Thread: TD5 Water temp??

Spot on Bob...

Spot on Bob and Tombie.

Users on several South African forums recommend setting the madman temp alarm either 110°C or 115°C for the TD5 engine. Dave//Blknight.aus and Djam1 both recommend 115°C as a sensible alarm point.

You'll note that is 10-15°C over 100°C and corresponds with the either the point where the electric fan cuts in to aid cooling (110°) or the point when the gauge moves and the engine starts to protect itself by load shedding (115°C). It's also well below the point the coolant will boil IF your cooling system is good health.

Gav is pretty well spot on with his temps. 88-92°C is around the point my engine normally runs - possibly a bit hotter if it's about mid-30's. This seems to be pretty standard for most people. If you are running upper 90's as a matter of course in sub-30 ambient temperatures I'd be having a very close look at the cooling system.

A healthy cooling system has the capacity to run up to 100-115°C under heavy load. You might see that level slogging across deep sand at slow speed in 45°C heat, but it's not normal day to day.

So top priority is a healthy cooling system, and a low level alarm ( I really, really must fit one ).

PhilipA has mentioned the Viscous Fan running full speed at 92°C as evidence that that is the correct operating temperature. The viscous fan running at 92°C is a bit of a red herring. The one of the influences on the operation of the fan is fan speed. According to RAVE's description of the operation:

"As the fan speed increases, centrifugal force and a scoop formed on the fluid chamber side of the valve plate, pushes the silicone fluid through the return port in the valve plate into the reservoir. As the fluid chamber empties, the drag between the drive plate and the body is reduced, causing the drive plate to slip. This reduces the rotational speed of the fan and allows it to 'freewheel'."

At idle the opposite occurs and the fan is driven. The obvious reason for this is that if you are driving there is air moving through the radiator and less assistance is required from the viscous fan - when you are stationary (perhaps with the bonnet up) the fan needs to operate to draw air through the radiator.

cheers
Paul

"As the fan speed increases, centrifugal force and a scoop formed on the
fluid chamber side of the valve plate, pushes the silicone fluid through the
return port in the valve plate into the reservoir. As the fluid chamber empties,
the drag between the drive plate and the body is reduced, causing the drive
plate to slip. This reduces the rotational speed of the fan and allows it to
'freewheel'."

Offtrack this quote only explains part of the operation of the Viscous fan, and I think is describing why the fan makes a noise at start up then becomes quiet.
The bimetallic strip on the front of the fan expands as hot air hits it from the radiator and closes a valve which enables fluid to enter the clutch mechanism and lock it up. This is why it makes a louder noise when the temp in the radiator reaches the target temperature. This happens after the stage above if the temperature of the air hitting the hub reaches the target temperature.
This video shows how it works
[ame=http://www.youtube.com/watch?v=N_GkuTgJr3w]Viscous Fan Drives - YouTube[/ame]

Regards Philip A