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After I discovered my coolant leaking a couple of weeks ago, my local dealer diagnosed a faulty water pump, which was replaced, only for the same problem to re-occur at the weekend. They have told me there's a secondary water pump underneath the intercooler which has also failed. Can someone who knows more about what's under the bonnet of an S4 than me confirm that there are indeed 2 separate pumps? What's the purpose of having 2?

Cheers

I would be interested in what you find out, as this morning, I had a low coolant warning light.

I have topped it back up and taken the car for a hard drive and can find no evidence of leaks. Also no condensation on the oil filler cap!

Car runs fine, all tempretures are also fine!

Pete,

There certainly is a secondary water pump, but I'm not sure it's the same as the one your dealer is referring to. It is an electric pump and it is situated in the 'V' of the engine. It's job is to reverse circulate the coolant when it is very hot, in order to dissipate any air bubbles which form as a result.

If the dealer said the pump is under the intercooler then he is either confused or there was a communication problem (or he is just wrong!). The intercoolers (there are two) are located at the front of the car and fairly low down. There really isn't any room below them for anything, and even if there was I can't see the point: It may be tight in the engine bay, but not that tight!

You have:

A main water pump which is driven off the toothed cambelt. This is what is used to pump coolant
when you are driving the car.

A secondary waterpump. This is electrically operated and cools the engine, based on a thermostat,
after you have switched the car off. This is located on top of the engine underneath the near side
engine cover (UK).

AFAIK there are no waterpumps underneath any intercoolers.

As always, cheers fellas. But 2 slightly different explanations of what this secondary pump is for....fisticuffs, or guns at dawn?

Car is booked in tomorrow, so no doubt there'll be a third explanation for the pump's existence from the dealer that I'll post up tomorrow evening