MAINTENANCEcleaned with hot water and detergent. Whatever
method you use, the jet should be held perpendicular
to the radiator to avoid bending the fins. Some
machines will have what’s known as a sandblast grid.
When the air is pushed through the radiator by the
fan, it’s moving in a turbulent spiral. Any fine abrasives
in the air hit the edges of the radiator tubes and
can cause erosion. The sandblast grid is designed
to take the spiral air flow and make it laminar and
perpendicular to the radiator core so any debris flows
through and does less damage. Sandblast grids are
great in the desert but in, for example, a forestry
application they can trap grass and leaves next to the
core making it impossible to clean without removal.
If you look past the fan and the back of your radiator
looks like a sort of honeycomb, you’ve probably got
a sandblast grid. If you’re not in a particularly dusty
environment and are getting debris build up, you
should consider removing it. Another often overlooked
cause of trouble is the seals around the radiator itself.
The radiator should be sealed into its housing with
little or no air gaps. If these seals are missing, hot air
from the radiator can be recirculated around the edges
instead of being blown away.
The next most common cause of problems is a belt-
driven fan. Even if the belt is adjusted properly, it can
still slip if it’s glazed or if the pulleys are worn. With
the engine off, feel the temperature of the pulley.
If it’s noticeably hotter than the rest of the nearby
components, belt slippage is likely. If the top of the
belt is below the edge of the pulley, either the belt, or
pulley, or both should be replaced.
The next common problem is poor circulation caused
by internal blockage of the radiator, usually brought
on by using water instead of coolant. Whilst water was
OK fifty years ago, it’s a death sentence to modern
cooling systems. The resulting rust blocks radiator
tubes and causes wear to the pump, and cylinder wall
cavitation occurs without the presence of the anti-
corrosion additives found in coolant. Whilst we’re on
the subject of coolant, you may have seen some older
machines with a spin on water filter which is changed
at regular service intervals. These filters contain SCA
(Supplemental Coolant Additive) which was necessary
to maintain the integrity of the earlier types of coolant.
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