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Operating Temp when Towing

8424 Views 25 Replies 14 Participants Last post by  Rossco
Operating Temperature
I have just purchased a new Touareg V6 180. Have done 4500km now. I recently towed our caravan which is not big 15' to South Australia a one day 800km trip approx. it was a warm day 37c degrees plus. I noticed the temperature gauge that always sat at 90 degrees continually fluctuated between 90 and 105 (still in the normal range but at the high end). I have never experienced this with my other tow vehicles (Land Rover discovery & Nissan Pathfinder). I was towing at 100kph. The car was fantastic and did the job with ease, but I have a question re the temp gauge movement. Is this normal? Have other owners who tow experienced this. The manual does say the vehicles operating temp will be effected by outside ambient temperatures. Advice from the technical people at the VW dealership say this is normal, but as I have said I have not owned a vehicle that has had the temp gauge continually go up and down like this? I would appreciate feedback from others who may have experienced this. As I purchased the Touareg primarily for a tow vehicle and will probably being towing when the ambient temperature will be 35c plus often, I would like some assurance all is ok?
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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.
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After reading through the this thread I decided to add my experience. I own two Tregs (T1 and T2), both have towed several trailers. Neither have experienced the coolant temp gauge moving beyond their "fixed" or "normal" maximum. As others have said, yes the actual temp does change, but these gauges generally don't report it unless something is afoot.

My T2 currently tows an over 6k lbs, 32' in length, travel trailer. We have loaded the Treg to near max GVWR in summer heat above 100 fahrenheit and not had the temp gauge budge. Naturally no reflection of reality, but if mine did move I would suspect something being wrong....because it isn't made to do what yours (OP) is doing. Sounds like you may have a partially sticking thermostat or a bad sensor...or...?
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Thank you for all this feedback. I will approach the dealership now with this new information and see what they say.
I've towed a 1600kg caravan 15000km around Europe in all seasons, up and down mountains etc. Water temp never any different than without the van on. Oil temp does increase when work load is higher with or without the van - Max I think I seen is 120Deg C.
I have an aftermarket (non VW Tow bar) on a 2005 TDI 3.0. I assume I have the standard fan.
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i thought we werent using thanks you's any more ")"(
I note that our 2015 180 TDI is a lot more "sensitive" temperature wise than was our previous 2009 T2. When towing the caravan I will always utilize the manual mode especially when going up any steepish hills. I note that if I leave it in "D" the temperature will increase, but not to the point of being critical and it certainly performs better if I take it out of Auto when under load. This, in my opinion has to be better for the transmission too. It only remains in "D"in ideal conditions when towing our van which weighs in at 2361kg ATM.
I do think back fondly (if that is the right word) to last year when we had to get a whole new engine when the Treg was just 3 months old, because when we towed the van then, it would overheat, due to the cracked engine block and leaking head gasket. What other new vehicle would produce so much joy?
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