High temp (no thermostat)

[OHfishing]

Owned a 1987 searay sundancer 250 for about 3 years. Previous owner had thermostat removed and it always runs in the 120* range on the dash. Fished with the boat in cool lake erie all spring never had a problem ran like a dream.

2 months ago broke my hand and the boat sat at the dock for 2 full months without being started. This weekend came up to the lake to prepare for the marina to pull it out and winterize it.


Started up fine idled fine a mile or so out of the harbor and I open up the engine once reaching the main lake.

After a minute or 2 wide open i noticed the temp needle pegged at 220 (max) and I have never seen that before so I throttled down to just above idle and the temp quickly went down to normal range.

I thought maybe I had zebra mussels or something covering the intake and decided to try again today.

Same thing. Started fine temp stayed fine until I reached main lake and temp did same thing when I Layed onto the throttle went quickly to 220...i layed off to mid throttle and temp went back down.

Thw boat had its last ride for the season and will be pulled out next week.

Can someone tell me what would cause the temp to do this? Impeller? Blocked intakes (zebra mussels are a problem here)

Thanks to anyone who helps

 

[shaw520]

I think you nailed it in your last sentence,... change out impeller.

 

[HT32BSX115]

Same thing. Started fine temp stayed fine until I reached main lake and temp did same thing when I Layed onto the throttle went quickly to 220...i layed off to mid throttle and temp went back down.



Can someone tell me what would cause the temp to do this? Impeller? Blocked intakes (zebra mussels are a problem here)

Thanks to anyone who helps

Howdy,

if an engine temp climbs when you increase power, it's likely you have insufficient cooling water flow (bad impeller, plugged connecting hoses, plugged block, heads, manifolds risers etc)

If you have a problem with cooling system blockage, (debris or Zebris) you need to clear out all the blocking material.

If you haven't checked the impeller in 3 years, you need to change it and if its disintegrated, you need to find the fragments. (chances are the fragments are all pumped down stream and may be blocking someplace (along with the cooked zebra mussels etc)

If you haven't re-installed the thermostat, RE-install it........ DO NOT run without it. The engine will run WAY too cold........

Find the cooling system blockage and you will solve the problem.

Cheers,

Rick

 

[QBhoy]

Yeah...as above...also maybe worth checking the exhaust flappers aren't broken up and jamming up the cooling water flow out the exhaust.