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Buddy
Buddy, Technician
Category: Heavy Equipment
Satisfied Customers: 730
Experience:  20 years experience. Freightliner tech for last 14 years
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I have a 1999 Freightliner century class with a 60 series Detroit.

Customer Question

I have a 1999 Freightliner century class with a 60 series Detroit. I'm having low oil pressure is displayed, engine protect light and chk engine light come on and then motor shuts down. Only seems to be doing this going into a climb. Motor fires back up fine after turning off. Oil pressure always been around 40psi since complete overhaul 2.5 yrs ago. It seems to be jumping between psi readings and was wondering if this may all be caused by the oil pressure sensor? Already checked and found the gauge to be electronic, so its not the gauge. Oil levels are above normal with no out of the normal leaks. Oil pump was also replaced at time of rebuild I picked up a oil sensor and going to through that in in the morning. Any other advise to what it might be and if I'm wasting my time changing the sensor? I'm on the side of the road at the moment.
Submitted: 5 years ago.
Category: Heavy Equipment
Expert:  Buddy replied 5 years ago.

HiCustomer Welcome to JA. I am Buddy, and i will try and help you out. The oil pressure sensor could be at fault. I would recomend compare readings to a manual gauge. If pressures are different , then your sensor would be at fault or gauge. Could also compare reading from a reader or laptop and the gauge. They both use the same sensor for oil pressure.The sensor is at rear of block on drivers side of engine. It takes a deep well 1 1/4 socket to take it out. If pressures are the same, i would recomend dropping oil pan and checking regulator and relief valve. These valves are very common to score up and cause pressure problems.If you have anymore questions, just ask.

 

 

Thanks
Buddy

Expert:  Buddy replied 5 years ago.

Also , you said your oil is above normal. I would make sure it does not have fuel in it. If it does have fuel in the oil, this would cause low oil pressure also. If you have anymore questions, just ask.

 

Thanks

Buddy

Customer: replied 5 years ago.
Ok I'm going to go ahead and change the oil sensor in the morning. It started doing this earlier today then after I shut down truck for a hour I then restarted and ran it for 45 mins and everything ran perfect, then suddeningly it started to do what I mentioned above again. Really hoping I can fix this with the oil sensor don't want to have to get towed to the shop.
Expert:  Buddy replied 5 years ago.

What pressure is it running? Does pressure just drop off or does it jump around.

 

 

Thanks

Buddy

Customer: replied 5 years ago.
When cold it idles at 20-22 and when running around 17-1800 rpm it runs about 40-45 when it warms and truck is rolling it jumps around on the lower end about 25-30. But can jump to 40 as well.
Expert:  Buddy replied 5 years ago.

That is a little low there. It is possible the sensor, i have seen several give false readings. It is gonna be tough to get to in the century class, and be careful and hold socket straight on sensor, because if it gets sideways a little bit it will break the top off the sensor. I would also inspect wires at the plug, they are very common to rub and short out about a inch or two back from plug. I hope that fixes your problem.

 

If that dont fix, I would definatly make sure oil is not over full, because fuel will cause low oil pressure. If you have to be towed, i would get a manual gauge hooked and verify it has low oil pressure. Then i would try oil filters and do a plug check and look for metal on oil plug. Then i would check regulator and relief valves in oil pan. I hope this helps you out.Good luck on sensor. If you have anymore questions, just ask.

 

Thanks
Buddy

Customer: replied 5 years ago.
well it's not the oil sensor. I'm trying to make it to a shop. It's only having problems when the trucks climbing. Any other suggestions on what it might be?
Expert:  Buddy replied 5 years ago.

Sorry to hear that didnt get it. Here are a few things it could be.I would first try manual gauge to verify you are getting correct pressure.If pressure shows different it would be in wiring or ecm. If pressures are the same it could be oil filters,diluted oil, regulator and relief valve, piston oilers, rod bearings, main bearings, or cam bearings. I would think bearings would be okay, if engine was overhauled 2 years ago with genuine detroit parts. I would try oil filters and do a plug check on oil and make sure no signs of metal in oil. If that didnt get it, i would then check the regulator and relief valve in oil pan. I see these valves cause problems alot. Especially the relief valve . I hope this helps you out. If you have anymore questions, just ask. Also let me know what you come up with.

 

 

Thanks

Buddy

Customer: replied 5 years ago.
Wonder if theres any chance that the foot thottle sensor could have anything to do with this. The sensor is out.
Expert:  Buddy replied 5 years ago.

Sorry for the long delay in repsonse. I

 

You dont have any throttle response? Did this just happen?

 

The oil pressure sensor is on the engine harness. The tps is on the vehicle harness. It is very rare for this to cause a problem with your oil pressure. But this being said, i have once run into problem with tps wires shorting out and caused all engines sensors to code 5volt supply low.

 

If you have anymore questions, just ask.

 

 

Thanks

Buddy

Buddy, Technician
Category: Heavy Equipment
Satisfied Customers: 730
Experience: 20 years experience. Freightliner tech for last 14 years
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