over heating

[andrewfrotier]

Hello All
So here is my issue! I have a 1987 Sundncer with win 454s. I purchased the boat in 2012 and had the boat checked out top to bottom all checked out very well. The port engine was replace in 2002. This engine now has developed an over heating issue. From a cold start the engine comes up to temp about 145 stays their for a min then starts to clime up to 200+ the funny thing is once I get up and moving about 6-7 knots it comes right back down to 145-155' but as soon as I go back to Idle or below say 6 knots or 800rpm or less its climes right back up. The sea strainers are clear! Has anyone had tis issue? I had the Impellers redone when I bought it in 2012( but the guy that did the work I did not know, as the seller had it done and he seemed shifty to me? Like he might have done some of the work and not all of it? I did not see him do the work but then again I could just be paranoid) So does anyone have a suggestion? Pump? Impeller? Thermostat?
Thanks
Andy

 

[hottoddie]

First confirm that the motor is overheating using an infrared thermometer on the thermostat housing. Then check the water flow coming out the 2 exhaust ports to see if are similar. My bet is the impeller on the port engine is toast. Also check the riser temps while your at it.

 

[1990-270-da-lover]

+1 on the impellor, 2012 is enough time lapse with or without use for the impellor to degrade. I'd replace both so you know when they were knew and can plan a service interval for them. Good Luck.

 

[Chief Alen]

Start with the impeller, then change out the t-stat, and if that doesn't fix it pull the elbows / risers.

If they are clogged time for new ones.