Finding parts for early versions of equipment has been a challenge. Improvements to equipment results in the old part being removed from inventory and the new parts being stocked. For my M101 made in 1953 (coincidentally the same year as the truck) it did not come with service brake levers, and it appears they were removed quite a long time ago. The previous owner had purchased M101 levers, but they are the newer improved type, and the bracket did not fit, and even if it did would not engage the brake cable correctly.
After some extensive research I found the brake lever type and a source for the handles, but not the brackets they mount to. I got the handles from http://powderriverordnance.com – who has an interesting selection of parts and manuals. The brackets simply couldn’t be found, but I asked a local machine shop if they could make one from photos and the trailer and they stated they could. The staff at http://meridenmachineshop.com / http://www.randsmaintenance.com were very helpful and did a very high quality job making and fitting the parts.
M101 Trailer, early style, brake levers installed
I’ll have to adjust the brakes now, since the cables aren’t set, and then test it, but I know the levers on the drums work from when I serviced the wheel hubs and the levers/cables work so I just have to tension them appropriately now. Once that it done, I can park and disconnect this trailer safely without fear of it rolling away. I have read that these levers tend to pinch your hand, which may be why they were replaced, so I’ll have to wear gloves when operating them which isn’t really a bad idea in any case when disconnecting the trailer.
I have the later style M101 brake levers if someone needs that type, I cannot use them with my setup.
is to blow the engine. After nearly 70 years, the engine finally gave up, breaking the crankshaft and breaking a piston. Fortunately, the block appears to be ok.
M37 Crankshaft
Since this is a major repair, I am going to take this opportunity to replace all worn parts in the engine and transmission, hopefully getting another 70 years out of it. Ill detail the costs and parts list associated with this in case anyone is considering a major overhaul for their M37.
This engine lacked power but started and ran well for about 750 miles that I drove it. It suddenly started making a loud clunking sound on a trip which caused me to shut it off and start looking for a way to get it repaired.
At least when it’s done I should resolve that rear main oil leak that has been bugging me.
After completing this project my truck went from having a variable, but not overheated temp, to stable. The heater works too, just in time for summer. I don’t think I will use acid routinely, but it seemed very effective for use every few years. The procedure I used is below.
TM 9-2320-212-20
9/16 in wrench(s)
1/2 in wrench(s)
Screwdrivers
Water distribution tube
Thermostat gasket (there are two, the housing base gasket, and the top of the thermostat has one inside the thermostat housing)
Bypass elbow gasket
Water pump gasket
Hoses/Belt if you need to replace those, I did in this project
2 ½ -5 lb Oxalic acid (2 ½ lb per flush)
2 ½ lb Washing soda (sodium carbonate)
2 ½ lb Borax
1. Drain the coolant using the drain cocks – Open the one on the front of the radiator first, to capture as much coolant as possible to reuse or dispose of properly. After its clear, open the drain on the engine block (near the oil filler tube) to finish. The drain cock on the engine block was jammed up with gunk on my vehicle, I had to lance it (gently) a few times with stiff wire to get it to drain. You can remove the whole drain cock with a 9/16 wrench to increase flow or clear obstructions.
I recovered the coolant, filtering it through a colander/tee shirt since it is less than a year old. Letting it sit a few hours/overnight lets anything not coolant settle to the bottom to be discarded.
2. Remove the thermostat – This will ensure that any flush cycles through the system without obstruction and is straightforward to do, 2 9/16ths bolts are what holds it on. It takes some maneuvering to remove without gouging the thermostat, TM -20 page 2-118 illustrates this well, removing the bypass elbow simultaneously makes this easier if you have the gasket. For the flush cycles, I reused the old gaskets since minor leaks wont matter at this point.
3. Water Flush – I used a garden hose and set the flow to match the drain rate with the drain cock on the radiator removed, then ran the engine while closely monitoring to ensure the water level stayed full. This forces water to move through the system and exit the bottom of the radiator. I also alternated between radiator drain cock and block drain cock, but did not have the engine running while the block drain cock was open. I did this for about 10 minutes.
