread.

oil pressure at idle 600 rpm 4.3 psi minimum

above 3000rpm a low of 36 psi to 72 psi

How long have you been driving it??

A serious problem most likely would have had a major failure.

Are you sure the oil light circuit is not being lite up by something grounding back into the circuit??

 

it isn’t my daily. I’ve driven it maybe 100 miles or less after the rebuild and the light never came on. Just started recently. I have drove it around town a few times since the light has showed up randomly and it hasn’t blown up LOL. I thought that same thing too about the grounding or wiring. The seatbelt light right beside it randomly flashes. Even when the belt is buckled. Another reason I think this is because the truck was in a driveway when a house caught fire and melted the windshield, fender, hood(which all has been replaced). So that has crossed my mind. Just strange it didn’t do it at first but now all the sudden is

 

how could I trace it from being lit up by something else grounding or whatever?

 

It can be a royal pain but you need to look at circuits that ground to the same point.

like you said the seat belt light also flickers .

As the oil pressure switch grounds via the block any thing else having a poor ground into the block can ground back through the oil pressure switch.

A bad switch could act that way as well.

 

I will be changing oil/filter/switch. What weight oil do you recommend? Currently 5w30