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R Dawson (
Posted on Monday, 06 May, 2002 - 08:13:   Edit PostDelete PostView Post/Check IP

Does anyone know how much resistance there should be in the drive for the radiator cooling fan on my '68 Shadow? The engine seems to run slightly hot but not boiling, what kind of drive is it? fluid?
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David Gore (
Posted on Tuesday, 07 May, 2002 - 01:01:   Edit PostDelete PostView Post/Check IP

There are two different types of cooling fan for early shadows - the original unit was a direct drive from the fan belt pulley and later cars were fitted with a viscous drive clutch between the pulley and fan. The direct drive units had a "spider" connecting the fan to the drive shaft whereas the viscous clutch type has a drum between the pulley and fan.

If the fan is turning at the same speed as the belt pulley {mark fan and pulley with chalk and check with timing light}regardless of whether the engine is cold or hot, overheating is most likely due to one or more of the problems detailed below. If the fan runs slower than the drive pulley regardless of whether the engine is cold or hot, the viscous coupling may require replacement. If the fan runs slow when the engine is cold but its speed increases as the engine/radiator/air flow gets hotter than it may be assumed the viscous clutch is operating correctly and the overheating may be due to a worn pump, clogged water passages in the engine/radiator, a defective thermostat, slipping fan belts, weak fuel/air mixture, incorrect timing or any combination of these.

In all cases, it is assumed the water temperature has been checked by a thermometer and not the temperature gauge indication. Also check if the problem is speed related - does increasing road speed on a flat road reduce the engine temperature as air flow through the radiator increases?

Hope this helps to identify if you have a problem or not - if you need more information please advise what your checks have revealed and I will try to give you more specific information.

David Gore - NSW Shadow Self-Help Group
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bob (
Posted on Monday, 22 July, 2002 - 02:09:   Edit PostDelete PostView Post/Check IP

On Ford cars with viscious couplings I used stop the engine hold a hammer handle against the fan get an assistant who is ALERT to start the engine pick the revs up and the fan should try to turn more against the hammer when the revs get to 1500 rpm let the fan go and it should pick up speed fast with a big whoosh of air which you can hear and feel, but this was on 2.0 Cortinas not expensive RRs
Also worth a try if the car only gets hot in traffic but once on the move the air flow cools the engine down -- fit an electric fan as an additional.
Also a tip with all water cooled cars that have water heater valves. If the heater is pumping hot air it means that the system has water in it, but it could still be low though. If the heat is on the cooling capacity of the system is increased.
One last thing
Do check that the radiator gills where the air goes through are not clogged with dead bugs etc. Check Air con as well.
And also Do take Daves advice about the themometer