DrJohn

I purchased a new 2001 A8L three years ago. It has been, and continues to be, a superb car. This car excites me every time I drive it and I am not at all planning to sell it for many years to come. It has been trouble free until now. The coolant temperature gauge has ALWAYS read precisely at the 11:00 o'clock position for the past three years, even during summer driving. On very hot days, there were occasions that the needle would move to the 12:00 o'clock position but no more. Recently, I had a 20K service performed and the oil (Mobile 1) changed. Since then, the car has run significantly hotter than before. Even on short excursions, the needle now reads at 1:00 o'clock, even when the outside temperature is below freezing. During freeway driving, the needle will move to about the 1:30 o'clock position. I have taken the car to the Audi dealer and they are unable to find anything wrong. Since the coolant warning light has never come on, they state that the car is operating normally and there is no reason for concern. However, the car is running significantly hotter than it ever has and it is difficult to imagine waiting until the engine warning light comes on in order to have the problem fixed. Has anyone else ever experienced this difficulty with their A8 and, if so, what was the problem and how was it corrected? Also, how does your guage typically read while driving during winter and summer? Does it typically move close to the hot indicator, but without triggering the the coolant warning light? Is that normal and to be expected? Thank you for your reply.

'98 Range Rover LWB
'87 Porsche 911 Carrera
'84 VW Rabbit Convertible

bpower1

one blistering NY summer and one winter so far and has always been at "11"

ryoung

on track on hot summer days when the needle gets within a whisker of red. In your case, the higher readings may indicate a sticking thermostat that fails to go sufficiently open.

Just out of curiousity, you might try this test --- When the temp guage is reading above normal, turn the heater on max temp and max fan speed. This is like adding additional radiator capacity (and I do this at the track). If the guage goes back to 11:00 o'clock, it's working, and I'll put my money on a bad thermostat.

One last thought ... Has the coolant ever been topped up with anything other than the Audi spec anti-freeze? Many of the others are not compatible and can gum up the cooling system.

houseofsound

That's pretty crazy that you almost hit the red when you were on the track.

skiwi

the guage is basically useless except in high-temp situations. it is contolled by the motronic and is designed to always display at the 11:00 position in normal driving!

the only way to really tell engine temps is using diagnostic software such as vag-com (group 4, field #3 - values between 85 & 105c). alternatively you could drive it until the condition appears, then go to the dealer who will then be able to determine if the coolant temps are really high, or the gauge is faulty.

if there is an electical fault, or the sender is bad, a code will be displayed (p0116,117,or 118 - also p2181 or p3081). there is another code (p1296) used for a general cooling malfunction.

after this, diagnosis will be a lot easier.

PaulW

If you did a search for bad thermostat here, you would find almost all cases have been 00 and 01 cars. We even did extensive troubleshooting on a couple of them, in every case it was the thermostat.

I believe it's a pretty big job on your car, the timing belt has to come off....but I'm not sure. On the 4 valve motors (97-99) it doesn't.

If you are over 60K miles, consider changing the timing belt and all the other stuff while you are in there.

pw

cwatters

I have a 2000 and had a similar problem last couple of weeks. For about a week guage climbed to about 12:00. Then it started creeping up, but since my typical ride to the train station is less than a couple of miles, I never saw it get much past 1:00. Xmas day went visiting and after awhile the guage was running at the extreme limit of the normal range. Once I hit the side streets it went beyond and eventually the warning buzzer and lights came on. Dealer said it was a leaky water pump and replaced it as well as the thermostat. Aprox. $900 when all was said and done. Since I had heat in the car it doesn't seem to me that the pump failed, but it may have been leaking. I did not see any wet spots though until it actually overheated. May have had something to do with the additional pressure from driving for so long. Hope that helps a little. I sounds like you are heading in the same direction.

ryoung

by the time you go thru the effort to replace the thermostat, since you have access to the water pump, it's the time to replace it also.

cwatters

My thought, if the gasket was weak the extreme heat and pressure??? I know it's running 10:00 now though

skiwi

in the later cars (from my2000), while the literature refers to the "ect sensor" - engine coolant temperature sensor, there is actually no such thing. there are 2 of them, cunningly concealed in the same unit. one, (g2), called the ect, is used by the motronic and is important - the other, g62, also called the ect, is used to feed the temp gauge. it's not important.

display group 4, field #3 shows the output of the g62 sensor which feeds the intsrument gauge.

in the earlier cars, g62 was the one and only. the car in question, has 2 senders...

btw, the bentley mixes them up on the later cars. the wiring diagrams reveal that (the new) g2 is connected to the motronic (replacing the function of the old g62), but the bentley talks about g62 in most of its procedures - a throw-back to the earlier cars. ditto with g2 whcih is described as connecting to the instrument cluster which it doesn't, g62 does....