Temp gauge reading 210

[IS-217]

Hi everyone.
2008 starcraft i/o
4.3l mercruiser

My temp gauge is reading around 210F.
There is no alarm sounding. Risers feel cool to touch while motor is running. Water feels like its flowing well through all pipes.
I recently installed a new impeller ran it on the muffs before the lake and water was flowing very well out the exhaust.
I also installed a new thermostat and while i was at it a new temp sensor and a new temp sender as i already had the thermostat housing off i figured i may as well as everything was still original.
Reason for new impeller and seals was because there was some water in the gear oil in the fall.
Reason for the new thermostat was because the boat temp gauge was reading around 130 last summer so i figured maybe the thermostat was stuck open. While i had it off i replaced the sensors as well incase they were the problem with low temp readings.
So im leaning towards a faulty temp sender because the gauge is reading around 210 now but there are no alarms and the engine doesnt feel super hot.
Parts used:
Impeller and new seals - quicksilver
Thermostat - quicksilver 160F
Temp sender and sensor - cheap aftermarket…..

Another reason im leaning towards a faulty temp sender because it is an after market part.

What do you think.
What can i do to test a bad sender.
I dont have a heat reading gun to check if the thermostat housing is matching the sender reading. And im not sure how to test sensor ohms with volt meter.
Im thinking of just swopping out the new sender with the original and seeing if temp gauge reads less. If so ill order OEM and replace.
Otherwise boat feels and runs good.
Used it all weekend with no alarms. Boat gauge consistently read around 210.

Any help/advice is appreciated.

 

[Kola16]

What can i do to test a bad sender.
I dont have a heat reading gun.

The guns are like $20. Easiest thing would be to get one of those. That is what I would do.

You could also put the original temp sender back on and see what it reads though.

I assume this is fresh water cooled?

 

[IS-217]

The guns are like $20. Easiest thing would be to get one of those. That is what I would do.

You could also put the original temp sender back on and see what it reads though.

I assume this is fresh water cooled?

Hey thanks for the reply.
Yes fresh water cooled. Never in salt water. Im the second owner. Bought it from a friend. Hes always taken good care of it. Never had any big problems.

 

[cyclops222]

You changed TOO MANY parts at once !!!!!!
Now you will put back the original parts. Check temperature with $25 Harbor Freight red dot laser gun. See if 200 is still there. Change 1 PART AT A TIME. Then decide who is bad.

 

[IS-217]

You changed TOO MANY parts at once !!!!!!
Now you will put back the original parts. Check temperature with $25 Harbor Freight red dot laser gun. See if 200 is still there. Change 1 PART AT A TIME. Then decide who is bad.

Ok. I get it. Lol. Thought i was being smart changing the sensors while i had the thermostat housing removed.
I figured since no alarm turned on it must be the sender. If it was really running at 210 wouldn't the sensor read that and trigger an alarm? The sender just gives the temp reading to the temp gauge right?
But yes you are right. I shouldn't have changed so many things at once. The original problem was most likely the thermostat stuck open. It was pretty rusted when I replaced it. Maybe the sensors are fine. You think i should put both the original sensors back in?
I looked up a temp gun i think ill buy one. Would be good to have in my boat tool kit. Sounds like a handy tool to own.

 

[Scott06]

Ok. I get it. Lol. Thought i was being smart changing the sensors while i had the thermostat housing removed.
I figured since no alarm turned on it must be the sender. If it was really running at 210 wouldn't the sensor read that and trigger an alarm? The sender just gives the temp reading to the temp gauge right?
But yes you are right. I shouldn't have changed so many things at once. The original problem was most likely the thermostat stuck open. It was pretty rusted when I replaced it. Maybe the sensors are fine. You think i should put both the original sensors back in?
I looked up a temp gun i think ill buy one. Would be good to have in my boat tool kit. Sounds like a handy tool to own.

did you use a gasket with the rivets in it for the thermostat housing ? This it o create a good ground between housing and block.

If the alarm is not sounding you probably are cool enough. Use and IR gun but if you can touch it briefly its not 200f , 180F is about the hottest you can leave your hand on for a brief second.

Also make sure the ohm range on sender matches the ohms range on gauge.