Military Vehicle Tech Tips December 2019

Seek The Source

A weak or cracked valve return spring may cause an annoying tapping or clicking sound, especially on L-head type engines — even if the valve lash is correct. To easily locate the defective spring (or springs), remove the valve cover. With the engine warm and idling, insert a flat-blade screwdriver into each spring, one at a time. The tapping sound will stop when you’ve found the weak or cracked spring.

FLOATING HMMWVs?

Can the Army HMMWV float in water?

No. Neither can Navy, Marine Corps, or Air Force HMMWVs, though experimental amphibious models may have been built, or at least considered.

Don’t feel bad. It’s a common notion that HMMWVs are amphibious, or at least can float. HMMWVs are actually designed to take on water when fording, and drivers are trained to let the vehicle fill up before entering deep water. If a vehicle floated it wouldn’t be able to drive through a river or stream.

Like most U.S. M-series military vehicles, there are deep-water fording kits for HMMWVs but — as of now — there are no truly amphibious variants.

M35A2 UPGRADE

I own a 1970 M35A2. Would it be possible to upgrade my truck to the big single tires and air inflation system of the M35A3 trucks? The axles look about the same as my M35A2. — Mark Bollinger

Just about anything is possible when it comes to vehicle modifications — as long as you have the skills, tools, and money to make them.

The same axles were, indeed, used on the M35A3 rebuilds. They were adapted for the newer wheels and CTIS (Central Tire Inflation System), however. It might be wiser — and definitely a lot easier — to buy or trade up to an M35A3 rather than go through all the expense, time, and trouble to upgrade your present truck.

GAUGING A G-506

I bought a WWII Chevrolet one-and-a-half-ton cargo truck. I’m not sure what year it was made because the data plate is missing. The truck is registered as a 1946. This truck has an instrument panel that is the same as civilian 1940s Chevy and GMC trucks, so I guess it is an early model. Can I install military gauges in this truck? — Trevor Anderson

Your G-506 is indeed probably an early production model, which used the civilian style instrument cluster. It’s too bad about the missing data plate.

It used to be common practice in many states to register military vehicles by the year they were released from the government rather than by the actual date of manufacture. This was especially common after WWII, and is probably why your truck is registered as a 1946.

If you’re good at wiring, you can replace the civilian style instrument cluster with one from either a later model G-506 or from a closed-cab GMC CCKW. However, your truck would be more historically valuable if you kept it original.

You might consider doing some research to find an accurate date of manufacture. The data plates were usually mounted on the glove box doors of 1940-41 trucks, then above the windshield on later models. You should be able to obtain repro data plates from some of our advertisers, as well as manuals.

HOLY HOOD, BATMAN!

I’m buying an M38 Jeep. What is the purpose of the irregular shaped hole in the right side of the hood?

That opening served two purposes. It was for routing the air intake hose when an M38 was equipped with a deep-water fording kit, and also for mounting the electrical connector when the vehicle was fitted with a “jump start” kit. When not equipped with these kits, the opening was covered by a plate.

You should be able to locate either the appropriate kits and/or cover plate from some of our advertisers.

WHAT’S IN A NAME?

I am new to the historic military vehicle hobby even though I have been reading a friend’s Military Vehicles Magazines for years. It was the magazine and your user-friendly articles and tips that finally convinced me to buy a 1944 Willys MB. Now I’m sorry I waited so long because the Jeep is really fun to drive and work on. My eight-year-old son thinks so too.

We will probably be bugging you with questions in the future but for now I’m curious why the government stopped putting names like Dodge, Willys, Ford, Chevrolet, GMC, etc. on vehicles later during WWII? Some people say this was in case the vehicles were captured by the enemy but this doesn’t make any sense to me. What would it matter if the enemy knew what company made a vehicle? — Danny DiMarco

Welcome to the military vehicle hobby — both you and your son — and thank you for your kind words about the magazine and my writing. Feel free to ask all the questions you want.

As to this question, the government didn’t put company names on vehicles, the manufacturers did. Since the military had its own designations for all its vehicles in regard to what they were, as well as for parts, repair and maintenance, there was no reason a soldier, sailor or airman needed to know he was driving or working on a Ford, Chevy, Willys, Dodge, or GMC. The enemy already knew what companies made the vehicles; and the names were just free advertising. The government finally ordered it stopped later in the war.

Many vehicles of our enemies at the time also had manufacturer’s names or logos on them, such as the Opel Blitz trucks used by the German Armed Forces.