Johnson 70 H.P. temperature

[iggyw1]

Hi guys,

I just picked up a 1982 70 H.P. Johnson motor, model # J70 ELCNB. Seems to run perfect when I took it out on first two fishing trips. The water pisser is working great too. My question: I installed a water temp gage in the dashboard with a sending unit on the outside of the head cylinder cover. The gage is reading a constant high temp of 176 degrees. It has never gone over that. Just wondering what the temperature should actually be in this motor? I know thermostats are set to open at a certain temperature. Does anyone know at what temp this stat should open in this motor? Thanks.
NOTE: My next time out, I know to check the temperature with a lazer temp gun, which I do have now, but if its still in the 175 degree range, is this normal or too high?

 

[racerone]

On a " new to you motor " you should install a new impeller.

 

[iggyw1]

I was thinking about that for sure. Our season here in mich is just about finished, and I planned on doing that during the off season (two more weeks or so).

edit: Does anyone know what the temperature is suppose to be on this particular motor?? I cannot find this info out where I looked on line. I cannot even find the thermostat working temps anywhere either.

 

[racerone]

You should install a new impeller now.-----I have run into many owners who have said ---" I just bought the motor and after 2 trips it overheated "------Often it is then too late to salvage the motor.----Have you tested the " overheat horn " found in the control box ?

 

[Bosunsmate]

Temp should drop when you increase rpm as the poppet valve opens,
My boat alarm goes off by about 176, its a 1982 60hp and has a different thermostat but the same overheat sensor as you.
Id test the overheat horn as suggest by Racerone. Short the tan wire to an engine ground while key is on- theres a sleeve on the tan wire which when slid back reveals a bare connection to use to short to ground.
Itd also depend on where you located your sender too.
Is it at the very top? did you use a z bracket? Did you use thermal grease to conduct the heat?

 

[iggyw1]

Temp should drop when you increase rpm as the poppet valve opens,
My boat alarm goes off by about 176, its a 1982 60hp and has a different thermostat but the same overheat sensor as you.
Id test the overheat horn as suggest by Racerone. Short the tan wire to an engine ground while key is on- theres a sleeve on the tan wire which when slid back reveals a bare connection to use to short to ground.
Itd also depend on where you located your sender too.
Is it at the very top? did you use a z bracket? Did you use thermal grease to conduct the heat?

The sensor is at the top cylinder head bolt. I used the z bracket to mount it. No thermal grease though. (never even heard of that 'til you mentioned it). I will get some. New impeller is in. Temp still reading about 175-176 on the temp gage/ Heads feel ok to the touch. Not running hot. Good water discharge out of the back of the motor and the pee stream is very strong. Everything must be ok at the temp the gage is showing. If it goes above the indication of 176 (whether or not that is accurate) I know it is getting 'hot'.

 

[Bosunsmate]

I got a small tube at a electronics parts shop the other day. $5.
They call it heat sink compound at that shop. It transfers heat away from the electrical components.
http://www.jaycar.co.nz/productView.asp?ID=NM2010&w=thermal&form=KEYWORD

Its much cheaper than getting it from a automotive parts place.
I asked permatex and their tech responded that all their products are insulating so arent suitable for the task.
Yes i agree just make sure it doesnt get hotter. Sometimes i wish i had installed one of those temp guages which can open/shut circuits at a certain temp that way you dont have to keep an eye on the guage, but the only ones i could find at the time were mechanical senders so much harder to install