ISM 500 Low Oil Pressure Warning in Rain

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ISM 500 Low Oil Pressure Warning in Rain

March 22, 2021, 05:05:42 pm

Two times today I got a low oil pressure warning both times it happed in very heavy rain. It rained the majority of my 5 hours driving but when it rained very heavy I got the warnings. Any thoughts on what this could be?? Thanks

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #1 – March 22, 2021, 05:10:21 pm

Certainly water getting into a connector can do that.

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #2 – March 23, 2021, 02:22:21 am

Water can do strange things to electronics. Dielectric grease is your friend.

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #3 – March 23, 2021, 02:21:08 pm

Quote from: wolfe10 – March 22, 2021, 05:10:21 pm

Certainly water getting into a connector can do that.

Any idea which side of the engine the sensor is on?

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #4 – March 23, 2021, 07:30:16 pm

Quote from: jimgior13 – March 23, 2021, 02:21:08 pm

Any idea which side of the engine the sensor is on?

The one you should be looking for is hid below the cam/engine position sensor. Now both are hid behind where the air compressor is attached to the engine. The area is behind the A/C compressor. On some older coaches there is a sensor before the oil filter on the filter base.

Mike

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #5 – March 23, 2021, 09:33:30 pm

Quote from: Pamela & Mike – March 23, 2021, 07:30:16 pm

The one you should be looking for is hid below the cam/engine position sensor. Now both are hid behind where the air compressor is attached to the engine. The area is behind the A/C compressor. On some older coaches there is a sensor before the oil filter on the filter base.

Mike

Hides is a understatement. I did make tools to remove if you need
Scott

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #6 – March 23, 2021, 09:41:24 pm

That little homemade tool is a must to reach that sensor.

Mike

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #7 – March 23, 2021, 09:43:18 pm

Quote from: dsd – March 23, 2021, 09:33:30 pm

Hides is a understatement. I did make tools to remove if you need
Scott

Scott was that a box wrench or socket and what size is it?

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #8 – March 23, 2021, 09:51:39 pm

Not Scott but I made mine out of a socket as it was thinner than an end wrench. I will have to go up to the shop tomorrow to check the size. Scott might remember off the top of his head as he has a younger mind.

Mike

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #9 – March 24, 2021, 12:31:32 am

I will make one just to carry and then I will never need it. Murphy's Law.

Chuck

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #10 – March 24, 2021, 12:31:36 am

Quote from: Pamela & Mike – March 23, 2021, 09:51:39 pm

Not Scott but I made mine out of a socket as it was thinner than an end wrench. I will have to go up to the shop tomorrow to check the size. Scott might remember off the top of his head as he has a younger mind.

Mike

Think I fell on my head too many times. Yes it's a socket cut down and I'll have to look in the morning. Horrible job!
Scott

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #11 – March 24, 2021, 12:37:04 am

Releasing the clip may only be possible after you rotate the sensor. It seemed more accessible reaching up from underneath. Then the sensor I put in was bad from stock. Put original back in. My gauge also has issues, won't go to zero, so I'm going to replace it had keep my fingers crossed. Lol
Scott

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #12 – March 24, 2021, 10:43:09 am

Chuck I will do the same thing.

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #13 – March 24, 2021, 12:02:15 pm

I've got this problem too - also a 500 hp Cummins engine. Mine would occasionally get a low oil pressure signal in good weather. Its got to be a sensor or connection problem. I've got Cummins looking at it & will update on what they find. I know Cummins is the expensive route but my knowledge of engines pretty much ended in '73.

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #14 – March 24, 2021, 03:32:10 pm

I apologize if this is a repeat post as I thought I submitted one earlier.
In any case we also have a 2009 Nimbus with ISM 500 and same thing happened a couple of times.
Check engine light came on during heavy rain in Iowa a few years ago and fault code read low oil pressure.
Took into Cummins in Des Moine Iowa and they replaced oil pressure sensor.
Found out a couple of years later that was not really the problem.
Next time happened during heavy rain en route to Nac for service. Same circumstances and was about 20 miles from Nac and ended up being towed in.
Anyway final problem was that rain was being sucked in thru air intake at back of coach and soaking the air filter. Being soaked and not able to bring in fresh air engine read as fault and shut down.
FOT had a recall a few years ago where they were aware of rain problem and installed a baffle around air intake pipe where water would be diverted around and out and not sucked into filter.
Baffle was installed and no problems since. Just info--the recall was not sent out--only applied if coach brought in for service.
C. Knight
Lindale,Tx

