fresh rebuild no oil pressure at idle when hot

dangerous06

dangerous06

diesel tech
Joined
Mar 24, 2008
Messages
3,564
Fresh build start up normal test drive normal stop at light and check gauges light comes on Oil pressure at zero yikes. Shut off check fluids all ok start up head home all ok sit at idle bamm zero oil pressure! Put a real guage on it and when cold 25psi at idle when hot ZERO! TOUCH PEDAL AND INSTANT OIL PRESSURE. let off idle 5 seconds zero oil pressure anybody have an Idea?
Already changed out the pressure spring no change. All I can assume is builder left out a plug somewhere! But where! has pressure just above idle about 800rpm.
 
I have had issues with mechanical gauges on my vw's getting air in the reference line when you get into hard angles at low engine speeds. This then scares the hell out of you on flat ground at idle on the top of the hill when the gauge says ZERO! Is it possible you have air in a reference line?
 
Cold pressure should be at least 50. I've seen wrong bearing sizes used on the crank, galley plugs left out, and oil coolers that have blockage. Usually I just put a big oil pump in to be safe. 50 psi hot idle is common with a big pump.
 
I had an issue with a brand new Cummins marked with China oil pump. It did not set all the way in the block and allowed oil pressure to drop at idle. Pull the front cover and make sure it's seated all the way in the block. If I can find the pics on my phone I will post them
 
First picture is the old pump I swapped back in to see how it sat. 2nd is the new pump and you can see the gap at the bolt hole
 

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yeah I'm gonna have to pull the front cover and check that pump for sure! I hate rework but this one I have to fix for sure ASAP!
Thanks DISTURBED!
 
OK Torn down nothing out of the ordinary so put a new pump in and STILL 40psi cold and zero when hot AT IDLE. Right off idle 40psi and steady. WTF??
 
It has a leak somewhere that it’s overcoming.
For instance, when the check ball comes out of a hpop on a 6.0, no oil pressure on the gauge at idle... the slightest bit off idle and boom!!! Oil pressure.


Sent from my iPhone using Tapatalk Pro
 
Well besides a complete tear down guess I'm stuck with it! Fill it with Lucas!! LOL
 
Did you check main/rod bearing to crank clearance when assembled? Check oil pressure at turbo pressure port on oil cooler/filter housing. Maybe wrong cooler gaskets? I'm going from memory, since service manual is at the shop. Oil then goes to oil galley in the block on injection pump side. There is a soft plug behind the tappet cover in the crossover galley. There should be plugs at front and rear of the main oil galley. Did you put oil squirters in the block, below the main bearings?
 
My builder has been putting motors together for me for years. I'm sure something was missed! really sucks I have to pull the motor! So my builder is giving me another motor but I'm screwed for time and my customer is screwed for inconvenience! At least he understands! I put straight 40 weight in it for the time being till we can set up a time to get this done!
Changing the regulator did nothing as I assumed. But was a wish!!
 
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