staatsof

I visit this site occasionaly as I almost bought an S4 last year. Can anyone answer this technical question regarding the turbos on this engine. I assume that they are water cooled and I was wondering how the water circulation system works.

1. Is it done with the engine's water pump alone?

2. Is it done with an independant electic water pump?

3. Is it a combination of both?

4. Is there post shutdown water curculation?

5. Is there an independant heat exchanger for the water used to cool the bearings?

Toy_Guy

The turbos are cooled by the main coolant circuit driven by the engine's water pump. There is a loop which splits off for each turbo. There is no auxiliary heat exchanger. Just the radiator.

There is an electric pump in the circuit which will continue the circulation of the water to the turbos when the engine is shut down. This operates only under conditions of high thermal load to protect the coolant from overheating.

staatsof

Thanks for the info.

Do You know how the thermal conditions are measured?

Temperature sensor on turbo bearing housing?

Temperature of water returning from turbos?

Will the pump cycle off/on/off from the cooling of the water and subsequent heat soaking of the bearing caused by the exhaust housing?

Toy_Guy

All I know is from this excellent training guide written by Audi.

Go to the web site then:

Pick Audi S4
Pick Berichte on left side
Pick Audi S4 motor<ul><li><a href="http://audi-speed.com">http://audi-speed.com</a</li></ul>

MingsS4

Cool site, but unfortunately all in German (including the downloads)

Toy_Guy

I guess the site has changed. Sent it to you by e-mail.