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Auto Cooling-System Repair -- Water-Pump Removal From "Weekend Mechanic" episode WKM-102

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Figure A Figure B Figure C Figure D Figure E Figure F Figure G Figure H Figure I

Cooling-System Tip: The cooling system is vital to your vehicle's operation. Failure in the cooling system can lead to damage to several other vital systems within your vehicle, including severe engine damage. It's advisable to have your cooling system checked at 15,000-mile intervals.

Water Pump Removal

The visual inspection and pressure test conducted on the cooling system for the pickup truck revealed leaks in the area of the water pump. In this segment, the water pump and some related components are removed from the vehicle and inspected.

• Hoses are disconnected first in order to access the water pump. Use a drain pan to catch the old coolant. Clean up any spills immediately, as the coolant solution is toxic to humans and pets.

  
  

• Unbolt the fan shroud and fan, and remove the fan and shroud as one piece.

  
  

• In order to remove the water pump from the vehicle, the drive belt (figure A) must be removed first.

  
  

• On this truck (and on many vehicles) the single drive belt operates the water pump and also connects to several other pulleys and components -- crankshaft, power-steering pulley, air-conditioning compressor, alternator, tensioner, etc. It's critical to note exactly how the drive belt is connected before removing it so that the replacement belt can be installed in exactly the same manner and orientation. On some vehicles, a belt diagram is provided on an information sticker underneath the hood. Since our truck did not have such a diagram, Bruce drew one out underneath the hood using a permanent marker (figure B). The diagram indicated the orientation of the pulleys and the route the belt travels around all of them.

  Note: A belt diagram, and removal/installation instructions, should be included in your vehicle's service manual.

  
  

• With the belt installation documented, the old belt can be removed.

  
  

• With the belt removed, the unbolt the old radiator from its mounts and carefully lift it out of the vehicle (figure C). A replacement radiator may cost from $150 to $200.

  
  

• With the belt and radiator removed, work can begin unbolting the water pump from its mount (figure D).

  
  

• Tip: It's vital to keep track of all of the pump's mounting bolts and the location from which each is removed. The mounting bolts are not all one length, and installing them in the wrong locations will cause problems in the reassembly. To keep track of the locations, make a template from a piece of cardboard, and place each bolt in a marked hole corresponding to the actual location from which it was removed (figure E).

  
  

• Continue removing bolts (figure F) until all are removed, and carefully lift out the water pump.

  
  

• Once removed, inspect the water pump (figure G) for any signs of damage or wear. On ours, a leak had developed around the weep hole.

  
  

• Important: A weep hole is a bearing relief hole, and is intentionally placed on water pumps as an early indicator of internal failure. Once a weep hole begins leaking, the damage inside is already done. Don't ignore a leak, and don't attempt to "repair" or plug a weep hole. Simply replace the whole water pump. A replacement pump should cost somewhere around $30.

  
  

• When the water pump is installed, its rear is mounted to the front of the engine, and the fan clutch is attached to its front (figure H). The fan, in turn, faces the radiator and, when engaged, helps to draw air through the radiator. A single drive-belt drives the fan and water pump. Commonly, when a water pump fails, the fan-clutch (figure I) fails also. In fact it was determined that a wobble in the fan clutch, due to wear or poor fit, had caused the water pump to wear out prematurely. Our repair will include replacing both the water pump and fan clutch. Replacing one without the other might result in a similar repair in the near future. A new fan-clutch costs around $30.

In the segment that follows, the thermostat and temperature sensor are checked.

RESOURCES :

The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books

How Cars Work
Author: Tom Newton
ISBN: 0966862309
Publisher: Black Apple Press

Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896