1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Hi Folks,

I am in the process of bringing this 70 up to scratch and re-doing some of the things undone by the previous owner.

One of those things is getting the (I believe) OEM temperature gauge to work again.

I have found a (loose and taped) tan wire near the red plug that, when shorted to earth, flicks the gauge up, so the gauge works. Good too, because it's a smart unit.

I also found the stub of a broken bracket under a bolt on top of the engine, which suggests a head temperature sensor has been used a some point, and then snapped off, but this may be wrong.

So, out-of-the-box, did the 70's of this age come with a sensor plug through to the water jacket, or can I make one, or do I use a head sensor? Given a choice I'd measure the water, but not at the risk of drilling holes in the wrong place.

Any and all thoughts very much appreciated.

Also, if I have to buy a sender for the head without recourse to knowing what sender the gauge was intended for, do I get one with the widest resistance band ike 10-312 ohm, or a narrower one, say 23-240? I know that the gauge will probably never read the right temperature again, but I could get used to looking and seeing that the temperature shown, though not right, is 'normal'.

G'day

Low

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Hi Guys,

Teleflex, or VeeThree, as it now seems to be, have part number IA96035 which is a sender specified for pre-1995 Johnson/Evinrude engines and only a 50-250 degree gauge, which is what I have.

I will buy one and let you know if it works!

Check it out here:

http://www.jamestowndistributors.co...bleshooting+Teleflex+Water+Temperature+Gauges

or

http://gfretwell.com/electrical/teleflex senders.pdf

G'day

Low

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

That tan wire does not lead to a "sensor". It's either open or closed. It's only to trigger the overheat buzzer in your control box. It won't feed a gauge. You'll have to find and attach a separate sender for your gauge. Don't ask me what one that is because I failed miserably trying to get the temp function of this cool mulch-function gauge I got to work. I think my my motor was fully engulfed in flames, it may move the needle a little bit :facepalm:

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Hi Ez,

Sorry, my apologies for not being clearer, this is another tan wire, running from the back of the gauge and cable tied to the loom back to the head.

With luck, the sender I've identified above will run my 50-250 gauge as advertised. Is your gauge a 50-250?

But then it is always better to travel in hope - or is it better to arrive.....one or the other.

New manual arrived today, so lots of fun to be had now!

G'day,

Low

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

I am not familiar with a Johnson/Evinrude motor of that vintage that's equipped, from the factory, with a temp gauge sender (I could be wrong). I'd be interested to see where that tan wire leads. My motor has two of those heat switches embedded, one in each head, I believe with a tan wire, and it's just to trigger the overheat buzzer.

My gauge is a 100-240 degrees. I ordered a sender from marineengine.com that attaches via a Z-bracket to one of the head bolts and makes contact with the head. Unfortunately the gauge only moves a tiny bit ever, even if I hold a friggin' lighter to the sender.

This is my awesome multifunction gauge http://i176.photobucket.com/albums/w200/ezmobee/New Boat/IMG_1139.jpg Only the fuel and volts gauges are of any real use. Apparently the trim gauge is for a Mercury and operates in the reverse of an OMC so that read backwards :facepalm:

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Hi Ez,

You are right about the second tan wire not being factory fitted, it's an add-on, cable-tied to the loom. The usual tan wire to the temp switch is also there and works fine.

What I am trying to do is to isolate the correct sender for my gauge without knowing its specified resistance and it is a bit circuitous, but I think I may have done it - like this.

First, my boat is late 70's, so the sensor type will be old. So a sender which says it is designed for a gauge with a temperature range of 50-240 degrees and only pre-1995 engines sounds like it may work when I have a 50-250 degree gauge an an 82 engine.

Then if the sender is also SW matched, which it is, it suggests a broad range of applicatons - the shotgun approach.

I cannot find the Teleflex IA96035 anywhere - to buy that is - I can find plenty of references to it, but no one selling it. Stewart Warner do a match - their SW-280-EC, 100-240 so I am going to go for that on a home made Z-bracket and see what happens.

I'll let you know if it works.

G'day

Low

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Lowengrynn said:

I'll let you know if it works.

Click to expand...

Please do! I'll be interested to see how it works out.

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

No worries. Smart multi-gauge!

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

The best way to match up the proper sender is by Ohm rating. Do you know the manufacturer of your gauge? or can you remove it from the dash and get pictures of the front and rear of it.

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Hi Six,

Thanks for your comments. Much appreciated.

Unfortunately, to get to the back of the gauge requires some bodily dexterity of the like exhibited by small women who can happily get into a suitcase and close the lid. I can lie on my side bretween the seats with my hands above my head and the back of my neck on the footrest for just so long!

What makes the removal of this gauge harder is that it has three white wires seeming to use it as a common terminal as well as the ones you'd expect. They are only just long enough to reach the gauge and I have a horrible feeling that if I loosen them I'll never get them back on again.

I'll take a shot of the front though and post it.

G'day

Low

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Sixmark said:

The best way to match up the proper sender is by Ohm rating. Do you know the manufacturer of your gauge? or can you remove it from the dash and get pictures of the front and rear of it.

Click to expand...

Hi Six,

Attached is a photo of the gauge - no macro I'm afraid so a bit blurred.

No manufacturers name although the tacho and hour meter are both OMC.

The image on the face is a bulb thermometer or similar idea and scale is 50-200 degrees.

G'day

Low

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

It is an old OMC gauge.
Go to:
Shop.evinrude.com
View parts catalog
Accessories
1982
Instruments
Outboard watertemp gauge

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Unreal! Thanks Haffiman!

Low

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

See, now you know why pics are a great tool on the forum. Hope you get it fixed soon.

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Hi Haffiman,

Checked out your link and ordered and fitted the sender for the water temperature gauge for the 1982 model and bingo - water temperature gauge now registering happily - at least moving upwards while on muffs.

Just have to see what happens at speed on water but at least now I am comfortable I will have a 'normal' reading to refer to if not a truly accurate temperature!

Thanks again Haffiman!

G'day

Low

Re: 1982 Johnson 70hp water temperature sender/sensor - answer maybe!

Just be sure you keep all electrical connections between sender and instrument clean. It simply operates by change of Ohm reading (resistance in sender) and corroded connections may alter the readings.
Happy boating!!