Adding temp gauge to 1970 Merc 800

[Moody Blue]

Can I do it?

Don't see a way of getting the signal wire thru the existing harness.

Found a threaded port on the water jacket cover between #2 and #3 cylinders. Currently has s plug installed. Is this the right place to install the sending unit?

 

[Chris1956]

Re: Adding temp gauge to 1970 Merc 800

Moody, Most inline Mercs do not have a thermostat. Therefore temperature gauges are useless since they show cold at low speed and hot at high speed. A better choice is a water pressure gauge.

BTW- You may use the threaded plug on the head for either gauge. The wiring or tubing will need to be pulled along one of the control cables.

 

[Moody Blue]

Re: Adding temp gauge to 1970 Merc 800

Chris thanks for that advice. Have never seen, or noticed a water pressure gauge. I like the concept though.

Would the pickup be taken from the same place as the temp sending unit?

 

[Chris1956]

Re: Adding temp gauge to 1970 Merc 800

That plug on the water jacket is ideal for the water pressure gauge fitting. You can also tee it into the tell tale, if you cannot get the plug out.

 

[Moody Blue]

Re: Adding temp gauge to 1970 Merc 800

Good thought on the telltale.

Shopping for the gauge but not sure what pressure range I will need. Many are 0-30PSI but others are rated higher. Don't want a gauge where the needle barely moves off the peg.

 

[TheWoodCrafter]

Re: Adding temp gauge to 1970 Merc 800

If you have a manual for the motor (and everyone should have one) you should be able to find the correct pressure that the manufacturer says it should have with a new impeller.