4. Acid Flush – I mixed 1 cup (about 8oz) of oxalic acid per gallon, and the cooling system capacity is 4.25 gallon – I mixed 4 gallons of this solution. The TM -20 page 2-116 mentions both aluminum chloride and oxalic acid, I could not find a source of aluminum chloride, nor a reference for its use in corrosion removal. I did find several references to oxalic acid in cooling system maintenance, so I used it by itself. I did 2 cycles of acid flush, driving the vehicle both times to bring up to running temp. Both cycles came out florescent green (much like antifreeze) which appears to be the color of rust dissolved in oxalic acid (ferric oxalate) – Cleaning with Oxalic Acid? Here’s What You Need to Know. – CORECHEM Inc. – All About Ferric Oxalate (bostick-sullivan.com)
5. Water flush – same as 3
6. Soap flush – same as 3 but with detergent (laundry or dishwasher to reduce suds). Not mentioned in the TM, but I have read several internet references on this and I imagine it would be beneficial to remove any oils that somehow remained after the above.
7. Neutralize – Washing soda (sodium carbonate), 8oz per gallon, running to circulate. The TM mentions Borax as an ‘inhibitor’, which I will use second to last flush before adding coolant when finished. Borax isn’t particularly PH basic (PH 9), and am not sure why the TM states to use it, but its cheap and more flushing can’t hurt.
8. Water flush – same as 3
9. Disassemble the cooling system – These steps are to get to the coolant distribution tube, which is apparently liable to get clogged and if it does cools unevenly. Uneven cooling would result in the front cylinder getting adequate cooling and the rear getting less as the water travels down the tube from front to back.
10. Remove tension from the belt – My truck gets belt tension from the alternator, loosening the tension bolt permits the belt to slip of the alternator. Evaluate the belt for replacement, I will replace mine.
11. Remove the fan – its straightforward, using 4 1/2in bolts, this is illustrated on page 2-121. The spacer part will fall out as it isn’t attached to the fan or water pump. Be careful not to gouge the radiator when removing this.
12. Remove the 6 radiator and fan shroud bolts – The bolts on my truck appear to have wire holes to prevent them from turning when installed, but no wire was installed. I used thin boards to support and cushion the radiator when it came loose as the last bolts were removed.
13. Remove the radiator hoses – Page 2-115 illustrates this well, there is the inlet and outlet hose/tubes. Evaluate them for replacement, I will replace mine.
14. Remove the shroud and radiator – Remove the fan shroud being carful not to gouge the radiator, then remove the radiator. It is possible to do this solo, but easier to do with two people.
15. Remove the water pump – there are three 9/16 bolts holding the water pump on, remove these and take off the water pump.
16. Remove/replace the water distribution tube – behind the water pump is the water distribution tube, remove with a tool from Vintage Power Wagons http://www.vintagepowerwagons.com/ (Part #NTP211), I replaced with the Vintage Power Wagon stainless steel tube Part #CC637432. I flushed out the empty water distro tube channel using a hose attachment/wand that got me to the rear of the block to flush things out instead of spraying debris further in.
17. Clean the system surfaces – gasket interfaces, hose connections, and other parts all were thoroughly cleaned (washed and wire wheeled where needed). I spray painted the fan shroud and tubes with black engine paint, and the radiator body (not cooling tubes) with green paint from Army Jeep Parts – Gillespie Coatings Paint | Military Paint | Army Jeep Parts
Painting for corrosion protection
18. Flush the radiator – My radiator overflow pipe (the small tube from filler neck to the bottom of the radiator for overflow fluids to exit) had been clogged, causing coolant to spray all over the engine from time to time. Solving this issue was fairly easy, I used electric fence wire to lance the tube, clear the blockage, then flush it out. The radiator itself benefited from being able to tilt from side to side, dislodging more debris in the bottom and flushing it out with a hose. Use caution and don’t batter the radiator while doing this.
19. Install the radiator and fan shroud – Use thin boards to cushion the radiator as it is placed. I wired my radiator bolts so they wouldn’t loosen, but it seemed fine without it. The bolts are drilled for wire, so it seemed like it should be done. I used electric fence wire, which should be durable and not prone to corrosion as it is made to be in the weather. I have no idea if this tie is correct, but I assume it will prevent the bolt from turning.
