invariably comes in at five minutes after 5 on a Friday afternoon, when
every other vendor that might help answer the caller's question is closed
for the weekend. The caller's been on the side of the road for four
hours with a tow truck that has a shredded clutch pump drive belt.
His question: Do I know which belt to get for that tow truck's
clutch pump, and exactly how do you route the belt around all the pulleys?
The clutch pump belt runs off a
pulley on the engine's crankshaft and drives the engine-mounted hydraulic
pump to power the tow truck equipment on smaller tow trucks that don't use
a transmission-mounted PTO (Power-Take-Off). It's a vexing problem
when you lose the belt. With the wonderful clarity that comes with
realizing something too late, the answer occurs to the caller at about the
time I mention it to them: Write down the belt number, and a belt
routing diagram, before the belt breaks.
Here are three reasons to write
down the belt number and diagram:
1. Clutch pump kits do not
use the original factory belt that came from Chevrolet, Ford, Dodge,
etc. The installation of the clutch pump changes the length of the
belt. You cannot walk into the auto parts store, ask for a belt for
a 2005 Ford F-450 with Powerstroke V8, and get the right belt if you use a
2. Clutch pump kits do not
use the original factory belt routing. The installation of the
clutch pump adds at least one pulley to the engine's array of pulleys and
idlers, and sometimes also adds a tensioner that is different from the
original. You cannot depend on the belt diagram sticker that came
with the chassis from the chassis manufacturer to tell you how to route
the belt if you use a clutch pump.
3. Often, when you lose the
clutch pump drive belt you lose the number that's written on the
belt. Sometimes the belt shreds, sometimes the belt falls out of the
Cut out the tag below and write
on it the clutch pump belt number and a sketch of the belt routing.
Make one tag for each truck and photocopy it. Keep one copy in the
glove box of the truck and the other copy in the office. Then buy a
spare belt and keep it in the glove box, too.