[Black Grouse]

Most modern cars have electronically smoothed temperature gauges so it may well show 90C normal all the way from 60C to 120C !!! My previous Hyundai was like that and my Touareg certainly shows 90C normal on the gauge when the ECU/OBD temperature is still 60C but rising.

I use a Scangauge II plugged in the OBD port to show what the ECU is seeing - I know that my Hyundai gauge only moved off normal at 120C as the head-gasket blew.

My Touareg hasn't gone beyond 100C at the OBD in towing use - but I'm in a UK in winter!

 

[Black Grouse]

I had the our best local dealer ask VW tech support why. They said "customers were complaining the temperature gauge moved around to much". In other words "Dumb it down for the stupid people!" :-/

Some manufacturers have removed it altogether and replaced it with a warning light that tells you your engine has just boiled over - a bit like the low oil pressure warning light that tells you your engine has just gone bang!

 

[Black Grouse]

I am referring to the water/coolant temp. When towing after about 1 hour of driving the temp guage rose to about 105, then dropped, it then continued to do this constantly throughout the trip never really going beyond 105 approx. when I slowed to 60kph when going through a town it fell quickly to 90, and soon after when accelerating to 100 kph it soon repeated the fluctuation between 90 - 105. The VW technical advice was that this was normal and that the thermostat was opening and closing as expected and the fans were cutting in. The reason I raise the question is that our current van is a light pop top and we are considering a larger full size 17' van that wil be heavier all round (tow ball and ATM) for our loop of Australia, when it is highly likely the outside temp like on this rip could be quite warm. Thanks for all the feedback to date.

It is of course normal for any (modern) engine coolant to exceed 100C, that's why pressurised systems are used.

From previous diesel towing with a Hyundai, the coolant temperature constantly fluctuates, uphill towing increases the heat to be dissipated from the engine and transmission while light throotle downhill generates very little heat.

Currently, the UK versions of Touareg get a cooling fan upgrade to 850w IF the factory-fit towbar is ordered, although at least one owner has toured Spain this summer with a 2300kg caravan, but using an after-market towbar and only the standard 600w cooling fan - but the fan upgrade might well be standard on Australia-spec Touaregs anyway.