Safety wire to prevent bolts from loosening
20. Install water pump – using a thin coat of sealant on both sides of the gasket, replace the water pump and gasket
21. Put the belt in place
22. Install the fan and fan drive pulley, orchestrating all this is tricky with the space available, but possible with patience.
24. Install the thermostat, inlet/outlet hoses, and heater hoses if you have those. The bypass elbow and thermostat housing have to be installed together, there isn’t enough hose between them to maneuver the thermostat in place otherwise.
25. More flush cycles, Borax then water. Check for leaks and test drive.
26. Fill with distilled water and antifreeze and bring to temp to ensure its mixed well
With summer around the corner and remembering that the truck got over thermostat temp when under load on hot days, I decided to do some cooling system maintenance. Thermostat is 180f, but the truck would get to 200f or so under load but come back down when cruising or idling. This, from what I am reading, isn’t terrible but I would rather deal with it before it gets me stuck somewhere.
I purchased some parts from the very helpful staff at Vintage Power Wagons https://www.vintagepowerwagons.com/: Coolant distribution tube that goes in the block behind the water pump, a tool to remove the distro tube, a thermostat, and a radiator cap. I also got 5lb of oxalic acid, which the TM mentions, to flush the system.
The plan was to do a couple cycles of oxalic acid, drive it around for a bit each cycle, and let it sit a couple hours each cycle. I made an assumption that doing this first would make the water distro tube removal easier. Oxalic acid isn’t a particularly vigorous acid, but I was cautious with it, using the recommended safety equipment. The cooling system is a little under 5gal, and the mix is about 8oz per gallon which worked out to use the whole 5lb. The Oxalic acid in water was clear when freshly mixed, but it came out green after the flush cycle –
Not antifreeze
The system was flushed thoroughly with water prior to acid flush, and was clear, so the photo above is the result of the oxalic acid flush. A significant amount of solids flushed out as well.
The system then was thoroughly flushed with water running the engine each time to circulate, then neutralized with washing soda.
After the system was flushed, I moved to the water distro tube, which was not as bad as I thought it would be. I had to remove the radiator, the cooling fan, and water pump which I will detail after I confirm this all works.
Water distribution tube channel visible after water pump removal
Having seen a couple videos on waster distro tube removal, I was anticipating a fight to get it out. A youtube channel Watson’s Wagons detailed his experience with removing it here – Dodge M37 Water Distribution Tube Removal – YouTube. My tube, possibly due to the flush, came out without a slide hammer much to my surprise. I was anticipating the tube to have solder and other garbage jammed in the channels based on a couple examples on youtube, and it did. The rebuild depot for these vehicles must have had a mechanic that loved solder. I pulled about 3 fingernail sized chunks of solder out.
The thermostat also appears stuck partially open, so I am glad I got a replacement. It may just be stuck in this position which would explain its very sluggish coming up to temp and may have contributed to it not keeping up with heat in warm weather along with the accumulated corrosion in the system. The ‘new’ thermostat was amusingly made in 1966 but looks as good as it did when it was made.
Old thermostat on left, new on right
When it’s complete and confirmed working, ill detail the steps I took but at this point the oxalic acid flush seems very effective at removing corrosion and restoring flow to the cooling system.
Given a long weekend, what better thing to do but camp and get on a radio? I selected Shawnee State Fishing Lake near Topeka, KS since it is open year-round like Nebo. Winter field day in January was chilly, but fairly nice, but this trip really tested the gear. High winds the first day and snow the second into the third.
High winds batter the setup the first dayHail, followed by snow day two and three
This trip I was able to make the highest number of contacts since starting POTA, with over 150 in a day, plus several ‘Park to Park’ contacts where contact is made with other people at POTA parks. I am getting more efficient at copying/logging, but I also had help from my son who joined me for this trip.
Operating the station
Getting out of the park would have been tough in a regular vehicle, there are some steep inclines and I had to put the truck in 4WD. Once I did, it easily got through the mud and snow.
