1995 Sea Ray 220 open bow with Mercruiser 5.7 carb Alpha 1 Gen II / 200 original hours in fresh water boat that is new to me this season.
> Test drive and 1st trip out on lake were pretty short trips and boat operated as should. I did not pay a lot of attention to temp, but I recall it running just shy of dead center just under the 50 degree mark.
> 2nd trip: - Noticed that it would get up to the 165-168 mark but seemed to cool down as I would increase RPM - Did not think much of it.
> 3rd trip: moving at idle speed in cover looking at some houses when boat overheated and alarm sounded. Initially I shut off engine, then I recall that it would cool off when increasing RPM so I started boat and increased RPM and it started to cool back down and w/in a few minutes It settled in at about 168 to 171 degrees. Boat was supposed to have just had the impeller replaced prior to purchasing the boat. All mechanics in my area are 4 to 6 weeks out so I was trying to tackle myself.
> Cleaned out thermostat housing and installed new 142 degree thermostat. Housing was full of crud but I cleaned it all out - No change.
> Went ahead and replaced complete impeller kit - Noted when I removed old impeller it looked bound up and had a couple of the blades pointed in the wrong direction. - Took back out on lake and still running at 168 - 171 degrees
< removed all 4 upper cooling hoses as well as the feed hoses and all are open.
> Have taken boat back to the lake twice and went on two long trips that were about an hour each and ran the boat at about 3200 to 3500 RPM consistently and the boat runs great but still running around 169 degrees It cools down just a couple of degrees at idle speed but pretty much has settled in between 168 and 171
> I noted when I installed the thermostat that Mercury shows you can install either the original 140 degree or a 160 degree. I chose the original 140 degree .
Questions: Where do I start next? Is it ok to run the boat like this until off season?
>Should I go ahead and remove the main water pump from the front of the engine and check that? Could a cracked head cause this condition? Should I try a 160 degree thermostat? What should I try next? Thanks
>
> Test drive and 1st trip out on lake were pretty short trips and boat operated as should. I did not pay a lot of attention to temp, but I recall it running just shy of dead center just under the 50 degree mark.
> 2nd trip: - Noticed that it would get up to the 165-168 mark but seemed to cool down as I would increase RPM - Did not think much of it.
> 3rd trip: moving at idle speed in cover looking at some houses when boat overheated and alarm sounded. Initially I shut off engine, then I recall that it would cool off when increasing RPM so I started boat and increased RPM and it started to cool back down and w/in a few minutes It settled in at about 168 to 171 degrees. Boat was supposed to have just had the impeller replaced prior to purchasing the boat. All mechanics in my area are 4 to 6 weeks out so I was trying to tackle myself.
> Cleaned out thermostat housing and installed new 142 degree thermostat. Housing was full of crud but I cleaned it all out - No change.
> Went ahead and replaced complete impeller kit - Noted when I removed old impeller it looked bound up and had a couple of the blades pointed in the wrong direction. - Took back out on lake and still running at 168 - 171 degrees
< removed all 4 upper cooling hoses as well as the feed hoses and all are open.
> Have taken boat back to the lake twice and went on two long trips that were about an hour each and ran the boat at about 3200 to 3500 RPM consistently and the boat runs great but still running around 169 degrees It cools down just a couple of degrees at idle speed but pretty much has settled in between 168 and 171
> I noted when I installed the thermostat that Mercury shows you can install either the original 140 degree or a 160 degree. I chose the original 140 degree .
Questions: Where do I start next? Is it ok to run the boat like this until off season?
>Should I go ahead and remove the main water pump from the front of the engine and check that? Could a cracked head cause this condition? Should I try a 160 degree thermostat? What should I try next? Thanks
>
