Low Oil Pressure

[Carl Riederer]

2019 X15 This truck had oil pressure issues in the past. Had to change the oil filter at about 10,000 miles to make it to the oil change. Put a new oil pump in it and that didn't fix it. Did an overhaul and the oil pressure came up and could go a full service without having to replace the oil filter mid-way. Just over a year later it spun a rod bearing. Pulled the engine out and did a full rebuild. Sent the block to a machine shop to be cleaned and checked. We also blew all the ports out. Installed a new crankshaft from {after-market}. One new rod, new head, both gears and hubs in the front, oil pump, oil cooler, oil thermostat, and overhaul kit. When the truck is up to full operating temp the oil pressure will drop to 12psi at idle. Checked with a manual gauge and it is reading correctly. Installed a new set of bearings from Cummins, another oil pump from Cummins and tried one from {after-market}. Installed new piston nozzles from Cummins. Ran it with the valve cover off nothing leaking on the top end. Replaced the oil filter again and the relief valve in the filter head. The oil filter is a filter that we use on other X15s with no issues, so not the brand of filter. Double checked the engine serial #, overhaul kit #, oil pump #, bearing #s, and the piston cooler #s. Checked the oil pickup tube. Can not find the issue.

[marek4792]

Chances are the aftermarket crank could very well be undersized and causing you more grief and now $$ than an OEM crank would've.. OH and if that oil filter isn't a Fleetguard and contains an o-ring where it threads on. There could be very well be a piece of it somewhere blocking an oil passage causing a drop in pressure and trashing a bearing..

[Carl Riederer]

(10-29-2026 )marek4792 Wrote:  Chances are the aftermarket crank could very well be undersized and causing you more grief and now $$ than an OEM crank would've.. OH and if that oil filter isn't a Fleetguard and contains an o-ring where it threads on. There could be very well be a piece of it somewhere blocking an oil passage causing a drop in pressure and trashing a bearing..

We have tried Fleetguards with no change in the past. Even tried their extended service filter with the same issues. This truck had issues with the factory crank. There is an issue somewhere.

[tree98]

(10-29-2026 )Carl Riederer Wrote:  This truck had issues with the factory crank. There is an issue somewhere.

There are different sizes of cummins crank bearings, maybe you have a journal or 2 that are oversized and somehow it got overlooked at the factory and the wrong bearings were installed?? The only way to know is to take it apart and measure everything.

If it has an aftermarket head too it could be hemorrhaging oil badly from one or all the cam bearings. Part of the problem with using all this aftermarket stuff is that now you don't know where to start, none of those parts can be trusted.

[Carl Riederer]

(10-30-2026 )tree98 Wrote:  

(10-29-2026 )Carl Riederer Wrote:  This truck had issues with the factory crank. There is an issue somewhere.

There are different sizes of cummins crank bearings, maybe you have a journal or 2 that are oversized and somehow it got overlooked at the factory and the wrong bearings were installed?? The only way to know is to take it apart and measure everything.

If it has an aftermarket head too it could be hemorrhaging oil badly from one or all the cam bearings. Part of the problem with using all this aftermarket stuff is that now you don't know where to start, none of those parts can be trusted.

We ran it with the valve cover off and didn't notice any major oil flow. This engine had oil pressure issues when the engine had all factory parts. We stopped using Cummins heads years ago do too the valves would pound into the seats in a year and would have too replace them with 150,000 miles. The stage 3 heads fixed our issues with that. We have had problems with factory oil pumps, out of the box also. We looked up the bearing on Cummins Quickserv and put new Cummins bottom end bearings in again. Plastic gauged them this morning to make sure and they are plenty tight. Not sure if the air compressor or if the high-pressure pump could cause the issue.

[tree98]

These engines demandated? That would explain your valve seat problems with heads.

[Carl Riederer]

(10-30-2026 )tree98 Wrote:  These engines demandated? That would explain your valve seat problems with heads.

Yes they are. Hard to avoid that in our area, most of the guys are.

[mikkhh]

Engine running with way too much internal friction from operating in wrong engine modes or having too much timing would explain the oil overheating and therefore causing low oil pressure.

The turbo is still original? Or has been converted to non vgt?

[Carl Riederer]

(10-30-2026 )mikkhh Wrote:  Engine running with way too much internal friction from operating in wrong engine modes or having too much timing would explain the oil overheating and therefore causing low oil pressure.

The turbo is still original? Or has been converted to non vgt?

The turbo is original. The oil temp is normal running 20deg over coolant temp. around 220 oil temp. The truck isn't turned up at all.