Water pumps move hundreds of
gallons of coolant. Eventually, the bearings (Fig. 7,
A) and seal (Fig. 7, B) wear out, causing
a noise or leak.
Some leakage around the water
pump weep hole is evidence of normal coolant weepage, which prevents coolant
from accumulating around the bearing seal. This is a normal condition. However,
if there is a constant drip or stream out of the weep hole, especially under
pressure, the seal may be worn and the water pump needs replacement.
Water pumps also may fail due
to contamination and corrosion caused by the lack of proper maintenance or
servicing of the cooling system. Failure to flush the cooling system when the
water pump or other system components are replaced can leave excessive
contamination and lead to repeat failure. (Fig. 8)
Also, if there is a visible
wobble in the shaft or the bearings are making noise, the water pump needs to
be replaced.
Service Tips
When replacing a water pump,
there are several key items to keep in mind in order to complete a successful
repair and eliminate a comeback. These include:
- Determine the root cause of
failure, especially if the water pump failed prematurely
- Flush the cooling system
completely
- Use the recommended 50/50
coolant/water mix
- Do not use any non-approved
flush agents
- Follow the instructions
that are included with the water pump
- Use sealant tabs if
recommended
Engine Coolant
Quality coolant and water are
critical to water pump operation. Contaminated coolant, depleted coolant, and
poor water quality can result in corrosion and seal damage.
Water quality varies greatly
in different areas. Tap water contains chlorine and chloride, which are
corrosive to aluminum. Unclean water also leaves mineral deposits in the
cooling system, which can reduce coolant flow.
Engine coolants come in
various colors and formulations, ranging from conventional green coolants to a
variety of long-life coolants that may be orange, red, gold or blue. The color
is mainly a dye, but the chemistry of the coolants is different.
Vehicle manufacturers have
different coolant requirements and there may be some confusion over which type
of coolant to use in a vehicle. Check the Service Information for the correct coolant
for the vehicle being serviced. Most manufacturers do not recommend mixing
long-life coolant and conventional coolant. New coolant may be degraded if the
correct 50/50 coolant/water mix is not used or if there are excessive
contaminants in the system.
When replacing a water pump,
it's critical to flush the cooling system. Prior to performing the flush
procedure, remove, clean and reinstall the coolant recovery reservoir. To flush
the system, use power flush equipment or thermal cycle the system with clean
water three times.
Installation
After installing the new
water pump, perform the following to ensure a proper repair:
- Torque the bolts to the
manufacturer's specifications
- Adjust belts to the proper
tension (if applicable)
- With the new pump installed,
turn the hub by hand and check for rotation
- Pressure test the system
for leaks
Leave a comment