Temp change?

[Fiat4Fun]

Howdy,
I have a 1986 260HP 5.7 with a alpha one. Put a new factory drive on earlier in the year, and the boat has been doing fine. The boat has always kept a low temp reading, like 150-160. Last night I noticed that the temp gauge got up to 180. I also noticed that the two bypass hoses that go from the thermostat to the risers seems cooler than I remembered. Could the thermostat have a issue? Or could this be the old water pump starting to fail? I have been looking for leaks from the
engine, thinking water has been getting into the bilge from a hose, so I will be checking that too.

Any thoughts, would be greatly appreciated. What should the temp be when running? The gauge never went over 180, so I was not overly worried, but hotter than normal in the same lake!
Thanks

 

[alldodge]

Howdy,
I have a 1986 260HP 5.7 with a alpha one. Put a new factory drive on earlier in the year, and the boat has been doing fine. The boat has always kept a low temp reading, like 150-160. Last night I noticed that the temp gauge got up to 180. I also noticed that the two bypass hoses that go from the thermostat to the risers seems cooler than I remembered. Could the thermostat have a issue? Or could this be the old water pump starting to fail? I have been looking for leaks from the
engine, thinking water has been getting into the bilge from a hose, so I will be checking that too.

Any thoughts, would be greatly appreciated. What should the temp be when running? The gauge never went over 180, so I was not overly worried, but hotter than normal in the same lake!
Thanks

Normally your engine should run around the 140 to 160 range. Your thermostat should be a 140 degree and the 160 should only come in when running hard. You mentioned the old impeller, this was a new impeller in your new drive this season correct?

The first thing in most all cases of overheating is the impeller and/or pump housing.

 

[Fiat4Fun]

Thanks for your response. The impeller in the drive is new. The water pump and thermostat in the motor are old!
Hope that helps……..

 

[thumpar]

You can pull the thermostat and put it in a pot of water with a thermometer. Put it on the stove and see what temp the thermostat opens up at.

 

[alldodge]

Thanks for your response. The impeller in the drive is new. The water pump and thermostat in the motor are old!
Hope that helps……..

Agree with thumper but if the thermostat checks out, I would check the new impeller.