Virtual Mechanic

PURPOSE
Water is designed to maintain normal operating temperature.  Water will only perform this function if all other components are operating correctly.  Water should include an additive to prevent corrosion and erosion.  If your vehicle is driven in either a very cold or very hot climate it may be necessary to add either an anti freeze or anti boil solution.  This will only work effectively if the corrosive inhibitor is changed every 12 months.

THINGS TO LOOK FOR
The colour of the water tells a very good story about the condition of the cooling system.  Brown water is the worst, clear water is not good; green water is best and it needs to be changed every 12 months to keep the colour at its best.

IS IT EXPENSIVE TO REPAIR?
If your vehicle is pre 1990 then a good corrosive inhibitor, eg Castrol, may be okay.  If it is after 1990 then contact your dealer as the seals and welsh plugs require specific inhibitors to protect these components.  These additives may be expensive.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT
If your vehicle has brown water, disconnect the heater hose and remove the radiator cap and secure a garden hose in the heater hose and turn on a moderate pressure.  This is the best way to reverse flush the cooling system.  Please note: this should only be done when the engine is cold.  It may require several applications until the water runs clear.  It is a good idea to turn the heater tap as this will also flush the heater core, in case it might be partially blocked.

PURPOSE
The viscose fan is attached to the water pump and designed to cut in and out depending on the temperature of the water.  The fan will last at least 5 years or 100,000Kms.  After this the fan should be checked periodically every 10,000Kms for its effectiveness.  The viscose fan is a fluid substance that changes its viscosity depending on the heat, allowing the fan to freely move or lock up on a one to one ratio with the pulley.

THINGS TO LOOK FOR
A viscose fan should cut in and out, if monitored over 1/2 hr of the engine idling.  Use extreme caution with the viscose fan or any fan blade when checking.  The best way to check the fan is to idle the engine for about 1500 revs per minute to 2000 and you will notice when revving the engine while hot, more of a fan noise will be apparent.  Then when the cooling system cools down the viscose fan is not consuming any energy from the fan belt or water pump pulley.  A viscose fan may also cause the engine to overheat at moderate to high speed.

IS IT EXPENSIVE TO REPAIR?
Viscose fans may be expensive to repair depending on the make and model.  It’s always a good idea to replace a viscose fan with the original type.  They could cost around $150.00.  Getting one from the wreckers is not recommended as most of these fans are faulty.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT
If you are stranded and the fan is locking up, cooling the radiator, then you can try overhauling the viscose fan and putting a bolt in to prevent it from free wheeling just to get you around.  But it does affect your fuel economy.

THE EFFECT
This type of problem will give the same affect as a blown head gasket.  It will cause the cooling system to appear unstable.  It may also cause the upper radiator hose to tear apart as the thermostat decides to open with a great force of hot water.

THINGS TO LOOK FOR
If you decide to put another radiator hose on.  What you  need to do is feel the upper and lower radiator hoses at normal operating temperature, very carefully, just in case the radiator explodes, and they should be almost the same temperature.  If one is cold and one is hot, this is an indication of a sticking thermostat.

COST
To replace the thermostat it will cost $30.00-$90.00 depending on the make and model of the vehicle and also depending on how old the vehicle is.  The thermostat housing bolts may break as you try to remove them.

PURPOSE

The thermo fan switch when it reaches its designed temperature is designed to switch on and when it reaches a lower temperature, it is designed to switch the power off.  The thermo fan switch receives power from the fuse box.  When it reaches a temperature the switch will bridge the terminals thus turning the thermo fan on.

THINGS TO LOOK FOR

Check that the connections are secure and observe that the thermo fan is switching on and off.  Sometimes this may not occur and just manipulating or wiggling the terminals may cause the fan to switch on.  If this is the case then take the terminal off and clean it and refit it.  Otherwise replacing the switch might be another option.

IS IT EXPENSIVE TO REPAIR?

A thermo fan switch is a costly item at around $60.00-$90.00.  It’s better to buy the same type of switch as the original.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT

If stranded the switch may be bypassed and the terminals bridged, but remember this will put a load on the battery and will always turn the fans on when the ignition is turned on.  Or on some vehicles, if you bridge the terminals it may stay on indefinitely.

PURPOSE
The thermo relay is a heavy duty switch to prevent the request switch from overloading with excessive current or heat. 

THINGS TO LOOK FOR
As the thermo fan operates over years the internal mechanisms may start to wear and cause a resistance in the thermo fan relay causing an overload on to the relay and the fuse.  A common sign is a faulty relay.  Melted terminals on the relay indicate that the thermo fan may be overloading the system or drawing too much current caused by an internal fan problem.

