L-Head Water Pump
When I bought my 1948 Willys
it hadn't been started in six years. The previous owner had mentioned
that it leaked a bit of coolant from the front of engine, but he wasn't
sure exactly what was wrong. Amongst all the extra/spare parts was a
new water pump. That should've been my first clue.
it had been sitting for so
long, I began inspecting the belt and hoses. As soon as I touched the
fan belt, the water pump let go. Antifreeze poured out of the bearing
and shaft. I decided that replacing the water pump would be the first
order of business in an effort to get it running again. Unfortunately,
I didn't take very many pictures - just not enough hands.
procedure should be very similar
for any Jeep or Willys with an L-head 4-134 "Go Devil" engine including
the MB, CJ-2A, CJ-3A, CJ-3B and some CJ-5 and CJ-6 models.
we begin, a couple of warnings:
the cylinder block drain plugs, radiator cap or open the petcock while
the engine is hot or the cooling system is under pressure. You're
likely to burn yourself. Also, antifreeze is poisonous. Children and
animals are attracted to it due to the color and odor. If you suspect a
child has consumed any antifreeze, immediately call 911 or your local
poison control center.
The first step is to drain the
cooling system. Find a suitable container and dispose the used
antifreeze appropriately. DO NOT pour it into the gutter or down a
storm drain. Check with your local water district or garbage company to
determine the appropriate method of recycling used antifreeze.
Disconnect the hose
at the water
pump. The hose was stuck to the pump and since I was replacing it, I
used a razor blade to slice the hose perpendicular to the hose end. If,
when replacing a hose and it becomes stuck, do not force a screwdriver
or other sharp tool under the hose end. Use the razor blade and slice
the hose being careful to make a shallow cut.
Remove the fan belt. I loosened
alternator bolts to release the tension on the belt. After you've
loosened the alternator bolts, move it on its pivot point to free the
belt. I found a skid plate/guard on the leading edge of the oil pan
which prevented me from removing the belt. I loosened the guard's bolts
enough to free the belt.
the fan. Remove the bolts attaching the fan and any spacer
from the pulley.
Remove the pump. The water pump
held on with four bolts. Remove the bolts keeping a catch pan beneath
the engine. When you break the seal between the engine and the water
pump, coolant will likely leak out of the block.
Thoroughly clean the
pump mounting surface of old gasket material.
surprisingly the opposite of the removal.
used Permatex RTV
to make a
gasket on the new water pump before installing it. Basically, I ran a
bead of RTV around each opening on the mounting surface of the pump.
The bolts should be tightened to 17 ft/lbs (23 Nm). I did run into a
slight problem with this step. It's obvious that several people have
worked on the engine over the years. I found 3 of the 4 bolts were
Reattach the fan (and spacer, if
there was one).
Install the fan belt. Route it
correctly over the various pullies. Once you have the belt on, tighten
the bolts on the oil pan guard before you forget about them Tighten the
alternator belts and adjust the fan belt. To adjust the belt, I place a
straight edge across the pullies at the longest straight run of belt.
Pull (or push) on the mid-point of the belt between the two pullies and
measure the distance between the straight edge and the belt. You should
be able to move the belt inward (deflect) between 3/8 and 1/2 inch
(9.5-12.7mm). Once you have the belt adjusted properly, tighten the
Dip the radiator hose end in
antifreeze to make it easier to install the hose. Slide the clamps over
the hose ends before attaching it to the radiator and water pump then
slide the clamps over the connections. Tighten them.
Close any draincocks you've
Fill the radiator with to within 1/2 inch of the fill neck with your
favorite mixture of water and antifreeze. Run the engine until it
reaches normal operating temperature to bleed the system of air. Make
sure that there are no leaks and you're ready to go!