Low oil pressure after overhaul?

[siegler]

The mcmaster carr spring got installed yesterday, along with the regulator valve from my broken header and another bundle that I cleaned (just in case the one on the engine was plugged...). Made no difference. 20 psi cold idle, 30 psi cold at 2000 rpm or over. 10 psi hot idle, 20-25 psi hot at 2000 rpm or over.

I DID find the specs for the oem spring in the service manual though. 1.547" free length, 0.915" test length, 5.82+/-0.29lbs test load. That gives a spring rate of 8.75-9.75 lb/in. After measuring the regulating valve where pressure acts on to open the valve and lots of calculating the oem spring allows the valve to open at 50-58 psi, where the mcmaster carr one opens at about 57-58 psi. Valve would be bottomed out (all the way open) at 71-72 psi with the oem spring and 73-74 psi with the mcmaster carr spring. That is really close.

I'm going to say the issue is probably not the spring. What else can it be. Oil isn't foamy after a run, so I think the pick up tube is ok, plugged pick up maybe? Oil jet came out after less than 50 miles of use? oil pump is actually weak? Oil pump didn't get mounted quite perfect and is bleeding by on the mounting face? Reading oil pressure at the turbo isn't the best place and I actually don't have low pressure?

Here is the pressure sensor for my gauge. It's all 1/4" pipe there fed by and 1/8" hose coming from the oil gallery at the bottom rear of the block on the driver's side.

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[riotwarrior]

Try another guage?

 

[Shawn MacAnanny]

Did your machine shop clean your oil ports? I've tried 2 gauges and still have the similar issue. I know everyone says mechanical, but i feel mechanical are far less accurate. I'd be interested to send my spare glow shift gauge and sender to someone who has "good" oil pressure with their mechanical gauge and see what they get with an electric one

 

[riotwarrior]

Did your machine shop clean your oil ports? I've tried 2 gauges and still have the similar issue. I know everyone says mechanical, but i feel mechanical are far less accurate. I'd be interested to send my spare glow shift gauge and sender to someone who has "good" oil pressure with their mechanical gauge and see what they get with an electric one

Just go to air compressor...dial down reg to 45 lbs...check guage...easy peasy

 

[Shawn MacAnanny]

I've found the accuracy isnt off at higher pressure its usually off at the lower though. I had one gauge showing no pressure and the new autometer showing 6psi at the same coolant temp and idling condictions. I found the one sender was only rated from above 10psi, several are like that. I went with a digital autometer so there were no stepper motors, just i direct OHM reading and calculation from the sender, the fewest possibilities for error.

 

[riotwarrior]

I've found the accuracy isnt off at higher pressure its usually off at the lower though. I had one gauge showing no pressure and the new autometer showing 6psi at the same coolant temp and idling condictions. I found the one sender was only rated from above 10psi, several are like that. I went with a digital autometer so there were no stepper motors, just i direct OHM reading and calculation from the sender, the fewest possibilities for error.

Thiz is true for most things like torque wrenches...bathroom scales...and guages...the mid point scale on most pressure and temp type guages are the most accurate area.

I am a very big fan of MECHANICAL guages...NOT electric.

Just as said...plumb up adapter...fit to an air comp...slowly dial up air pressure and test your guage...easy peasy

JM7.3CW

 

[siegler]

Update:
I put my VDO pressure sensor in the factory switch location and the factory switch on top of the turbo where the VDO sensor was. I now get 40psi cold idle, 60psi cold over 2500rpm, 15 psi hot idle, 40psi by 2000rpm hot and 40psi at governor hot.
I guess it was the sensor location all along?

 

[MTKirk]

Update:
I put my VDO pressure sensor in the factory switch location and the factory switch on top of the turbo where the VDO sensor was. I now get 40psi cold idle, 60psi cold over 2500rpm, 15 psi hot idle, 40psi by 2000rpm hot and 40psi at governor hot.
I guess it was the sensor location all along?

Those numbers are within spec. The ford manual shows minimum of 10 psi @ 700 rpm and 40-70 @ 3300rpm. If you want to keep pressure higher when hot maybe try a good synthetic, they won't thin out as much at higher temps. Also, may be you're running a little hot? In any case as long as your flow is high, I don't see anything to worry about.

 

[siegler]

I'm not terribly worried about the pressure now, would be nice to have it 10psi or so higher at cruising speed, but I'm not gonna fuss with it unless that McMaster Carr spring gives out or something. After I have a few thousand miles on the engine I will be switching to amsoil 15w-40. The hot pressure was with the engine at 190*-200*.