Tech Tips

Beware Of Asbestos

Many vintage HMVs still have clutch disks made with asbestos, which can be dangerous if particles are inhaled. It’s wise to wear a dust mask when working on the clutches of older HMV. because asbestos dust may have accumulated inside the clutch housing. The same warning applies to the brake shoes of many vintage military vehicles.

Don’t Get Snappy

Be careful when removing or installing snap rings. They have a nasty habit of flying off and can injure an eye. Whenever possible, use proper snap ring pliers. Wearing safety glasses is a good precaution.

But It Says “160” On The Box

The temperature rating of thermostats (160, 180, 190, etc.) indicates the temperature at which the thermostat starts to open. It does not mean that your engine will necessarily maintain that temperature.

Always carry a new thermostat and gasket, plus the tools to install it, when venturing far from home in your HMV.

Old School Mechanics

Oiling a vehicle seems to be a forgotten practice, but you might be surprised how much longer things like clevis pins, door and hood latches, clutch and brake linkages, hinges, yokes, window crank mechanisms, and glove box buttons will last. Not to mention you. choke, throttle, and fording valve cables. They will all operate smoothly if you get into the habit of putting a few drops of oil on them every month or so.

An occasional drop of oil on the stems of push/pull switches will make them work smoother too. Don’t forget to put on drop on ignition keys, window latches, seat adjusters, wing nuts, thumbscrews, carburetor linkages, and door locks.

Where Did It Go?

I own a 1964 Unimog 404. I was checking the oil levels and found the transmission almost empty. I topped it off six months ago, and there is no oil leaking from under the truck. What could have happened to the oil? Is this a leak that only happens when I’m driving? — Matt

If a Unimog transmission output seal leaks, it doesn’t show externally. It leaks down the inside of the drive shaft tube and overfills the differential.

Don’t Do The Bump

In the category of “things I did before I knew better” was a common shade tree method of removing the nut or bolt from an engine’s crankshaft pulley. I used the method of fitting on a socket and breaker-bar then “bumping” the engine’s starter —until I guessed wrong about an engine’s rotation. Thebreaker bar flew around and crushed the case of the voltage regulator mounted on the fender splash guard.

You have no control over the forces involved when bumping a starter to break something loose, and it’s easy to damage a radiator or something else.

Stopping The Leaks

Most people with experience in vintage HMVs know that the windshields on GPWs, MBs, M37s, M35s, etc. tend to leak in rainy weather. I personally like an opening windshield in warm climates.

After spending a summer around Anchorage, Alaska — one of the rainiest places I’ve ever been — I found a very simple solution to the leaks in my M37’s windshield: Good old American duct tape. I also bought a can of OD spray paint, which covered the silver tape so well that it couldn’t be detected from twenty feet away. It was easy to remove the tape and nice to be able to open the windshields on my homeward journey through Montana, Utah, and Arizona.

A more permanent, though not irreversible solution, is to seal the windshield seams with silicone for the winter. Then, some simple razor-blade work will allow you to open the glass again come spring.

Either of these methods can also be used on the windshield frame-to-cowl gasket.

Should Have Done That A Long Time Ago

Ignition points and condensers for vintage vehicles are becoming harder to find and more expensive these days, especially good-quality items. It got to where it was costing me about $30 to replace the points and condenser on the International 304 engine in my truck, so I finally installed an electronic unit, which simply consists of a sensor taking the place of the points, and a little magnetic ring that fits over the distributor rotor. Other than removing the condenser, there are no modifications to the distributor.

Besides not having to clean, adjust, and replace points and condensers anymore, the results have been faster starting, better engine performance and smoother idling. Another advantage on older vehicles is the sensor isn’t bothered by a worn distributor with a wobbly rotor shaft. Installation is a simple two wire hookup.

If the sensor should fail (they’re reputedly very long-lived) one can reinstall points and condenser, though I bought a backup unit. These kits are available for many older engines and can easily be fitted to many HMVs.

The only disadvantage is: The sensor needs full system voltage to operate and will destruct if you leave your ignition switch on for any great length of time without the engine running. If your older vehicle is a daily-driver, installing one of these kits is a good investment.

MUTT Batts

What would be a good replacement for the batteries in my ’67 MUTT? I just want something that fits right not the expensive military ones. Thanks. — J. Kimber

Group 51R should work.