Help please. Temp gauge spikes but does not "redline". Highway driving does not cool it off. Fan clutch is weak, but that should not make any difference on the highway. I am thinking thermostat (which is easy on any other car that I have owned), but other posts indicate this is a big job (timing belt, tensioners, etc.). Is this true? Any pics or step-by-steps?
A weak fan clutch could definatly cause this problem. As it sits in traffic, the fan cant spin fast enough and has no air flow to help cool it off and thats why on the highway it runs at normal temperature. I had my secondary cooling fan burn up on my A6 and was causing mine to run a little hot. I would definatly get the fan replaced.
Sorry for the "necro" post, but I'm having a similar issue and wanted to see what you guys thought.
Same car, ~35k miles. Had temp sensor replaced 2weeks ago because car would warm up and gauge would go to "normal", then back down to zero after a few more minutes. After picking up car from shop, gauge worked fine, but over the last week, gauge has been creeping higher, whether highway or sitting in traffic. Now rises past normal to above the "2/3" tick mark. Checked fans and coolant level, all looks good.
Could the temp sensor change have caused problem, or just illuminated it? In which case am I now facing the dreaded "thermostat replacement"?
Posts: 5081
Joined: 2/24/2007 From: Sacramento, CA Status: offline
Both of you guys need to actually find out if the engine is actually overheating by either checking the temp of the coolant hoses with a temp gun or your hand. If the temp gauge reads hot and the coolant is indeed warmer than normal then the answer for both of you would be the thermostat, no doubt in my mind. While your in there of course do the T-belt, rollers ect.
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2001 A6 Quatro 4.2 overheating - 
