Engine Temp Gage M 25 XP

[Shadowfax]

OK, my engine temperature gage hasn't really worked in awhile, so in a maintenance frenzy I decided to fix it. I took the wire off the sending unit and grounded it and the gage went to below 0 degrees. I took this to mean that the gage itself worked. I replaced the sending unit, but to no avail.

Logic demands that either the wire is bad [doubt here], or the gage is in fact bad. I'll redo the wire connection at the sending unit just to be sure, but if that doesn't do it, I'm wondering if any replacement temperature gage will do it, or does the new temperature gage have to match the sending unit. I believe the stock Ericson gage was a Teleflex, please correct me if I am wrong. If this is the case does anyone know the correct gage that matches the Universal
M25 XP sending unit.

Thanks

 

[Glyn Judson]

Temp gague won't work.

Paul, Let's hope you didn't do the bonehead thing I did on a friends A-4. The sending unit was faulty, proven just as you did by shorting the wire from it to ground and watching the gague respond. So we bought a new sending unit and I installed it, the gague still wouldn't work. What the heck? Doh.... I'd sealed the threads with Teflon tape, an electrical INSULATOR!!! We removed the tape, got a good ground, used tried and true pipe dope and everything was good with the world. Glyn Judson, E31 hull #44, Marina del Rey, CA.

 

[Shadowfax]

HAH!!

I was told by the dealer that Teflon tape was OK to use, so I did. Off it comes and we'll see what happens.

 

[newgringo]

Calibrate it too

Went thru this drill with my M25, should be the same as M25XP. Mine worked OK but read too high a temp as checked with an hand held optical temperature scanner. Was able to add some resistance and make the thing read pretty close. FWIW the sender resistance in mine is:
080 Degrees 652 Ohms
100 Degrees 405 Ohms
120 Degrees 270 Ohms
140 Degrees 184 Ohms
160 Degrees 135 Ohms
170 Degrees 116 Ohms
180 Degrees 095 Ohms
190 Degrees 088 Ohms
200 Degrees 076 Ohms

A short circuit should peg the gauge and an open circuit should not budge the display.

 

[Shadowfax]

Turns out I will not get to the boat this weekend so I can't try removing the Teflon tape to see if that is the root problem. My basic question is what brand, model, etc., temp gage goes with the stock sending unit, or all they all on the same program?

If anyone knows it would be a great help if the Teflon removal doesn't do the trick

 

[Mort Fligelman]

Replacement Temp Gauge E-35III

I replaced both the Gauge and the sending unit on my M-25 1987 E-35III. I was told to D E F I N I T L Y not use teflon tape......the new gauge shows only a very minimal temp while at idle.....but once under load comes right up to the 160 Degrees.....and with a 160 thermostat.....no complaints....as long as you can get a 12 volt reading at the wire.....best to replace both items.....age is something that you just can't get around.....FWIW

Mort Fligelman
1987 E-35III
Acapella - Boca Raton, FL