Just got truck back from rebuild. Was test drove and was good to go. I bobtailed home...everything was good. Oil pressure up around 40-45 at highway speed @ 1500rpm.
Hooked to a tanker today and drove about 15 miles and suddenly my oil pressure was at 30psi. Pulled into loading facility and stopped at office. Started driving and my oil is at 40psi again.
Got loaded and drove about 10 miles and it's down at 28psi again (60mph @ 1500).
Pulled into fuel station (15psi at dead idle) and popped hood and everything was dry. I checked the oil and it was good. Started up the truck again and now it's at 25psi at dead idle and back to 40-45 at highway speed.
It continued to do this for the next hour until I got unloaded and got home.
Then I bobtailed back to the mechanics shop (about 25 miles)...and oil pressure was perfect the whole time.
I was thinking oil pressure sensor but why doesn't it do it when I was bobtailing? Oil pump (shimmed up) and oil cooler both new with rebuild.
ISX15 2350 oil pressure acting strange
Discussion in 'Trucks [ Eighteen Wheelers ]' started by skman, Dec 1, 2023.
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It's clearly something while under a load. Gauges do goofy things, but being a new rebuild, I'd suspect something in the filters.
skman Thanks this. -
Sensor failure is not uncommon. Inspect for oil wicking into the electrical connector thru the sensor.
Then a mechanical gauge should be installed and check pressures before and after filter. Sounds very erratic.
New cam bearings and rods/mains?High Stepper, lester, QUALITYTRUCK and 1 other person Thank this. -
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I would try changing the oil filter first, easy and cheap to do, after a fresh rebuild we use to change them out after a few hours at one shop I was at.
I don't care for the Fleet Guard filter as they don't have much capacity in the primary filtration side, more by-pass filtering When at the dealership we seen some issues over this. we use Lurberfinder . LFP9000 now. If this is a Peterbilt check the ground wire connections at the left front cab mount area, we have seen erratic gauge issues in the past from poor grounds.Dave_in_AZ and skman Thank this. -
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If it got a new pump on it the pressures can be different from what they used to be. The new pumps also dont use shims anymore either.
I still suspect sensor issues but thought it was worth mentioning.Attached Files:
High Stepper, skman and Dave_in_AZ Thank this. -
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So I got the truck back yesterday. Of course it runs fine in the shop so putting it on the computer didn't really show anything.
They did change oil pressure sensor. Also (when I did the rebuild) I sent injectors in for testing. 2 passed and were re-used. But one of those 2 are returning back too much and causing an spn 157.
Today I took the truck out hoping the leaky oil sensor had been the problem. It wasn't.
I did find out the following yesterday:
It runs at about 40 or so until oil temp hits approx 212-213. As soon as it hits that temp....you can watch the pressure drop off to 28psi.
It doesn't change as you drive...even if oil temp drops to 200F...it will stay about 28-30.
BUT...if it drops under 210F and I make a stop at stop sign and then take off again....the oil pressure comes back up to 40+.
As soon as it hits over 212F...it drops off again. It does NOT throw any codes when the oil PSI issue happens.
Also, now I'm getting code 95 instead of 157 while accelerating loaded. Injector hasnt been replaced yet...so that's probably where that code is coming from.
I'm going to try changing oil filter... just in case. It's a fleetguard on there right now.Last edited: Dec 9, 2023
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Diesel Dave and skman Thank this.
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olddog_newtricks Thanks this.
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