Low oil pressure light help

I need help with my 1996 Tacoma 3.4. After driving my truck for 30+ min the oil light flickers on during low rpm but goes away with higher rpm’s.

I have done a ton of work on this engine and refuse to let her die. I did an oil change, dropped the oil pan and replaced the gasket, cleaned the oil pump screen which didn’t solve the issue. The last step I could think would be to replace the oil pump but hoping someone has something else to try

Any recommendations on where to go from here would be super helpful.

 

What about changing the oil pressure switch before changing the pump? Might be faulty and original.

 

I'd verify you have low pressure with a mechanical gauge. From there you can try an oil pump or you can pull the pan and try to pull a rod cap and I'd do a main cap too. Get some plasti gauge and measure bearing clearance.

 

Gauge first, but it sounds like it has an internal leak or excessive clearance somewhere.

I usually say its a plugged pickup but you've already taken care of that.

 

I ordered an oil pressure sensor in hopes that’s it. I will go rent an oil pressure tester to see what the pressure is. What would be the range I am looking for. I put some Lucas oil stabilizer “fixed” the issue immediately but haven’t driven the truck for much time after.

My tacoma has 220k miles with recently replaced vacuum hoses, head gasket, water pump, thermostat, belts, cv axles, tie rods, rack and pinion, New gaskets in pretty much every place you can put on in the engine. While tearing down to replace the head gaskets completely gutted and cleaned the grime from all the places and very meticulous in putting things back exactly where I got them from. When I took the heads off the block I got them planed down. All that a bunch of cosmetic stuff and a beautiful fresh coat of paint.

I have a place in town that sells a new oil pump for my Tacoma but don’t want to tear apart the front of the engine again without knowing for sure the oil pump is bad. I have never had an oil pump slowly go bad and this has been getting progressively worse over the past year. I’m still getting oil to the top of my engine when I took the valve cover off and ran the engine. (Big mess) When I pulled the oil pan no metal in the pan or on the strainer.

 

While getting the oil pan out I was forced to drop the transmission. Great time to replace the warn cv axles. When putting the transmission back into place after putting the oil pan back the transmission dropped on my head and caused some mild trauma. Definitely hoping to avoid ever taking the transmission down again. In the photo below you can see some dirt and debris on the oil pick up tube which nothing was magnetic or metal. I cleaned it off completely but still having the issue.

 

sweetest looking '96 taco

 

An inspection of the pickup assembly would have been in order too. Welds crack, gaskets get hard and crack. Any place where it can suck air it will suck air. In my high mileage Nissan D21's, 300k+ I would run straight 50w and let it warm up before I would put any sort of rpm into the motor. Those old hardbodys with the twin plug 4 cyl motor, IMHO motor wise, are just a smidge better than a Tacoma.

 

So I replaced the oil pressure sensor and still getting the same oil pressure light. The light flickers and isn’t completely solid and again it goes away with an increase in rpm’s but comes back on when the rpm’s decrease

 

At what RPM is the engine idling at?

And If I ripped the engine down that far for a oil pressure issue, I'd toss in a new pump just for good measure. Heck, after all you did already, I don't know why you didn't anyways.

Why did you redo the head gasket? Blown? Was there ANY coolant in the oil? If so, it's pretty bad ju ju and could be contributing to your issue.

 

I’m kicking myself so hard for not. I was right there but didn’t have the issue when I replaced the head gasket so I thought why replace it if it isn’t broke. Definitely kicking my self for it.

Idel RPMs are like 800-1000 when in park with no light. In drive or reverse RPMs drop to 600-750 when stopped where the light flickers on.

I had some mild overheating with a light smoke in the exhaust. Which someone pointed to probably a leaky head gasket. No milkshake color oil before I replaced the head gasket but exhaust bubbles in antifreeze were noted. I tore it apart on the hunch and noticed just a small tear in one of the head gaskets. That was over a year ago and haven’t had any issues related to that. I had the heads checked for warping just because it did slightly overheat which the guy said both the heads and the blocks were totally fine.

The truck is currently put back together and I still use it as a daily driver. Just worried about doing damage going for longer drives

 

I would honestly replace the oil pump if everything else checks out OK.

 

Put a mechanical gauge in it and see what your oil pressure really is before you toss parts at it. I wouldn't run the engine until you do.

 

Ditto, quit guessing and find out for sure what the pressure is.

 

So ran the oil pressure test and the PSI at 3000 RPMs is around 25 psi and idle in park is around 7 psi. During drive/reverse is 5-7 psi

 

Seems low at 3K, pretty sure the factory manual says it should be 40-70 but I would need to look, I have it around if you want me to look it up.

 

I have the manual and it’s definitely running low at 3000 rpm’s but the idle rpm’s surprised me. What could be the cause of low psi at 3000 rpm’s? What would be next steps/advice going forward?

 

overlarge clearances would be my guess

 

Yeah, probably shot bearings, but you may luck out that it's the pump. I wouldn't hold my breath though.

 

What weight oil do you run?