Temperature sender for Mercury 500 1973

[knouse94]

Not sure which one I need to buy.

 

[Chris1956]

Re: Temperature sender for Mercury 500 1973

Not worth installing one on that motor. Those motors do not have thermostats, so they run dead cold at idle and warmer at cruise. The gauge will not register until you are overheating.

Buy a water pressure gauge (0-30PSI scale) instead. That will tell you when you are about to overheat, because your water pump has failed.

 

[knouse94]

Re: Temperature sender for Mercury 500 1973

Thank you, how do I install a water pressure gauge?

 

[Maxz695]

Re: Temperature sender for Mercury 500 1973

just get the Temp pessure sensor instead of electric temp sensor. it works on PSI the electric one work by sensing heat like a thermostat you will need a water PSI gage and hose with that same proincipal as an older speedometer works on water pressure. It,s much more reliable

 

[Chris1956]

Re: Temperature sender for Mercury 500 1973

Max, The majority of the water pressure gauges are mechanical. He needs to run a tube from the gauge to the motor. Look for an unused tapped plug on the water jacket cover over the head. Some motors have one some don't. If no unused plug, remove the telltale elbow. Install a brass tee in it's place and connect the gauge to one side of the tee and the telltale to the other side of the tee.

 

[knouse94]

Re: Temperature sender for Mercury 500 1973

Thank you Chris I appreciate the information.

 

[knouse94]

Re: Temperature sender for Mercury 500 1973

It appears that someone has taped a 3/8" hole in between the lower 2 cylinders on the water jacket. There is a plug in the hole right now. Would that be the place for me to mount an elbow or tee? Thanks

 

[Chris1956]

Re: Temperature sender for Mercury 500 1973

That will work. A higher port is better for the telltale however.

 

[knouse94]

Re: Temperature sender for Mercury 500 1973

Thank you for all the info Chris, I appreciate it.