My new to me 88 4runner (3.0) is running good with no other issues other than low oil pressure once its up to temp. At initial startup the oil pressure goes up to the middle mark then slowly falls as the engine warms up. It will still climb to roughly 1/8 the gauge at 3000 rpm. I swapped sending units with my 84, no change and put some 40 weight in. That increased the initial pressure but no change after warmup. The truck has 268000 miles and runs strong without any weird noises. My next step it to drop the oil pan to inspect the screen and pressure relief Valve. The fsm shows that I should be able to get it after dropping the pan. Anyone have any experience on this? Might change rod and main bearings while I'm in it (depending on what I find). Reminder I have 7" of lift which allows plenty of clearance with the front diff. Any tips or pointers are appreciated. Thanks

 

Also no oil in coolant. No coolant in oil. No smoke! Unknown history as I've only owned it a week or two. The oil pan has been off in the past from the sealant appearance.

 

There is a wire connector plug behind the alternator, Check it out and make sure no corrotion or freyed wire.

 

There's no way to reliably check the oil pressure with the factory gauge. you need to get a verified gauge to see if you have good oil pressure. Like Punchy said, could be corrosion or bad connection on the oil pressure switch wiring.

 

Thanks for the feedback!! I am waiting for graingers to deliver a 1/8" bsp to 1/8" npt nipple. The rest of the plumbing is ready to be hooked up. Cross your fingers, if this doesn't work I'll be dropping the pan

 

Conclusion: 85 psi on startup. 34 after warm at idle!!! Mechanical gauge verified. This saves me a headache. Thanks for the direction

 

Cool--congratulations! An engine requires 10 psi per 1000 rpm for sufficient oil flow/protection.

 

The 3VZE motor by design, normally has low oil pressure to begin with.
Combine that with a low quality gauge on the dashboard, and it can start you worrying needlessly.
It is an overhead cam motor, and the valve lash is controlled by shims.
This does away with hydraulic lifters, and the oil pressure needed to operate them.
It is a simplistic design that has its pros, and cons.
Run a 15/50 oil if you want a higher needle on the gauge, but it really isn't necessary.

Art.