TECH TIPS
For RVers, this could be a long, hot summer. But getting out of the heat for many means getting away from the city and to the cool of the countryside. Nothing spoils an RV vacation
faster than a breakdown on the road. One critical breakdown area
can often be fixed before it ever breaks. A little advanced cooling
system maintenance and repair can keep these kinds of breakdowns at bay.
You may not know it, but overtaxed cooling systems can actually cause fires that can burn up your motorhome faster than you
can grab your loved ones and bail out the door. But caring for your
RV’s cooling system isn’t difficult.
Automotive professionals tell us that every power train has its
happiest operating range. Engineers design cooling systems around
those specific needs. But as technology has “advanced,” those
happy operating ranges have grown much narrower—and industry
insiders warn they may get tighter still. Hence, the need for staying
on top of cooling system maintenance. Here are some areas to
check before you head out on the road:
Know Your Hose
All radiator hoses eventually wear out and require replacement.
If a hose goes, it could cause serious problems. With the engine
cool and shut down, feel along the entire surface of all cooling system hoses, including those serving the cab heater core. Hard or
swollen hoses can fail at any time. Cracked or brittle hoses need
replacement, too. Leaks near the terminating end of the hose could
indicate a loose hose clamp—or a bum hose.
Fire department officials say that even a pinhole leak of coolant
onto a hot engine part, like an exhaust manifold, can quickly evaporate cooling system water. The remaining antifreeze mixture can
actually ignite—and make a motorhome go up in a puff of smoke.
Check Your Belts
Drive belts get old, cranky and slippery. Look at them closely—
check both sides by twisting them—to detect cracking, a shiny
“glazed” appearance, or other signs of deterioration. Replace any
suspects. Loose belts do more than drop pants. In your rig they can
cause overheating or other problems. Push down on the belt at a
point midway between pulleys. If the belt depresses more than
one-half to three-quarters of an inch, it could be too loose. Be careful though, an over-tightened alternator belt can damage bearings—a belt tension gauge can give clear direction.
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Us old guys used
to call them radiator
caps, but you may
even find “system
pressure caps” in
places other than on a
radiator. Our coolant
reservoir (overflow
tank) is the only
place on our tow rig’s
engine where you can
put coolant—no radiator cap! A cooling
system kept under pressure is one that boils at a higher point, so
making sure this cap is in good shape is critical. Remove the cap
(ONLY FROM A COLD SYSTEM) and look at the gasket. It should
be solid and supple, with no cracks or nicks that might impair its
function. If you have a cap tester, use it.
You won’t find a “radiator cap” on this truck, just a
“system pressure cap” on the coolant reservoir tank.
Russ and Tiña De Maris
Cool in a Clutch
Keeping the radiator cooled off is that all-critical fan—or even
fans. Loose rivets, bent or cracked blades, all call for attention.
DON’T try to straighten a bent blade, replace the fan. The
hydraulic clutch on a fan “engages” the fan at a given temperature.
With the engine at operating temperature but shut down, spin the
fan with your finger.
If it turns more than
two rotations without
stopping, have it
checked out—it
could be freewheeling when it should be
engaging. Other
clutch problem giveaways? A streak of
dirt or oil across the
clutch. These guys
are filled with silicon
fluid, and when the
fluid leaks out, it
attracts dirt. Another
problem is the clutch bearing—grab the fan at opposing points and
try and rock the fan/clutch assembly back and forth. If it gives
more than a quarter-inch, the clutch bearing is on the way out.
Colored test strips tell whether more SCA is needed
for diesel engine protection.
Russ and Tiña De Maris
The Pump’s a Prime Thing
You don’t want a water pump to give up the ghost while heading down the highway. We speak from experience. But first, don’t
get taken in by unscrupulous replacers of RV water pumps. A tiny
amount of coolant—even a few drops—on the outside of the
water pump doesn’t mean: “Yer gonna lose that pump just around
the next corner.” Nor does the old ploy of “checking the water
pump for play in the bearing.” If the mechanic says he can feel
that the bearing is too loose, ask him to turn your antifreeze into
Jack Daniels. If he can, let him replace the water pump. Water
pumps typically last many thousands of miles. If you see something like a puddle of coolant under your rig and you can’t
attribute it to another source, then yep, your water pump may be
