Temperature mystery...

[Tyroma]

Hey gang...

So I am still plugging away at my M37. I got a 0-60 oil pressure sending unit last week (...I had a 0-120 with a 0-60 guage...) and installed that. So now I know that I have 20-30lb at idle at 55lb at highway speed...phew!

I also installed a new temperature sending unit, as the guage has never worked. Well, the guage still doesn't work. What's the easiest way to check to see if the guage is the problem? Is there a common problem with these gauges that I need to look for?

I just put a BRAND NEW rad into my truck, so I don't think that overheating is going to be an issue, but I'd still love to know what the operating temp is.

thanks

Ty

[cuz]

Hello Ty,

The M series gauges like to have good grounds. These are usually a problem in old military vehicles with 5 or 6 coats of paint and fresh restos with a very good paint job and few bare metal star washered grounds.

Start with making sure the engine/frame/body are well grounded together. Make sure the large ground straps are installed. Make sure the gauge is well grounded to instrument cluster and the instrument cluster is well grounded to the dash. If you don't want to scrape a lot of bare metal for the these things to contact then run a set of 16 gauge ground wires from each gauge's mounting bracket studs to the firewall. For example run one wire from the top right gauge's mountins stud to the bottom right gauge. Then one from the bottom right gauge to the bottom left gauge then from the bottom left gauge to the top left gauge and finally from the top left gauge to the firewall.

With good grounds assured then just follow the simple troubleshooting steps in this M series instrument troubleshooting guide: http://www.cj3a.info/sibling/milgauge/milgage.htm

[M37UK]

The first thing I would check is continuity in the wire from the sender to the guage.
If this is ok then you can pull the sender out and do a resistance test on it with a suitable multimeter.
I checked mine this way by pouring boiling water over the end of the sender while watching the meter.
I cant remember the resistance values off the top of my head but I'm sure this has been discussed before on this forum.

If that all appears ok I would suggest the guage is faulty. Make sure the guage gets a good earth as that can cause problems also.

Hope this helps

Stu