Yep, 2.9 oil pressure low

[Crash_X]

Hi all.
I know this is old problem, but I'm not finding a answer.
1990 2.9, 4x4.
Truck was fine last night, today no pressure.
I know about the gauge and sending unit crap( thanks ford).
Put manual gauge on, 15 lbs cold, no increase with rpm.
Screen shouldn't be plugged (yeah right) as I put this engine in last year, ( used w/85k, checked and measured bearings, they were good).
Hate to try and pull the pan, but I dont know what's next.
Thanks all

 

[RonD]

Change the oil filter first

15psi is fine, anything above 6psi with hot oil is fine as well

Remember oil pressure is the oil the engine CAN NOT USE at that time, so it backs up in the main passage and oil pressure goes up
It is odd it doesn't go up with RPM, but its NOT GOING DOWN either which is VERY VERY GOOD, lol
So if there is no "extra noise" at idle or high RPMs then you are OK for now

The valve train will get very noisy, even noisier on 2.9l, when pressure is below about 4psi

Bad or clogged filter could cause what you see
Failed oil pressure by-pass valve in the oil pump as well, which would mean dropping the oil pan

Extreme Long shot is an "open bearing", its passing oil thru faster than it should, so pressure can't go higher

 

[Crash_X]

How about this as a thought,
Could the pumps pressure relief spring have broken

 

[Crash_X]

Change the oil filter first

15psi is fine, anything above 6psi with hot oil is fine as well

Remember oil pressure is the oil the engine CAN NOT USE at that time, so it backs up in the main passage and oil pressure goes up
It is odd it doesn't go up with RPM, but its NOT GOING DOWN either which is VERY VERY GOOD, lol
So if there is no "extra noise" at idle or high RPMs then you are OK for now

The valve train will get very noisy, even noisier on 2.9l, when pressure is below about 4psi

Bad or clogged filter could cause what you see
Failed oil pressure by-pass valve in the oil pump as well, which would mean dropping the oil pan

Extreme Long shot is an "open bearing", its passing oil thru faster than it should, so pressure can't go higher

Thank you
Lifters are getting loader each time I run it.
The 15 psi is on a crapy gauge and could be closer to 10. And that's a cold run.
Knowing of the gauge bs, when I put this engine in. I put a manual gauge on it to see what it had.
Was great at idle and raised with rpm.
I drive it every day, and like I said, good last night, dead today.
Happy you mentioned the bypass.
I didn't see your response as I was typing.
Thanks for your help

 

[Crash_X]

Is the pressure read before or after the filter?
On my way to get a filter and a good gauge

 

[RonD]

After filter

Oil Pump >>>(by-pass)>>>>>filter>>>>>main oil passage>>>Pressure switch/sender>>>engine oil passages

If valvetrain is making more noise then oil pressure is for sure low

 

[PetroleumJunkie412]

What do you have on it for a filter?

Had a Mobil 1 filter royally fail years ago, same symptoms.

 

[Crash_X]

Ok all,
Lucky as can be.
Plugged filter!!!!
Only had 5k on the oil (shame on me), didn't think it would plug up. I have run much longer on a oil change.
I now have 50 psi cold on a real gauge.
So all is well and I dont have to drop the pan.
Thank you RonD for responding and telling me what i should have already known.
See you all next time with the next great adventure with my wonderful piece of ford.
YES I LEARNED,,, CHANGE YOUR DAMED OIL!!!!!

 

[RonD]

Good work

Thanks for posting the fix

 

[Crash_X]

Good work

Thanks for posting the fix

Thanks for the help