Coolant Pressure Exp Tank

[BobFino]

Hello, Did a lighted boat parade at idle speed and my Coolant pressure alarm went off and now reads zero. However the monitor is still showing green and the MAN's didn't miss a beat. Shortly after that, the "Coolant pressure at the water pump" sensor alarm sounded, not sure if the two are related. Not sure why the coolant exp tank lost pressure yet and I need to pressurize again. I believe it should be at 11 PSI. One more note, now when I start the engines and bump them up to about 1000 RPM the Coolant pressure sensor now reads normal. Any feedback would be appreciated
Thank you

 

[Skip Boyer]

Im not familiar with the Mann diesels, but it sounds like you have a pre-pressurized cooling system ? If this is the case and the system has lost its pre-charge then i would look for a leak. Pressurize the system, look for signs of a leak. If none are located right away then let it sit and recheck periodically. Im sure someone that has some experiance with the Manns will respond as well. Good luck.....and Merry Christmas

 

[bmac]

Hello, Did a lighted boat parade at idle speed and my Coolant pressure alarm went off and now reads zero. However the monitor is still showing green and the MAN's didn't miss a beat. Shortly after that, the "Coolant pressure at the water pump" sensor alarm sounded, not sure if the two are related. Not sure why the coolant exp tank lost pressure yet and I need to pressurize again. I believe it should be at 11 PSI. One more note, now when I start the engines and bump them up to about 1000 RPM the Coolant pressure sensor now reads normal. Any feedback would be appreciated
Thank you

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Bob

I had a similar issue that was intermittent. It turned out to be a bad sensor that I replaced earlier this year. Mine was an easy fix. Good luck.

 

[BobFino]

Thank you for the input. Right after the Holiday I will take a better look.
Merry Christmas