3.7l 165 hp i/o freshwater cooled overheating. Please help. I want to get out there

[Pbdy Jr]

I have done so much to this boat and now it is overheating on me. I don't know much about this cooling system so I desperately am seeking advice. What would cause it and where do I even begin to troubleshoot? It has a freshwater cooled self contained system. After i ran it for a bit the overflow container was releasing steam. I shut off the boat. The. water/antifreeze was boiling in the overflow container.

 

[Don S]

Re: 3.7l 165 hp i/o freshwater cooled overheating. Please help. I want to get out t

Ever replace the impeller in the sterndrive? You may have a blown head gasket. Common problem with those engines once overheated for any reason.
What's the serial number of your motor? Year would help a little.

 

[stonyloam]

Re: 3.7l 165 hp i/o freshwater cooled overheating. Please help. I want to get out t

Don is right, If you have not replaced the impeller in the outdrive recently that is likely your problem. Now that you have overheated it you need to do a compression check and cooling system pressure test to assess the damage (if any).

 

[Bt Doctur]

Re: 3.7l 165 hp i/o freshwater cooled overheating. Please help. I want to get out t

And you do realize you MUST HAVE WATER TO THE LOWER UNIT TO EVEN RUN THE ENGINE.

 

[artificialreef]

Re: 3.7l 165 hp i/o freshwater cooled overheating. Please help. I want to get out t

You have to always keep an eye on your temp gauge on these motors. I would rather have read 3.7l running hot. How hot did it get? I bought a used basket case and started her up and watched the temp climb to 150, then 160, then 170 and i shut her down. Never overheated her and found a doughnut where the impeller was supposed to be. She runs a cool 145 now. Do you have the 4 inch heat exchanger? Compression test definately needed now.