When the weather gets warmer, I do want to detail the DX Commander antenna while making some improvements to it. It managed the high winds well and, as always, got good reach on the air. I also want to detail some work on the M37, bearing maintenance, brakes, and cooling system as I service those items for 2022. I also need to find some way of adapting or making an antenna for the truck itself on VHF Amateur radio that looks similar to the military antenna on it now.
The weather couldn’t have been better with mid 40s in the daytime at Nebo State Fishing Lake, the location for our WFD22 camp. Amusingly, our first contact was someone very close to us, in the vicinity of Holton, KS and we likely picked them up on groundwave. We spent the majority of the time hunting people calling CQ, which slowed us down considerably, but we made around 80 contacts in this way. The M37 and trailer worked beautifully, fresh out of the garage after servicing all 6 wheel hubs. My two sons joined us for a bit and operated a couple contacts, and a fellow amateur operator joined for the whole trip.
WFD22 Camp at Nebo State Fishing Lake
My Duracell Gel lead acid batteries are shot so we had to use the generator (a Honda eu2200i) on this trip, but it did not cause interference and it is very quiet. I am pretty disappointed with the Duracells, I will have to try LiFePo (Lithium Iron Phosphate) batteries at some point. I am very happy with the generator, very easy to maintain and appears to be very reliable.
I also continue to be very happy with the DX Commander antenna, very easy to setup and it has proven to be rugged. I can easily set it up solo but having help of course is welcome. I cut the elements for data frequencies, so I did use a tuner for voice operations, but it didn’t seem to hurt performance.
DX Commander on the lake levy
I really enjoy the WFD events and camping next to the frozen lake made for some beautiful scenery. Our score won’t be spectacular, but just getting out to a campsite and enjoying operating radio made the trip a lot of fun. Next field day, we will likely try incorporating another radio and antenna and try to double up our throughput, likely one data and one voice station.
One aspect of owning a military vehicle that I find fascinating is the parts you can get. Termed “New Old Stock”, meaning parts that have never been used, but are made several decades ago. I ordered a blackout headlight from Kaiser Willys (https://www.kaiserwillys.com) and received a part made in WWII – September 1944 assuming I am reading the stamp correctly.
Headlight from WWII
Of course I do not anticipate driving in blackout drive often or at all, but I do like for the truck systems to all be working if I can fix them.
When I was on active duty in the 80s-90s I often had to drive in blackout as the doctrine at the time was to operate exclusively at night as we had superiority in night vision. While that may have been true, not everyone had goggles and I spent the majority of time driving with the tiny of sliver of light these blackout headlights provide. While it works, it requires a great deal of attention and is fairly nerve racking to do. If you are hiding from aircraft, however, it is very effective at reducing how noticeable you are compared with normal headlights. It was the late 90s since I last saw any unit attempt convoy training at night on any large scale.
This blackout headlight style is an older type, and I am not sure what originally came with a factory M37, but the housing I have fits this type of lamp. The light that came with my truck was dim, and the unit was rusted through. These types of headlights are sealed units, the bulb cannot (easily) be replaced, the bulb and outer glass is press fit into the housing meaning the whole thing is replaced normally.
Since my original was rusted through and mostly ruined anyway, I forced the housing apart with a screwdriver and will see if I can adapt some 12v LED in the housing at some point later if the bulbs become difficult to get.
With the buck converter the lamp appears as bright as I remember them being from my time on active duty. The buck converter easily fits in the blackout headlight housing, even after putting some padding on it. If I ever have an occasion to use the blackout drive, it will at least be serviceable.
With Veterans Day weekend being a long weekend, it was a great opportunity to take the setup out and operating. I have a M101 trailer that came with the truck, but it is in the garage for bumper number painting and services to the hand brakes. The M37 held everything I needed, although the trailer is nice to have for bulk items like firewood and fuel cans, for this trip I had to get creative with the load plan.
Summarized inventory was Honda 2200i generator, 2 70ah Duracel Gel batteries, power distribution case, Icom IC7200 radio, DX Commander antenna, Raspberry Pi, and old Surface 3 for display.
