Audi cooling fan

Honest John Back Room » The Back Room Archive
View Threaded
Thu 21 Feb 2002 04:10
Audi cooling fan - pete
The engine air cooling fan is spinning after a cold start up , i haven't touched it so I'm not sure if its free wheeling but it looks to be going at the same speed as the pulley its fitted to.
I understood the fan to be a viscous coupling type which should only engage when hot? so thought it would be stationary when cold.
Is this correct?
Reply | Report as offensive | Link
Thu 21 Feb 2002 08:01
Re: Audi cooling fan - David W
Pete,

If you have a viscous coupling type fan it will rotate a little due to drag in the coupling, even at idle when cold.

Sometimes you can tell by the noise (lack of) that they are only idling. If you can spin the fan on the hub with the engine off it should be OK.

David
Reply | Report as offensive | Link
Thu 21 Feb 2002 19:02
Re: Audi cooling fan - Julian Lindley
David,

What is the principle of a viscous fans operation?

When an engine is cold the fans oil has greater viscosity, which without me having a deeper knowledge of its mechanism, implies oil drag and fan drive. This of course is in conflict with what is required.

In reality, I know that apart from low speed rotation, a correctly functioning viscous drive fan does not operate at low engine temps.

Kind regards,

Julian L
Reply | Report as offensive | Link
Tue 26 Feb 2002 21:49
Re: Audi cooling fan - El Dingo (Martin)
Julian,

The fan hub bearing is filled with a wax that stiffens when it gets hot (phwooarhhh!!!).

(sorry, it just slipped out).

Martin.
Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide

Will you have to pay the low emissions charge?

Use our ULEZ checker to find out if your vehicle is subject to ULEZ charges. Simply enter your number plate into the Honest John ULEZ checker to see if you will have to pay to enter the London Ultra Low Emission Zone.

Check your vehicle