76 http://www.militaryvehiclesmagazine.com
EARLYORLATE?
I have a chance to buy an M38A1. It has been stored for
many years and seems to be in very good condition. This will be
my fi rst military vehicle, and I want to restore it correctly.
The seller says it is an “early model.” I don’t know much
about these vehicles yet, but I thought most jeeps were the same
except for the style, like MB, M38, etc.
Is there a way to tell if this is really an early model? — Steve
Brown
Most military vehicles that were in production for a fairly
long time had modifi cations or updates. Some of these changes
are subtle and not easily spotted except by experienced eyes...
such as the style of transmission/transfer case skid plates on
WWII jeeps. Other production changes are obvious, such as the
front fender differences between M151s and M151A2s.
In the case of the M38A1, early production models gener-
ally had hinges on the bottom of the grille so the grille could be
folded forward for engine replacement. Many early models also
had the cowl battery box cover secured by thumb-screws.
Later production models did not have a hinged grille and had
metal straps to hold the battery cover in place. There were a few
other differences, such as the seams on the front fenders and
radiator brace rods, but if your potential purchase has a hinged
grill it’s a pretty safe bet it’s an early model.
GEARING UP
Are higher gear sets for M37s really worth the price? — Alan
That depends upon how you use your vehicle. Those gear sets
are well worth the price if most of your driving is on highway.
One used to be able to fi nd third-members in wrecking yards
from Dodge 1-ton civilian trucks that would replace the units in
M37s and allow a comfortable cruising speed of 55 mph. (This
is about what the conversion kits offer.)
You do lose some power. However, I had the aforementioned
units in an M37 and liked them very much.
Since you have higher-speed axles, you can get higher speed
from all the transmission gears. So, even if you have to shift
down on steep hills, you can still go faster.
Off-road performance is not much affected since you have
a low range in the transfer case. Although I don’t know about
the new kits, the old civilian third-members were smaller and
slightly weaker than the M37 original units, which might be
something to consider if you use your truck for heavy hauling or
in severe off-road conditions.
GETTING IN DEEP
I installed a deep-water fording kit on my 1954 M38A1. I
want to try it out. Is there anything special I should know or
precautions to take? — D. Ross
The best precaution would be not to do it. Most smart people
who drive off-road or out in the bush, and who don’t have break-
downs or get stuck, adopt the philosophy of, “do I really need to
go there,” before attempting to climb a mountain or ford a river.
Aside from asking yourself that important question, you
should certainly get a manual that
covers he procedures for deep-wa-
ter fording your jeep. Understand
that driving any vehicle under deep
water is not a casual event. It re-
quires detailed preparation as well
as service after the fact, such as checking the engine, transmis-
sion, transfer case, axles, batteries, fuel tank, and brake master
cylinder for water when you’re back on dry land.
Keep in mind that you talking about fording a 50-year-old
vehicle. Just because you recently installed a fording kit, that’s
no guarantee that the seals, gaskets and O-rings on your vehicle
are in good enough shape to withstand deep water pressure.
If, in spite of my best advice, you want to go ahead with this
adventure, you should have another vehicle standing by capable
of rescuing your jeep if need be. Also, be sure to remove the fan
belt, because water is not compressible. The fan blades may be
bent forward and cut into the radiator from trying to pull water
instead of air.
DROPPING ACID
I paid a shop a lot of money to rebuild the cylinder head
on my 1963 M151. This was completely done in the shop from
removing to installing.
My MUTT is a daily driver, and about a month later it de-
veloped what sounds like a rod knock. The shop guy said that
rebuilding the head raised the compression and put more strain
on the engine’s lower end, so he’s not responsible. What is your
opinion?
The shop may indeed be responsible for your MUTT devel-
oping a rod knock, but maybe not for the reason they stated.
However, it would probably take a CSI team to prove it!
While there is a grain of truth in the explanation that re-
building an engine’s cylinder head (on OHV engines), and thus
raising the engine’s compression, puts more strain on lower-end
components, such as the crankshaft rod and main bearings, this
is mostly an old mechanic’s tale from the 1930s.
What happens more often these days is that mechanics re-
move cylinder heads without completely draining the coolant
from the engine block. The coolant spills into the bottom of the
engine. Even an oil change may not get all antifreeze out of the
oil pan.
When you mix even the smallest amount of glycol antifreeze
and water with motor oil you produce a low grade acid that at-
tacks the engine bearing material.
If a CSI team were to autopsy your MUTT’s engine, the odds
are good they would fi nd dark spots on the rod and main bear-
ings. These spots indicate that acid has softened and eaten away
some of the bearing material.
If this were the case, it would be the reason your MUTT de-
veloped a rod knock shortly after the head was rebuilt. But, it
would probably cost you a lot more time and money to prove it
than to simply take your knocks, chalk it up to experience, and
replace your MUTT’s rod and main bearings — hopefully, not at
the same shop.
My advice is to do this before driving your MUTT any more,
Tech Tips by Steve Turchet