I arrived in the afternoon and set up the tent with daylight, but by the time I got to the antenna it was dark. The DX commander is easy enough to deal with that I was able to get it set up in moonlight. I did modify it a bit, the longer elements, 80m and 40m, have clips attached to them so I don’t have to run them through the spacer plates. This isn’t perfected yet, but the basic idea is shock cord, shrink tubing, and a little glue to hold the clip in place. I set them to low so the elements move around too much, but improving the placement will make these nearly as good as intended design while greatly speeding setup and teardowwn. I also intend to add shock cord on the bottom of the element to reduce stress on the spade clips at the feed point. Once I get a final arrangement, I will detail this.
After getting setup, it was dark, so I listened to shortwave for a bit then got some sleep. In the morning, it was very cloudy so I had no solar. I decided to try a concept where I run the generator and connect a battery charger to the batteries and operate the radio. This did not work at all, at least with the charger I have. I do have an AC power supply, but having never needed it before, I generally don’t bring it. My daughter rescued my trip by delivering this power supply to my campsite. I have avoided using a generator previously as I have seen generators create interference on the radio set. Having no choice, I started the Honda 2200i and was pleasantly surprised to find it did not interfere at all. While I prefer using the solar when conditions are right, its nice to have an alternative for cloudy days and night operations. I have run this generator briefly before, but this is the first time I have used it for extended periods. It takes about a gallon of fuel for an 8 hour run, and appears to be very steady. It is also exceptionally quiet audibly. The generator was not specifically purchased for camping, but to power critical items during power outages at our home, but since it works well ill make this a regular item along with the AC power supply. I ended up using the generator for the entire trip.
Radio Station
I used a program called HAMRS (https://www.hamrs.app/) for logging this trip. Previous trips I have used paper logs and transferred these to a log format to submit, but this is very tedious. I also likely did not format the logs correctly as it did not capture some elements like park to park contacts in these manual attempts. HAMRS was easy to use and I think I will keep using it. One thing I will change is where I am using it, I set it up on my Raspberry Pi and it could not keep up, which slowed the rate I could make contacts. When clicking ‘save’, it took about 20-30 seconds before I could type a new contact. In testing, using HAMRS on the display computer, a Surface 3, it responded right away so that is where I will run it in the future.
The M1950 stove is great, but is fussy with wood fires. I have to wake up every couple hours to feed it or the fire gets too low to restart easily. I have had problems with overheating, since the door of the stove does not seal well, but I have found that moving the fuel to the rear of the stove helps slow the fire down enough to be manageable. It is easy to cook on, however, this trip I had 15 bean soup, powdered eggs, and sausages for main meals, as well as a constant supply of coffee and tea. It is supposed to burn coal according to the TM, but anthracite coal wont burn in it as it is, so at some point I’ll have to see if I can get bitumen coal and try that.
I am very happy with my setup, the truck is fun to drive and my setup is, or nearly, complete. I think Lithium iron phosphate (LiFePO4) batteries would still be very nice as they cycle (discharge/charge) much better than lead acid, and being lighter would be nice. With winter nearing, I should be heading out more often for POTA trips and getting more contracts with my setup. This trip I made about 220 total contacts, much higher than my previous attempts.
This is likely overkill, but it is fun. The M37 is a military vehicle introduced in the 1950s to replace the WWII era WC 3/4 ton trucks. It is larger than a Jeep, smaller than a 2 1/2 ton, all my radio and camping equipment fits easily inside. I was able to take it to Lake Perry State Park for a parks on the air activity September 2021. I was looking at various recreational vehicles to move radio equipment, but none of those would be as interesting as this truck. The truck has many features that I will have to detail, particularly the antenna and mount that seems to tune from 30-50Mhz which is what I would expect for a military antenna.
This trip I was able to use the DX Commander antenna, which performed very well giving me 141 contacts in a weekend. With cooler weather nearing, I expect to get in the field more often since I find winter camping more comfortable than summer camping. I made some modifications to the antenna to speed up setup and tear down which I plan to detail soon.
