M38 24V SW Temp Gauge screw-up

arisLgr · Post by **arisLgr** » Sun Aug 27, 2017 8:59 am

Hi guys, I really screwed up my NOS SW temp gauge! It was working but showing lower than actual temperature, so daft me, to check it I hooked it up straight on to 24 volts and BANG, it died on me!
I'm sure I must have burned it so with replacement prices sky-high, does anyone know of a repair shop for those gauges?

4x4M38 · Post by **4x4M38** » Sun Aug 27, 2017 9:24 am

Aris,
What are the part numbers on the gauge?

How exactly did you wire it to 24 volts?

w30bob · Post by **w30bob** » Sun Aug 27, 2017 9:29 am

Hi Aris,

The plastic lens for these gauges is held on by a "crimped-on" ring and is not intended to be removed. If you can find a way to re-crush the ring you could possible pry the ring up with a screwdriver from the backside and take gauge apart.........but they weren't designed to be taken apart.

Even if you got it apart......if you fried the small wire coil....it's toast. You're only real option is to replace it with another gauge. You see these gauges used at the meets for pretty cheap all the time.

regards,
bob

Post by **wesk** » Sun Aug 27, 2017 3:37 pm

Only the extremely early M38 gauges were 6 volt and used the external 95 Ohm resistor. The rest are 24 volt (having internal resistors) so they are connected directly to 24 volt all the time.

Let us know the actual part number of the gauge you fried.

AC # 1512244, WO# 118105, ORD # 7728855 is the very early M38 MC10001 thru MC17855 units used with the external resistor.

All of these temp gages are with Internal resistors and connect directly to 24 Volt:
AC # 1512422, SW # 505A, WO # 119086, ORD # 7389567 AC # 1512669, SW # 505N, WO # 811244, AC# 1512676, AL # EO-11933, SW # 505K, WO # 808568, WO # 809822, ORD # 7954511.

AC = AC Delco
AL = Autolite
SW = Stewart Warner
ORD = US Army numbering
WO = Willys-Overland numbering.

arisLgr · Post by **arisLgr** » Mon Aug 28, 2017 5:02 am

Thank you all for the replies, the gauge is still on the Jeep and I will be able to remove it in a couple of weeks, at that time I will post it's SN!

4x4M38 · Post by **4x4M38** » Mon Aug 28, 2017 8:06 am

Aris,
The numbers we are asking about are on the face of
the gauge, usually at the bottom, sometimes just below
center, and sometimes at the top.

No need to remove the gauge to find these numbers.

Post by **wesk** » Mon Aug 28, 2017 8:49 am

No need to remove the gauges. The part numbers are on the front (face) of the gauge.

arisLgr · Post by **arisLgr** » Fri Sep 08, 2017 11:21 am

OK here it is

4x4M38 · Post by **4x4M38** » Fri Sep 08, 2017 4:10 pm

That's a 24 volt gauge. It would seem
the only way you could have damaged it
was to reverse the leads.

You might still go through the gauge troubleshooting
procedures just to confirm it's toast.

If you are still in need of a gauge the brethren here
may be able to help.

Take care,

baios · Post by **baios** » Sat Sep 09, 2017 7:27 am

aris baios here any foto of yr m38?

arisLgr · Post by **arisLgr** » Sat Sep 09, 2017 10:25 am

Any links for the gauge troubleshooting?

4x4M38 · Post by **4x4M38** » Sat Sep 09, 2017 10:29 am

Top left, under downloads.

M38 electrical heading.

http://willysmjeeps.com/downloads/instruments.pdf

arisLgr · Post by **arisLgr** » Sat Sep 09, 2017 10:34 am

Thanks a million Brian !

arisLgr · Post by **arisLgr** » Sat Sep 09, 2017 11:01 am

Well, I bench tested the gauge with a D 1,5 volt battery then with a 3,7 volt as well, nothing moving...

so I've burned it

Where do I go from here? I did find a NOS one on line but it was very expensive, This one looks just like new so I wonder if it can be repaired, or maybe I could buy a cheap replacement and use it's innards on mine?

arisLgr · Post by **arisLgr** » Sat Sep 09, 2017 11:09 am

Baio here is the pic