common water pump failures, & their causes
BROKEN WATER PUMP HOUSINGS AND SHAFTS COMMONLY CAUSED
BY:
1) Excessive vibration & unbalance due to:
Bent, cracked, or broken fan.
Fan not squarely mounted on the shaft.
Cracked or bent pulleys due to improper handling or
installation.
2) Belts too tight:
Over-tightened belts cause overloads on the bearing,
greatly reducing its operating life.
They also impose a powerful bending force on the shaft,
causing it to deflect substantially from true center
rotation. The result is large unbalance and early shaft
fracture.
SEEPAGE FROM THE WEEP HOLE:
A few drips from the weep hole is expected until the seals lap in but pronounced seepage is an indication of seal
failure. The life of the seal can be greatly extended by
performing regular maintenance on your cooling system.
Periodic inspection of hoses and coolant recovery tank
will assure coolant levels are correct and that no
atmospheric contaminants that can cause oxidation and sludge
build-up are present. Sludge build-up in the cooling system
is a primary cause of seal failure as well as reduced
cooling system efficiency.
Water Pump Troubleshooting
| Symptom |
Probable Cause |
| Overheating |
Leaks at water pump
bolts |
Leaks at gasket |
Scraping noise when
pump shaft is turned |
| X |
|
|
|
Low coolant level |
| X |
|
|
|
Air pocket in coolant system (1) |
| X |
|
|
|
Faulty fan clutch |
| X |
|
|
|
Inoperative electric coolant fan |
| X |
|
|
|
Restricted exhaust system |
| X |
|
|
|
Retarded spark timing |
| |
X |
|
|
Bolts go through into cooling system (2) |
| |
|
X |
|
Mounting surface is not clean |
| |
|
X |
|
Gasket is misaligned |
| |
|
X |
|
Pump bolts are not properly tightened |
| |
|
|
X |
Rust deposits from mounting surface entering
pump |
| |
|
|
X |
Pump installed without gasket |
| |
|
|
X |
Excessive side play in pump (3) |
(1) Allow engine to cool; restart and run with
radiator cap removed and fill as necessary.
(2) Apply sealant to threads.
(3) Bearings damaged from overtight belt.
Note: A common cause of overheating in cars
equipped with electrically operated radiator fans is a
malfunction in fan control circuits. This may be a blown
fuse, a faulty thermoswitch, etc. After the FlowKooler pump
is installed and the cooling system refilled, run the engine
until the coolant reaches the temperature at which the fan
should switch on. If it does not do so, refer to the
manufacturer's recommendations for troubleshooting the fan
circuit. |
