What oil pressure with Newly Rebuilt 4y engine

Just had my 4y engine rebuilt. Before it went in my oil pressure was in the middle of the normal pressure markers at 3000rpm and about 1/4 up from the bottom when idling. Now with the new rebuilt engine it is at the bottom line at 3000rpm and only 1/8 up from bottom. So it is time to put a gauge on it. Anyone know what these numbers should be with a newly rebuilt engine?

MT

Was the sending unit replaced with the engine rebuild? It's not really an apples to apples comparison if it's a different sending unit. I found aftermarket sending units to be of poor quality of late with their resistance frequently being out of spec from OE. As far as correct pressure, the manual calls for 4.3 psi or more at idle and 36-71 psi at 3000rpm both specs with the engine at normal operating temperature.

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Originally Posted by originalkwyjibo

Was the sending unit replaced with the engine rebuild? It's not really an apples to apples comparison if it's a different sending unit. I found aftermarket sending units to be of poor quality of late with their resistance frequently being out of spec from OE. As far as correct pressure, the manual calls for 4.3 psi or more at idle and 36-71 psi at 3000rpm both specs with the engine at normal operating temperature.

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IN the manual? Crap, did not see it. Thank you

Another thought before I take the measurement and potentially screaming at the Machine Shop.
I know Tim had said in one of the oil pressure threads that the minimum we should see at hot idle was about 12 PSI.

I guess my question is what is the norm folks would see on a newly rebuilt engine. I think his point was 12PSI was a minimum after many miles like 200K.

Assuming the pressure reduces over time I would have to think that the typical pressure on a newly rebuilt would be higher allowing it go another 200K before it bottoms out at 12PSI again.

Just want to make sure this guy did not screw me up with this.

Anyone have any thoughts on this?

Thanks for the response thus far.
MT

I think you should out a gauge on it and find out what reality is.
As long as your within specs with what the factory says all should be good.

Factory sensors are notoriously inaccurate, granted the change from before to now is extreme and I would have expected higher numbers from a tighter motor but until you know what the reality is theres no point getting upset ahead of time.
It might just be time for a new sender

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Originally Posted by Burntboot

I think you should out a gauge on it and find out what reality is.
As long as your within specs with what the factory says all should be good.

Factory sensors are notoriously inaccurate, granted the change from before to now is extreme and I would have expected higher numbers from a tighter motor but until you know what the reality is theres no point getting upset ahead of time.
It might just be time for a new sender

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My thoughts exactly BB. I remember your suggestions when looking for a good shop and I took every precaution.

I will get the real numbers and let you know.

Thanks again

Before I rebuilt my engine it had low oil pressure. This was suspected based on the factory gauge, and verified using an oil pressure tester gauge set.

After the rebuild the factory gauge was about where it was before the rebuild. Worried, I quickly checked it using the gauge set. It tested on the high side of normal per the FSM.

I'm not sure if it is the gauge, or the sending unit. I never did any further diagnosis. What I can say, is that in my case, the factory gauge had the same/similar low readings with lower, and higher pressure. I'm not surprised, factory gauges are designed to make a very broad range, that an engine typically runs at, appear normal on the gauge. When they malfunction they do strange things.

Thanks VanCo:


I am tending to think the same thing. I will know more when I get it measured. Lots of money spent only to get back to low pressure. You are probably right. I will report in when I know.

MT

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Originally Posted by MyToy

IN the manual? Crap, did not see it. Thank you

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The information I quoted was found in the "Lubrication System" section of the FSM.

Hello everyone

Just got the numbers in on the newly rebuilt 4Y from my 86 LE.

They came back with a low pressure number when at operating temp of 22lbs.

The pressure sender was in fact bad. Now it response respectively.
So for any of you that are questioning your pressure and has not tested with gauge you may want to do that and/or replace the sender.

I am happy now:)

Oh very nice detective work, which pressure sender and part number did you end up using?

Thank you:thmbup:

JDM

Maybe this is a silly question, but do you just hook a gauge in place of the sending unit? I have a van which i replaced the head gasket. It didn't run when I got it so I didn't get to see what the readings were before hand. it seems to run alright with the exception of a slight knocking from somewhere in the bottom end. I am hesitant to run it until I m sure the oil pressure is good to go.:redvan::yellowvan::greenvan:

Been off the grid here. So will respond to both questions:

I am not sure about the type of pressure sender but I will try to find out. I looked up at it and it is huge. Nothing as I imagine

I think you just hook up the pressure gauge to the same port as the pressure sensor.

Hope that helps

MT