I just installed a rebuilt long block 3vze in a 95 4runner
. Sounds good but the oil pressure is not good. Cold it reads about 50 pounds at idle. However, as it warms up it drops to ONE pound at idle and 11 pounds at 2500 rpm. All readings performed with a calibrated mechanical gage.

Did I get a bad new oil pump?
Are oil return ports blocked?
Is it an issue with the oil pick up tube?
Is it an issue with the screen blocked?

I do noticed a signficant amount of oil in puddles when viewing thru the oil fill cap when the engine is warm and idling.

I need some good ideas on how to best identify the root cause before I start removing parts.

Thanks

 

If you installed the motor you self you may have forgotten or put in wrong the oil pressure regulators.... i foget how man if just one or not it has but that most likely the prob its not leaking is it? What about the oil pump? Hows it? Is it new? Maybe the oil pressure sensor is faulty confusing the computer into thinking theres no pressure. Generally thr vehcile will not run long or at all with little to no oil pressure. How do you do the motor was it rebuilt or a crate short or long block? It may be faulty and have a bearing kinked or put in wrong blocking a gallery.

 

The engine came from Toyota Car Parts in Colorado. It is a rebuilt long block. A friend performed the install.
Where is/are the oil pressure regulators located? There are no noticeable leaks. The engine came with a new oil pump as an accessory which my friend installed. I replaced the oil pressure sending unit with no change in the very low readings on the OEM dash gage. Therefore a calibrated mechanical gage was attached right to the engine and that is how we found out the exact pressures. The engine runs smooth and does not smoke. I have driven it about a total of 30 miles with no noticeable performance issues and no knocking. As written already, there is plenty of oil under the valve cover as witnessed looking thru the oil fill cap area. The pressure is normal when the engine is cold. I have no way to know if the bearings are installed properly.
Thanks for any advice or tips to troubleshooting this issue.

 

I'm currently looking in alot of other books i have for the pressure regulator and if i am looking correctly it is a very small one on the bottom of the oil pump. consists of a psiton spring retainer and stap ring and i believe a new pump was installed it was left out. You sould as your friend or remove the pump and see if theres a hole in the bottom and its empty then you know the deal. Theres a snap ring that holds it in i bet its missing check it out man i'm still lookin but that prolly it.

 

OK - now I know what you mean by an oil pressure regulator. I think it is also called a pressure relief valve and is designed to open against the retention spring pressure if the oil pump were to for some reason provide more pressure than intended. It is possible the relief valve was not installed or is stuck open.
I still do not understand why the pressure reads correct upon cold start. It begins to drop real low as the engine warms. Maybe the heat is opening the relief valve. This does not seem to explain why the engine still runs smoothly and significant oil is visible inside of the oil fill cap port. ???? I am very confused and continuing to hope for some logical explanations which can be verified or nullified without removing the oil pump or the heads.
Thanks for any and all advice.

 

if you can, contact where you got it from and let them know whats happening. Its possible they did a sloppy job measuring clearances and as the oil gets hot is gets thinner and too thin to fill the bearing journals.
my 3vz in my 92 was doin the same thing when i got it. Turns out the fan clutch was leaking slowly and when it got warmed up the needle on the gage would sit all the way down to the first bar. And the temperature would sit in the middle of the gage. Make sure you're cooling system is working right. A new fan clutch did if for me, but i was too a day too late, headgaskets started leaking. Now i'm waiting for my 3.4 to come in. Good luck!

 

What weight oil are you using? Mineral or synthetic? I am no oil expert, and certainly no numbers, but I noticed my OE oil pressure gauge reads lower with synthetics.

 

The reason the original engine was replaced is because is locked down without warning while driving down the interstate.
I already contacted the place who "remanufactured" the engine. They gave me two options. They send me free of charge a new oil pump to install OR keep on driving and it the engines finally fails, send it back for a free replacement. Due to the many hours of labor required to either replace the pump or remove the engine, tear it down to the long block, send it back, get the next, reassemble and reinstall ....... I am trying to see if there are any suggestions to identify the issue.
The oil is mineral based 10W-40.
What is a good method to determine if the cooling system mentioned by vital22re is working properly?
Is it possible the original problem which caused the original engine to lock up at 148k miles still exists and is causing the current issue with the remanufactured engine?
Thanks for all ideas and input .....

 

I would suggest new oil pump and make sure that pressure ragulator or value is in right and working properly.

 

Remanufacture shop is going to send another long block and oil pump. We will inspect the pressure relief valve before installing the oil pump. They will pay the shipping both directions. Until then the reman shop suggested change the oil to 20W50 Castrol GTX and my installer suggested to replace the Purolator oil filter with an AC Delco since he feels they have less restriction. We will continue to drive cautiously and stop driving at the first knock.
Opinions???

 

20-50 is way to thick. It sounds like a clearance issue. If they just put it together and didnt plastiguage anything the clearances on your bearings are prolly to much. It doesnt take much to lower oil pressure if the clearances are to much. Thats why they want you to run the 20-50 to fill the void they left.Here is a small chart of how oil is thick when cold and what it is hot
Oil type... Thickness at 75 F...Thickness at 212 F

Straight 30...... 250......................10
10W-30............100......................10
0W-30..............40 ......................10

Straight 10........30....................... 6

 

Doesn't sound like a great situation, but at least the people who rebuilt your engine appear to want to take care of you.