IS IT EXPENSIVE TO REPAIR?
If it is a standard thermo relay it may cost around $20.00.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT
If all other relays are the same specs, ie they may have 30 or 60 amps, make sure that the thermo fan relay is the same as the other and then just swapping the relay with another just to get you home if you’re stranded.

THE EFFECT
The cooling system will maintain normal operating temperature under all driveable conditions. 

THINGS TO LOOK FOR
It’s always a good idea to look at the thermostatic fan to understand how it operates.  Because thermostatic fans are thermostatically controlled and they should switch on and off.  A good thermostatic fan in a very good cooling system will switch on for somewhere between 20-40 seconds.  If the fan switches on for longer than 60 seconds this might be a cooling system that is unable to cool down with the thermostatic fan.  Another problem might be associated with the cooling system.  If the fan stays on for 5 seconds, this is an excellent cooling system as it never requires a lot of effort from the thermo fan.

PURPOSE
The thermo fan fuse prevents the wiring or the motor from melting from a short circuit.

THINGS TO LOOK FOR
Fuses don’t just blow for no reason at all, they blow when they are overloaded.  If a fuse is blowing as soon as you put it in, you need to have an auto electrician check it out.  It shows that there is a definite short in the system causing the fuse to blow.

IS IT EXPENSIVE TO REPAIR?
Replacing a ceramic or glass fuse is inexpensive.  A good idea is to carry a few spare fuses in your vehicle.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT
It is usually a 15-20 amp fuse.  If you try a 25 amp fuse and it blows go no further but remember if you have air conditioning turn it on as it may switch on an additional fan and drive at least 60Kms.  This will also keep the engine cool.

PURPOSE
The temperature sender unit is a vital component designed to measure the water.  As the water temperature varies so does the value of the resistance inside the temperature sender thus sending a different reading to the light or gauge.

THINGS TO LOOK FOR
The temperature sender, whether it be connected to a light or gauge, must have a secure terminal attached to it fitted with a temperature warning light.  The light should appear when the ignition is turned on.  If fitted with a gauge the gauge should start on cold when the ignition is turned on and gradually move to another value to around normal position.  Again, temperature gauges and lights must be listened to and rectified if they continue to come on or climb up the needle.  If the needle climbs up high it’s time to turn the vehicle off.

IS IT EXPENSIVE TO REPAIR?
A temperature sender unit sending the value to a gauge may be costly to replace.  The temperature sender gauge type may cost $30.00-$80.00 and a temperature sender sending the value to a light may cost around $20.00-$30.00.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT
It is not a good idea to disconnect a temperature sender as it will save a lot of time and money when this warning device is required to turn on or give you the correct value of the water temperature.  If in doubt, see your local auto electrician.

PURPOSE
The temperature gauge is designed to let you know what is happening in the cooling system.  To let you know in advance if something is wrong.  The gauge should always start on the cold when the engine is first started, then climb to a normal operating temperature after running for about 30 minutes.

THINGS TO LOOK FOR
Gauges must be seen at all times.  They must move from one value, being cold, to another value, being hot.  If the gauge stays on cold or doesn’t move then this is a warning sign.  Get it checked ASAP.  The same applies if the gauge stays on hot or just in the middle.  If a gauge climbs 3/4 of the way the engine should be switched off and then wait for at least 30 minutes before checking the water.  Every minute of driving a vehicle on high may add a $100.00 to the repair of the cooling system.

IS IT EXPENSIVE TO REPAIR?
Temperature gauges can be expensive.  The wreckers is an option.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT
No temporary repair for the temperature gauge.

PURPOSE
The starter motor relay is designed to switch a 12 volt power supply from the ignition to the starter motor solenoid.  The starter motor relay may also be fitted to an older vehicle with a possible voltage loss on this 12 volt supply.  A starter motor relay is a high current switch that may malfunction after 5-10 years in operation.

THINGS TO LOOK FOR
A starter motor relay if fitted as an after market item may malfunction if the wiring connected to it is not soldered correctly or the relay itself is not of good quality.  Relays are only as good as the power connected to them, the connections and the relay itself must be of good quality.  A clicking starter motor may be the cause of a faulty relay.  Bridging the starter motor may determine this as being a faulty relay, faulty wiring or an intermittent problem with the inhibitor switch.

IS IT EXPENSIVE TO REPAIR?
A standard relay will cost around $25.00.  Consult with your local auto electrician about fitting a relay as he might have the relays made up with the wiring, ready to install onto the starter motor.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT
If you are stranded on the road and the relay decides to malfunction, bypassing the relay or bridging the starter motor might be the only way to start the engine enabling you to get home.