Temperature gauge for Mercury inline 6?

[DirtyOldBoat]

I'm putting together a "1973" Mercury 1500 with a new powerhead and a bunch of new parts. I'd like to have a temperature gauge to help protect my investment. (along with a new tach, water pressure gauge, and hour meter) Where would I install a sending unit for the temp gauge? Is this even possible?

 

[mercurymang]

Re: Temperature gauge for Mercury inline 6?

I just installed one in my '75 650. There was a port that a 1/8npt brass cap in it. The new sending unit just screwed right in. Do you have anything like that on your block. Mine was between the #1 and #2 spark plug.

 

[Faztbullet]

Re: Temperature gauge for Mercury inline 6?

The way the cooling system is designed on a inline a standard gauge will not read it, better to install 0-15psi pressure gauge as planned...

 

[Chris1956]

Re: Temperature gauge for Mercury inline 6?

DOB, To elaborate on Fazt's message. Since that motor doesn't have a thermostat, the temperature will be dead cold most of the time.

 

[DirtyOldBoat]

Re: Temperature gauge for Mercury inline 6?

Aren't these motors known for cooling issues with the top 2 cylinders? If so wouldn't it be a good idea to monitor the temperature of them? I just picked up a parts motor that had a meltdown in the top cylinder and it scares me! :embarassed:

 

[Chris1956]

Re: Temperature gauge for Mercury inline 6?

Actually, cylinder 3 melts down first, followed by cylinder 1. A temp gauge will show normal, actually cold, until the motor seizes. Shortly before that, the temp gauge will peg at hot.

Just watch the pressure gauge and keep the impeller in good shape. Don't suck up any sand, don't overload the boat and you will be fine.