Things to check around the water pump (U20):
Water Leaks: Most common problem. There is a "packing" or seal
in the back of the pump. If you use a flash light, mirror,
and a CLEAN ENGINE you'll see the weep hole on the pump.
Water should not be leaking out of the weep holes, unless
the seal goes bad. Replace the pump.
Pump Bearings. Usually I slipp off the fan belt, and wiggle the
fan. With my "tuned fingers" I can feel a sloppy bearing,
but it is rare for the bearings to fail if the belt was
always properly tightened. (about 1/2" freeplay when pressed
with my thumb. Engine OFF obiously). Pump is noisy. Replace it.
Pump backing plate: The back of the pump is nothing more than
a steel plate. Years of running plain water, rust, corrosion,
etc. can eat a hole into the steel plate causing a leak. You'll
need a new plate, and if the maintance was that bad... replace
the water pump.
Large 10mm stud. This stud on the water pump screws directly into
the engine's water jacket. You need pipe sealant on the end
of the stud. I have seen a few studs eaten away from corrosion,
resulting in a water leak near the water pump. I always use TWO
nuts, and remove that stud and inspect it during a water pump
replacement.
OEM Water Pumps - Abouut $150 (??) from Nissan. Highly recommended
to just bite the bullet and replace it. They will not fail immediately,
but usually leak for ages. Keep your engine clean, look for signs of
the water leakage and check the radiator daily. Overheated and warped
U20 heads are expensive to repair, or replace. If you replace the
water pump, KEEP THE OLD ONE. Read below.
Rebuilt Water Pumps - Only thing really in a water pump is the bearings
and seals. An excellend quality rebuilt is better than new, in some
cases (improve seal). Dan Garrison (who is on the list) had some rebuilt
for a reasonable price, and sold them at Mt. Shasta.
Other ITEM: Fan Clutch. The OEM 2000's in 68-70 had little wax pellet
type fan clutches that FAILED. Replacement item is a solid aluminum
part. I would change the 7 blade fan to a 4 blade item and use the
aluminum spacer.
Common leak point: Intake Manifold Gasket. Water passages are built
into the bottom of the intake manifold. Common to discover a small leak
from there. Look for signs of water stains.
Removing the water pump. Years of aluminum housing to a steel stud
means it will be stuck tight. I use a RUBBER MALLET and pound like
crazy. It is hard to double nut the stud, with the pump in place...
but just twisting it will help break the aluminum/steel bond holding
it on. When I replace the pump, I wipe a little antisieze along the
studs to prevent future corrosion.
Cheers,
Tom Walter
Austin, TX
|