Info needed: 1967 M38A1 Lubrication?

[Les Kovacs]

Thanks for temp sending unit info....I will change out with gauge soon.

I just picked up a new 4 lb rad cap from Bay Auto here in Barrie. CDN2 manual states a 4 lb cap.....Kaiser Willy,s only sells a 7 lb cap.

Thanks for carb mixture info....I will adjust soon.

Took the jeep out again today.....+24C/sunny and humid (solar eclipse here in Barrie was a bust....not much change in lighting.) After 15 min driving-temp gauge showed a tick over 180 F....never moved after getting there. On my return home I immediately opened the hood, felt the upper rad hose (no pressure) so I pulled new rad cap and measured coolant temp....as yesterday at 155-160 F.....not sure how to interpret info....bad gauge?....sending unit? or both?

Please comment.

PS...for some reason your picture did not come through?

les

[rob love]

That's funny, I see the photo just fine. Google M-series temperature sending unit and lots of photos of it will come up.

I am sure there is a proper range of ohms that could be compared at various temps for both the gauge and the sending unit, but I can't tell you what they are. In the army, parts were cheap. We would just change whatever half was easiest, and if that didn't work, we would change the other part. A word of caution when working on the panel. It MUST be grounded before you turn on the ignition switch if you have it off the dash, or you will almost instantaneously burn out any or all of the gauges (oil, fuel or temp). Other vehicles like the M151 actually had a ground wire from the body to the dash,the M38a1 did not. The gauge case must be grounded. Too often, guys would test the gauges by putting power to the smooth connector, and ground to the ribbed connector. The needle might move back and forth, but the damage will be done.

[Les Kovacs]

Nope....I do not see any pics....all I see is a small black box in the lower left corner with an X in it. However, I will google it.

Wow...thanks for the word of caution.....can you walk through the changing of any gauge (eg-temp) starting at taking off the panel and grounding....not sure when to ground....the actual changing of the gauge and sending unit sounds and look easy.

Also....I noticed that there is a hex threaded screw on top and at the back of the generator....is this for lubing? I thought that these units are lubed for life?

Again....thanks for the caution....I would have no doubt shorted out all the working gauges and sending units not even knowing what the cause was.

les

[maple_leaf_eh]

Originally Posted by Les Kovacs

...

Wow...thanks for the word of caution.....can you walk through the changing of any gauge (eg-temp) starting at taking off the panel and grounding....not sure when to ground....the actual changing of the gauge and sending unit sounds and look easy.

....

The M-series was designed to be fixed by mortals. If the gauge unbolts and the connection unplugs, that is literally as much work as is required.

BTW, this conversation between you and Rob is worth a Sticky for troubleshooting.

[rob love]

You can change the gauge as Terry describes, but before you turn on the ignition switch, you either have to run a ground to the panel, or else re-install the panel back in place. The best solution is to make up a short wire permanently installed form the dash to the panel.

When installing the gauge, the spide harness (power) goes to the non-ribbed connector of the gauge. The sending unit wire will be ribbed, and goes to the ribbed connector of the gauge. Make sure the retaining bracket is solidly onto the gauge as that is where the gauge gets it's ground.

That little allen key on the back of the alternator is where you can adjust a tiny potentiometer to adjust the alternator's output voltage, should it be too high or low. Some of the alternators (the prestolite AU20003 model if memory serves) also have a terminal inside where you can change the output from 60 amps to 30 amps if you are in hot climates.

[Les Kovacs]

Hi Rob & Terry....thanks for both reply's....I agree with Terry....I am sure that all the questions & responses in this post have been done before.....but probably not all in one place/post....case in point...I have saved all the questions & responses from Rob and et Al in a word document.....when it comes time to actually work on the jeep when parts start arriving....I have the info-details from people that have actually been there as well as following the 3 manuals I bought from Brian Asbury.

OK Rob....another question regarding the shorting of the panel just to confirm...as per you email...."you either have to run a ground to the panel, or else re-install the panel back in place. The best solution is to make up a short wire permanently installed form the dash to the panel."

So, Question....if the panel is off...and you have completed the replacement of the EG: temp gauge & sender you can replace the panel to the dash before you turn the ignition on and you should be golden....correct? It sounds like the bottom line is that you cannot turn on the ignition before you put the panel back on the dash to ground the panel...correct?

les

[hrpearce]

Originally Posted by Les Kovacs

It sounds like the bottom line is that you cannot turn on the ignition before you put the panel back on the dash to ground the panel...correct?

les

That is correct, saves any chance of failure. I would leave the keys on the bench till the work was complete.