Merc 5.7 M54 I/B Overheating!

[ThaBoss]

I was out yesterday when I noticed that an engine had gone over 200 degrees. I shut it down and looked at the fresh water system. It was very dirty. I drained and put new water in but still overheated. How do I check the Saltwater cooling system. Does it also have a pump. Any help would be appreciated.

 

[prockvoan]

Re: Merc 5.7 M54 I/B Overheating!

Is this a inboard or in/ob engine?You will have a raw water pump that feeds thru the fwc system,oil cooler too!You need to check if the impellor is bad on the raw water pump or if the pick up/sea strainner is clean for inboards.For ib/ob drives,there is a water pump in the lower unit.

 

[Limeyguy]

Re: Merc 5.7 M54 I/B Overheating!

this might help, just had the same on my 5.7 (although raw water cooled only) turned out to be the thermostat...<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=24;t=013975

 

[rodbolt]

Re: Merc 5.7 M54 I/B Overheating!

the pump for the seawater will be belt driven off the motor or in the drive unit, depends on the model. I have also seen them both together just not from the factory.Bravo units all have engine mounted seawater pumnps. so a tad more info, to include when was the last scheduled maint on the pump, is nessasary.

 

[ThaBoss]

Re: Merc 5.7 M54 I/B Overheating!

I want to thank you all for your help. This is an twin inboard not I/O. It sounds like I need to get the boat out of the water to look at the sea strainner. Beside the engines there is a unit that looks like it feeds the sea water to the manifolds, is this correct? Thanks again!