Oil pressure help

[Rich.mork]

So im having issues with oil pressure on my 06 5.9 ... i currently have a mechanic gauge hooked up to the top of the oil filter housing... i get roughly 10psi at 1000 rpms ... the issue is my oil pressure gauge on the dash reads 50ish psi but the sensor isnt even plugged in ... as soon as i plug it in the gauge drops to zero ... while the truck is running and the sensor un plugged why would it read 50ish psi ... (its the one wire idiot light style sensor)

 

[AH64ID]

The OEM setup is based on a pressure switch and the actual pressure reading is algorithm based. Likely a normally closed switch, so when it’s not plugged in the ECM thinks all is well.

It sounds like a bad switch, but you should also have more than 10 psi at 1,000 rpms. You said roughly, is it below 6 psi? The OE switch is a 6 psi switch.

 

[Rich.mork]

Ok .. yea i have a new sending unit just haven't installed it yet need to get the right size socket ...Its 6-7 psi at idle... i said roughly 10 because when i have my buddy hold it at 1000 rpm he could be a little above or below... also the oil pump is brand new ... prelubed and prime it to the vest of my knowledge

 

[Rich.mork]

I also had plugged in the new switch into the wiring harness but did NOT install it into the block oil pressure still read 50 on the dash ..my thought would be that it read zero due to not enough psi (6 psi)

 

[AH64ID]

How long did you run it? The ECM also has a time delay.

6-7 psi at idle is low. Lowest I ever saw was 15 with HOT oil. Normal was 18+.

 

[Rich.mork]

While trouble shooting ..no longer then 1 to 2 minute intervals ... the low psi scares me ... any ideas why the low pressure? .. the mechanical gauge worries me as well... its brand new but its a harbor freight special

 

[AH64ID]

It could be the pressure relief valve in the oil cooler housing, or it could be a faulty gauge.

 

[Prairie Dog]

Keep in mind that the factory "gauge" is a show the puter puts on for us. The sending unit is a simple switch that's on or off. It doesn't reflect any real world pressure other than if you have it or not.

 

[BigPapa]

You said it is a new oil pump. What else has been done?

 

[Rich.mork]

Motor is a fresh build .. pan to carb (minus the carb) lol... this is the first time its been running

 

[BigPapa]

I agree with John if you had the Oil Cooler out. Pretty easy to put the Pressure Relief Valve together improperly or leave something out. I'd double check, too, that you got the correct gaskets. Seems I remember there are a few different ones that have different port holes.

 

[Rich.mork]

I have a new pressure relief valve on hand... i plan to take a look here in the next day or so .. ill keep you guys posted... and the gaskets came from Cummins off the S/n on the block so id assume their correct but ill double check..thanks!

 

[BigPapa]

Here's a diagram and Parts List of your Oil Cooler.

 

[Rich.mork]

Updated..pulled the oil cooler housing ..verified gaskets are correct changed pressure relieg, installed new oil pressure switch .. fired it up ..still 6 psi at idle..10 psi at 1k rpms ... i could drop the oil pan and make sure the pickup tube is tight but im 99% sure it is fine .. also has new gasket as well ... any other ideas?

 

[Rich.mork]

However im convinced the pressure regulator plunger is stuck ... guess i get it to donit all over again tomorrow..

 

[sojoe]

While trouble shooting ..no longer then 1 to 2 minute intervals ... the low psi scares me ... any ideas why the low pressure? .. the mechanical gauge worries me as well... its brand new but its a harbor freight special

You are putting a lot of faith in a HF gauge?
Hope you get it figured out-best of luck to you

 

[DavidC]

Easy enough to check gauge if you have an air compressor.

 

[sojoe]

But what if it is a HF compressor
JUST KIDDING

 

[brods]

This sounded familiar. Here is a thread with a similar issue: https://www.turbodieselregister.com/threads/new-engine-losing-oil-pressure.266861/

See post 25 where the OP says the regulator plunger was stuck.
Hopefully that thread will help you figure yours out.

 

[Rich.mork]

Front oil galley plug behind the cam gear... fired it up 58 psi... thanks everyone for the help