370 ex- engine sensors keeping going off

joannwinters

we just purchased a new (40) 370ex. We are in fresh water but dealer had in salt for a few months and the first 40 hours. Amazing boat but the water pressure sensors keep alarming on computer when we go above 3k rpm then it forces us to go below that. We replaced them and still doing that or saying engine is over heating. Thought it might be impellers but those look great. Everything is on the computer so we are not sure if it’s computer or engines. We are on a lake with no service so have to wait on mechanic.  Anyone have any ideas. The guys on our dock are very engine smart but this new beast has them stumped. Engines are 8.2 l b3 DTS with joystick .

Michael T

@joannwinters - I had the same bloody problem with my 2014 EC 360 with 502s and Axius.  It nearly drove me nuts until we solved it.  Water pumps were replaced etc. There were two problems. One was "ghost codes" it took a while for a Mercruiser 5 star master tech to figure it out but the computers were retaining "ghost code faults" even when the problem was solved and the error code supposedly erased using a Mercruiser provided lap top with proprietory Mercruiser programming. These "ghost codes" would trigger false shut downs and prompt rev limits which were a serious problem if trying to dock in a wind and find your rpm was reduced (falsely) to 500 rpm.  I was fuming mad and tore a strip off Mercruiser. The Provincial (State) Mercruiser factory representative had to have a new master program installed (from Mercury) on his personal lap top to fix this. Second, I was told that they were having sensor failures - particularly of the water pressure and water temperature sensors of up to 90%. I called the distributor and he said that was true. I was told it was still cheaper to have them made off shore in some crappy little factory somewhere. I asked what about the labor cost and customer inconvenience not to mention the safety factor......a big reason for bringing manufacturing back to the U.S.A. 

aero3113

You say the impellers look great, take a close look at the housing and see if there is any scoring. If there is, the impellers won’t be able to provide enough water pressure.

joannwinters

Would salt water cause the scoring 

aero3113

It would be more from sand/silt.

earl1z19

What do your temp gauges tell you? Is it actually overheating? Is it one or both motors? I thought all of the 8.2's were closed loop cooling?

Ian

Scoring after 40 hours? Running through gravel?

reneechris14

Clean pick ups?
Clean strainers?
Clean heat exchangers?
My be dealer just had it sitting still for while and biult up some growth?

Glassguy54

like barnacles or mussels in the cooling water plumbing?

LaRea

The water pressure is low, or high? 

High pressure means a blockage downstream from the pump - most likely in the heat exchanger, which is easily checked and flushed.  Low pressure means a faulty pump/impeller or a blockage before the pump. Any of those conditions can happen at any time regardless of engine hours.

Scoring of the pump housing could happen in a few minutes if you run the engines while grounded in sand or coarse mud.  

GMSLITHO

Yep make it here 

joannwinters

Thank you all for the info. Micheal T- we replaced water pressure sensors twice now and they are not working fine. Both impellers are great as well as housing . The port side engine is still throwing alarm . Both engine read 170 while just running 1500rpm. Computer says port side overheating and shuts us down . Everyone is stumped but after reading your post I am thinking it may be computer . We are seeing a merc mechanic today . We were able to run 45mph for awhile a few days ago before the alarm sounded . Now it’s going off while idling. Glad it’s under warranty but need to find someone who knows how to fix it . We live in area that doesn’t have a lot of bigger newer boats 

Michael T

@joannwinters - unfortunately this sounds all too familiar - good luck! MT

joannwinters

Update - water pressure sensors replaced, impellers look great, water pump fine, software updated.  We can take off and run 45 mph and she runs perfect until we throttle down then water pressure alarm goes off.  The SAME thing happens if we are going 10 mph or less - then trottle down and the same alarm.  We cleaned all the intake hoses - did find some debris from being in ocean and hoped it would work but not!  Replacing poppet value and gasket this week as the next step.  We are pretty much positive its a water flow issue - anyone have suggestions? 

Dream_Inn

Thank you for the update.  To me, it still sounds like it could be something with the water pump.  They can look ok, but not be ok.

joannwinters

Thanks we will give that a try.