RonSimner

I have a 2000 A4 2.8 Qattro manual with 128k miles on it. For many years it has been overheating - only going to the first mark past normal. Most of the time it stays right in the middle of the gauge and only overheats when going up hills (or when coming to a stop after operating at normal temperature on the freeway). I finally started addressing the problem by replacing he thermostat, water pump and then the fan clutch. The electrical AC fan comes on with the AC. These repairs have not fixed the problem, so it looks like a coolant blockage or a radiator problem. It does not lose coolant, there is no steam coming out of the exhaust and no water in the oil. Has anyone had this type of problem? Next step is to replace the radiator, but my mechanic suspects a head gasket issue. Thoughts? Thanks, Ron.

ProfileTrader

I have a 1997 2.8 v6 12v and I have the same issue... but only when temps (if I am correct) exceed 100. I live in AZ. Examples of how it operates. When I first start the car form cold (say it is between 100-107) and I drive the freeway at 70+ all is good. If it gets past 110 - even past 115 it may go to just over the 1/2 way mark (not even to the fist hash). However if go uphill a bit It may go up to the first small hash. If I stop and let it sit but not long enough to really cool and dissipate the heat and then get back in the car say 15-25 minutes later and start the car the gauge (upon start up) will be anywhere from the first large hash to the second small hash (just past the first large) beyond the half. After driving for a few minutes it will start to cool down to the 1/2 way mark of it is under 105 or if over 110 even past 115 maybe to between the 1/2 way to first small hash. Just takes a little longer to cool the hotter it is. If I drive around town it operates up to the first small hash past the half way mark even if it is over 115. Oh and one more thing - If I fill the reservoir up to the Max and I drive the car when it is over 110 on the freeway at high speeds and then park it immediately after in the garage - it will spill coolant in the ground from the overflow. I do not notice this if I do the same and park it say when I am going to the store. So I keep the coolant level above minimum but not at or just above Max. If the outside temp is less than that or I am not driving at high speed and stop immediately I have not noticed this issue at all.

The preceding examples are after I did the following. I changed the water pump, thermostat Nov 2018 and the fan clutch in Oct 2016. No change in operation. The radiator started leaking in June 2019. I changed that. I also drained the block in Nov 2018. A lot of dirty coolant came out of it - So I recommend it.

Before I started to work on the car - while living in CA I ad a mechanic doing the work and he apparently did not change the coolant for years only when he did the timing belt and even then he did not do the block. I think that was part of the issue or any remaining issues.

Also the way it operates now (as described above after all the changes) is way better. For example after stopping for 15-25 minutes it would never cool down much. And when I drove around town (stop and go with lights) and the temp was over 110 and especially over I would have to turn off the A/C at stoplight as I watched the gauge get up to the first large hash past the 1/2 way mark and I did not want to risk watching it go further.

I say change the radiator. For my car I bot it from Rock Auto (reputable brand) perfect fit for $87 shipped to me. Also drain the block if yo have not done it.
With all this being said I am satisfied and do not know another thing I can or may be willing to do.

Also I found in the owners manual the normal operating temp can be past past half way mark if the outside temp is high and the car is working hard.
Hope this helps and any questions.. let me know.

I posted pics of the Gauge and Owners Manual page.

clancy

I had a similar overheat issue on hot days or long climbs on a C5 2.7 and the problem was the fan control module. Don’t know if your car has one of these. But mine was not allowing the electric fans to increase in speed. Does your model have a high speed on the electric fan? It may not be kicking up the speed. There is also a switch on the C5 lower radiator hose. Does yours have one of these?