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| I have a 1996 M11 with fluttering oil pressure at high idle. Will run at 34psi then drop 6 to 8 and back up to regular pressure. At low idle the pressure is 20 to 22 psi. No up and down pressure at idle. The question is where to start. Oil pump or pressure regulator valve. I installed a test gauge to confirm and got the same results. Anyone with the same experience? Seems both issues are not uncommon on a M11. The motor has about 600,000 miles and is otherwise sound. Could possibly be a suction tube issue but I would expect the same problem at idle.
Thanks in advance
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algona iowa | Not sure of how the oil pump is put together on the m 11 but I have seen oil pumps on n 14's fail and act like that high rpm's the drive gear for the pump will spin on the shaft at high rpm's oil pressure will drop then you slow engine down or shut off start back up and has oil pressure until you go to high idle again. |
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Leeds, North Dakota | Timothy, when where rods and mains done? overhead set? diluted oil? hopefully tommoww-5088 will chime in, Scott. |
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Agent Orange: Friendly fire that keeps on burning. | I second your opinion. Loose oil pump gear on driven shaft.
You can check by removing tube and jamming a screwdriver between the oil pump gears and then bar the motor over. if the gear isn't tight on the shaft the motor will turn. You almost have to see it to believe it, but it's a fairly common problem |
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| Chased a low oil pressure issue on an m11 last summer. I changed the oil pump thinking that was the issue but didnt change a thing. Started pulling rod caps and the bearings were starting to flake pretty bad. Figured out after i pulled the regulating valve out that the bearing flakes had stuck the plunger in the barrel and it was just dumping oil. Its a lot easier to check out the pressure regulating valve than to change the oil pump. |
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| The truck is new to us and I don't have a complete history on it. I may pull the pan and check the regulating valve, while there I can check the rods and main bearings before I start in on the oil pump. Think I will land up doing the oil pump and reg valve and hopefully solve the problem. When it's warm the oil pressure never drops below 20 psi at low idle. I would expect lower oil pressure if the bearings were worn. The oil pressure is stable at low idle making me think it is something other than bearings.
Thanks for the input. |
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| Had an M11 in a 1997 CaseIH Austoft cane billet harvester set at 330. Fluctuated like you say. Ran me a mechanical gauge into the cab after changing the electronic gauge.
Meanwhile, I had to lift the engine to access a crack in the oil pan. Pulled the caps. All were good. That was at 1400 hrs in 1999ran it to 38xxhrs in 2005, sold,it, he put 7 seasons, probably 2800hrs, and it is now in Honduras, on the original engine.
Don't worry too much. I never liked the engine,,but it did hold up. |
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Cummins M11 oil pressure issue
