Pajero Owners Club of South Africa

Hi I have a 2003 3.2 DiD with 197000 miles on it love the car but under hard acceleration there's a loud roaring sound from engine or gearbox is this normal or do I have a problem, could it be the viscous fan it has a full service history with 21 stamps in the book, any help would be grateful Andy.

HI Madtrucker.

Is this 'roaring' rev based or speed based. ie. Does it increase/decrease with road speed or engine revolutions?

Generally a viscous fan coupling will fail in a way that makes the fan turn slower (because of loss of viscous fluid) = quieter, rather than failing in a way that causes it to lock up = run faster / noisier.

The viscous fan operates on its own built-in thermostat, which works progressively I think. If the temperature of the air coming across the radiator onto the fan is such that the fan largely locks up (there will always be some slip), then there will be more noise than when the temperature is lower and the fan is largely spinning freely.

You can hear this difference in noise when you start up the engine when cold and rev at about a steady 2600rpm or so. Initially the fan is locked up and so it is noisy because the fluid in the coupling is not distributed . As the fan warms up a bit (maybe 3 or 4 minutes) you will hear the "engine" become quieter as the fan slips more (as it should).

Once the air temperature from the back of the radiator increases significantly the "engine" noise will start to increase as the fan coupling slips less.

Hope this helps some?