Fixing Temperature Gauge on Universal m25xp

[dustintodd]

My temperature gauge is busted, was busted all last summer. Promised myself this would be resolved before I go back in the water. Does anyone have a link to a good article on the trouble shooting steps to be find the problem? I have never looked at this part of the diesel system and have no idea how it works. Any pointers are greatly appreciated. I googled around but the search terms are so generic I get lots of none relevant hits.

- Dustin

 

[Loren Beach]

If you do not have the shop manual for reference, I believe that there is a copy on line at the Torresen (sp) site.
http://www.marinedieseldirect.com/universal/200157/universal-owners-manual-m25xp-specifications.html
I am not sure if it is on line, but the Universal parts manual would be more helpful yet.

First, I would want to follow the wires, check all connections, and basically make sure that everything is where it should be and electrically solid.
If still no joy, perhaps some new parts are needed.

OTOH, if you mean "busted" as in physically smashed, then put in a new gauge in the engine panel. I do not know how to trouble-shoot the sender unit, but would guess that those things have a life span, too.

Let us know how it goes. I believe that a lot of other owners have the same engine as you.

Best,
Loren

 

[dustintodd]

Using a multi-meter t-shoot the sender

Anyone aware of a way to troubleshoot the sender using a multimeter?

- Dustin

 

[newgringo]

Temp Sender Resistance

These Senders are thermisters and have a negative temperature coeeficient.
Here is the values I measures on a new sender for our M25.
Deg F Ohms
80 652
100 405
120 270
140 184
160 135
180 95
200 76
210 69

These compared sort of close to the old sender I replaced. Good luck. It really is not too complicated. I use a fixed resistor to check my guage when in doubt.

 

[Mort Fligelman]

Temp Gauge

Dustin:

My simple fix on my M25:-

Simple voltmeter test across leads on the gauge....if twelve volts there, test the sender.....if 12 volts there.......replace both the gauge and the sender....

Thats what I did..... Worked for me....

Just to make sure that the entire system was A-OK I also replaced the thermostat....160 degrees.....thats what it runs at under load.....the gauge will barely register at sustained idle.....

Hope this helps......

Just to take it one step further I also did Tom Metzgers wiring midification, and replaced the ameter....

 

[Tom Metzger]

Here is Teleflex troubleshooting info from Jamestown Distributors:

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

The manufacturer's info is always more reliable than trusting what you pick up on the web. It generally avoids typos, and other gremlins that sneak in.

 

[mherrcat]

Nigel Calder's book on diesel engines also has a section on testing the temp gauge; basically the same short/open test mentioned in the above link. To test the sender you will need a multimeter to measure the resistance at different temps. Checking the thermostat is a good call. I discovered that the wrong thermostat had been installed in my engine. It was too small and just let coolant flow around it, negating its function altogether.

 

[Shadowfax]

I went through this on my 34 awhile back. I needed a new gage as it turned out do I bought a Teleflex, hooked it up and it didn't work right. Played with it for awhile and came to find that the original sending unit didn't match the new gage ohms wise. Replaced the sending unit with a matching Teleflex sending unit and it now works fine. This in case you need to replace one of the units; replace both.