1978 85 hp temp sending question

[FISHnGARY]

I was looking into hooking up a temp gauge and thought i had it all figured out until I realized that the sending unit is threaded but where I'm supposed to install it isn't. I've looked it up in the manual so i know that's where it's supposed to go it's just that the darn hole isn't threaded. Any suggestions? 1978 evinrude 85 hp 85899c.


thanks

 

[emdsapmgr]

Re: 1978 85 hp temp sending question

Newer engines have the threaded hole for the sender. Yours does not. Suggest you make an "L" shaped bracket to mount the sender. Remove on of the bolts on the head, and bolt the bracket to the head. Bolt the sender so that it's end touches the head. It should work fine.

 

[FISHnGARY]

Re: 1978 85 hp temp sending question

Thanks for the help I appreciate it.

 

[Joe Reeves]

Re: 1978 85 hp temp sending question

Actually having the sender touch the head (sometimes) results in a false reading. I've found that setting a .010 clearance between the head and the sender cures that problem.

The "L" bracket is part number 122787, available thru your Evinrude or Johnson dealership.

 

[Dennisanoka]

Re: 1978 85 hp temp sending question

If you're a computer geek you might have some thermal compound around. I added that between the head and the sender. It's just that white paste stuff that's used between a PC's processor and it's heat sink.

 

[FISHnGARY]

Re: 1978 85 hp temp sending question

Thanks for the help guys, From doing research I've found that they actually made a temp sending unit for this model of motor, but it looks as though it came with something in the form of a rubber grommet to keep it in place. I mean there is actually a place on the motor to insert the sender. Now I may be making a mountain out of a molehill but I tend to strive for perfection, so my question is does Evinrude make this, or is it a discontinued part leaving me with no choice but to improvise with the suggestions posted? Once again thanks for all of the help. I've added some pictures to show you guys what I'm talking about.

 

[Joe Reeves]

Re: 1978 85 hp temp sending question

That something in the form of a rubber grommet and the picture shown pertains to the old temperature controled choke setup that was discarded by OMC shortly after its introduction. It does not serve any other purpose. Forget about it.

The only setup used for a temperature gauge on that engine (and many others) is exactly what we've told you..... the head bolt and "L" bracket setup.

If you want the advice of technicians that have been in the field for many years and have been there so to speak, and know what they're speaking of, this iis the site to visit. Listen to us.

 

[Silvertip]

Re: 1978 85 hp temp sending question

Not only do you have an issue with the sender, but you might have an issue with the gauge as well. Senders and gauges must be compatible. Some gauges are calibrated C-N-H (cold-normal-hot), others are 60-220, and still others are 100-220 (or 240) and still others are 120-240. The ideal guage (but there are few around any more) are the 60-220 style. Since outboards tend to run cooler a guage with 120 degree cold calibration will hardly register much of the time. The sender is a temperature sensitive resistor meaning that it changes resistance as temperature changes. Hence it must match the gauge calibration. Teleflex has a very descriptive FAQ about this problem. In your situation, I would install the sender on a fabricated bracket that mounts under a head bolt and that positions the sender as close to the spark plug on the top cylinder (both banks on a "V" engine). You can use a switch to switch between the two senders.