Alarm Going Off for Mercruiser 350 Mag MPI

Rich990

Cadet
Joined
Aug 16, 2021
Messages
7
Glad your fixed but 5.5 hours to replace is a bit much. Doesn't take me that long and I have to hank upside down to get
I thought the same. In the videos online, it seems like the mechanics are doing this in an hour or two. He said it is in a particularly bad spot in my engine compartment. I know I am supposed to have this done as regular maintenance, but that's a steep price to pay every time you get an impeller replaced. I am getting a little older. Maybe I should retire from watersports and just get a Pontoon. Oh the joys of boat maintenance.
 

Drcoffee

Petty Officer 1st Class
Joined
Aug 26, 2021
Messages
220
Im new here and new to boating. Been 15 yrs since I had my last boat. Im just spit-balling here. If you get an air pocket under the T-stat in will prevent the water from touching the T-stat and stop it from opening, causing an overheat condition. The sensor may still read low but engine running too hot. Does your T-stat have an air bleed hole in it? If not, drill a 1/8” hole in the flange. It wont allow too much water past the T-stat, but it will let air escape. It could be why it only happens at initial start When the cooling system is empty.

a strong impeller could force water past that point, but a weak impeller might have trouble generating enough water volume.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,342
Hmm. My mechanic said his device cost $6000. I did see this online, but it looks like you might need to buy the software for your specific engine. https://autoplicity.com/11229985-si...eDbNRy3IAjqIWaYK1XzIq88_GR_gfPkcaAhQVEALw_wcB
The vessel view mobile will defo work with that engine. Plug and play. It’s by no means got the funtion of a dealers diagnostics…but definitely tells you faults and their description too. As well as dozens of other data read outs that the dash just won’t tell you. I have one for my mpi. Great thing.
 
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