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #15 – March 24, 2021, 03:52:19 pm

Quote from: C.KNIGHT – March 24, 2021, 03:32:10 pm

I apologize if this is a repeat post as I thought I submitted one earlier.
In any case we also have a 2009 Nimbus with ISM 500 and same thing happened a couple of times.
Check engine light came on during heavy rain in Iowa a few years ago and fault code read low oil pressure.
Took into Cummins in Des Moine Iowa and they replaced oil pressure sensor.
Found out a couple of years later that was not really the problem.
Next time happened during heavy rain en route to Nac for service. Same circumstances and was about 20 miles from Nac and ended up being towed in.
Anyway final problem was that rain was being sucked in thru air intake at back of coach and soaking the air filter. Being soaked and not able to bring in fresh air engine read as fault and shut down.
FOT had a recall a few years ago where they were aware of rain problem and installed a baffle around air intake pipe where water would be diverted around and out and not sucked into filter.
Baffle was installed and no problems since. Just info--the recall was not sent out--only applied if coach brought in for service.
C. Knight
Lindale,Tx

Wonder why a wet/restrictive air filter showed as low oil pressure??

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #16 – March 24, 2021, 05:30:34 pm

Don't know why but FOT just said that a fault had to be read and the oil pressure sending units were good after the fix. Go figure.

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #17 – March 24, 2021, 08:52:45 pm

Chuck,

I haven't forgot about the size of the socket that I used. I spent the day picking up a new tractor half way across the state and just got it to the barn. I just got enough energy to go and look at the socket and it is/was an 1 & 1/4"

Mike

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #18 – March 24, 2021, 09:19:35 pm

Dido just got inside. Long day 1 1/4"

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #19 – March 25, 2021, 10:40:56 am

Quote from: C.KNIGHT – March 24, 2021, 03:32:10 pm

I apologize if this is a repeat post as I thought I submitted one earlier.
In any case we also have a 2009 Nimbus with ISM 500 and same thing happened a couple of times.
Check engine light came on during heavy rain in Iowa a few years ago and fault code read low oil pressure.
Took into Cummins in Des Moine Iowa and they replaced oil pressure sensor.
Found out a couple of years later that was not really the problem.
Next time happened during heavy rain en route to Nac for service. Same circumstances and was about 20 miles from Nac and ended up being towed in.
Anyway final problem was that rain was being sucked in thru air intake at back of coach and soaking the air filter. Being soaked and not able to bring in fresh air engine read as fault and shut down.
FOT had a recall a few years ago where they were aware of rain problem and installed a baffle around air intake pipe where water would be diverted around and out and not sucked into filter.
Baffle was installed and no problems since. Just info--the recall was not sent out--only applied if coach brought in for service.
C. Knight
Lindale,Tx

Thank you so much for this. Ironic that a coach named Nimbus cannot be driven when there is CumuloNimbus

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #20 – March 25, 2021, 11:56:47 am

Hav'nt seen one post where anyone actually checked oil pressure and/or oil,what if the sensor was good and you actually had
low pressure,what would you do.You have a sensor telling you low pressure and everyone thinks the sensor is bad,check the obvious first to eliminate one problem.

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #21 – March 25, 2021, 01:51:04 pm

In my case I had checked oil level--all OK and dash oil pressure gauge was where it was supposed to be so who knows how this stuff works!
C.Knight

Re: ISM 500 Low Oil Pressure Warning in Rain

Reply #22 – April 08, 2021, 10:09:59 am

Quote from: Dave C – March 24, 2021, 12:02:15 pm

...... I've got Cummins looking at it & will update on what they find.

Well Cummins finally finished looking at it. My situation was different because the oil pressure drop would also occur in good weather, but very randomly. The tech found that the pressure sensor was reading correctly. They did notice that when you rev'd the engine, the pressure would spike, then bounce a bit before stabilizing. They dropped the pan and found a bit of crud around an oil pressure relief valve. Not much ... but they cleaned it up. I had them replace the pressure sensor while they had the pan off. Total cost was about a coach-buck. Since it was a very random problem, I won't know whether it worked until the summer trip through the Rockies.

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