Temp gauge and sender unit

[jif102]

I am replacing my temp. sending unit and thermostat in my boat. I have a 1986 Larson with a 228 MCM Mercruiser engine. The engine serial # is 4830267. How can I tell what type of sending unit I have?

I might also change my gauge. It appears that I am not getting a good reading on my engine Temp. The needle hardly moves.

Thanks for the help.

 

[Haut Medoc]

Re: Temp gauge and sender unit

I would change the thermostat first......
& see what (if any) results that yields...
You can look up the part on Bammarine or Doug Russell....
I would check the wiring connections at the gauge & sender to make sure they are clean & tight....
Also the wiring harness plug connection......
You would also want to verify the temp with one of those hand held temp gauges that you can point & get a reading on different parts of the engine.....
To test the gauge, remove the wire from terminal 's' on the ignition switch......
Turn switch to 'run'...
Reading should be '0'...
Connect jumper wire from terminal 'g' to 's' ......
Turn key to 'run'....
The gauge should peg......

 

[Bondo]

Re: Temp gauge and sender unit

Ayuh,....... I Agree with Haut,.......

You can also Check the Wiring by Grounding out the terminal to the Sending Unit, It should Peg the Gauge......
And,.........
Make Sure the Base of the Sending Unit has a Good Ground,......
The Sending Unit can be Tested with a Multi-meter,......
There's Low ohms on a Cold unit,+ More ohms as it is Heated.........

Figuring out What is Wrong,.... Is Better than Just Throwing Parts at It.........