Volvo question

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
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The Viscous fan is a fluid clutch, filled with a thick oil or silicone, when the engine is cold the fan will spin because the oil is thick, as it thins the fan stops spinning, the fan is not necessary in fast moving traffic on level roads. However when the engine temperature heats up, the fan has to cut in again, this is done using a bi-Metallic strip. (Remember those from school) The device bends when it gets hot and engages the clutch mechanism. It is done for reasons of fuel economy, if a belt was constantly driving the fan, it would use more engine power that is just not necessary. So the belt only drives the fan hub, leaving the automatic clutch to drive the blades.

Remember the electric fans Kenlowe etc that were fitted to Minis etc, that was done to give the engine more horses to drive the wheels.

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starfighter:
Is that the one that started out as a Volvo 9 and got bored out and fettled by Renault and proved surprisingly good, and was then adopted by Volvo too? Or are there two 11 litre engines?

Correct. It did start life as an engine you would find in a Volvo FM9. Its Renaults own engine software in the ECU, the same as its gearbox. Basicly an Ishift with Renault software. Volvo were so surprised and impressed at how good a job Renault have done with the engine, that they apparently buy the engines back off Renault to put into FM’s.