2000 A6 4.2-V8 engine overheating.
What can be the problem? thermostat, water pump, radiator clogged, fan nut running.
Any other?????
Thermostat change; do we need remove timing belt for that??
If remove, we need to change now, I have 74kmile.
What else we need to change with early timing belt change??

 

does it stay cool while you're moving, or does it overheat then also? if not, then it's probably the fan. if it still over heats, either something is plugged, ie radiator or thermostat stuck, or worse you're water pump is shot. go here, scroll down towards the bottom for timing belt kits, they come with everything you need: http://ecstuning.com/stage/edpd/page...ategory=Timing

 

Thanks your advice. problem came up when i drove home with 50 mph on a low traffic road, overheating warning light came up. I stopped, idlering 1 minutes and stopped the engine. Waited 5 minutes, I turned heater on, drove half mile, warning light again, and pumpng out some coolant from the reservoir.
Above timing belt, thermostat and water pump, what else I need to change? Belt tensioner etc? Thx.

 

Get a kit from Blauparts, it has everything you need to change, and even extra (cam/crank seals) =)

You do need to replace timing belt everytime you take it of iw it has been used for longet then 15 minutes, I think

 

it's not a belt tensioner because the water pump is driven by the timing belt, and if a tensioner was bad, you're car wouldn't be running right now. things that this immediately makes me think of would be either a plugged radiator (do you run the recommended G12 fluid?), a stuck thermostat, or a broken water pump. there's always the chance that something could be stuck in a coolant line somewhere, but i doubt that.

 

in either case unfortunately, it sounds as though you might have to be pulling the timing cover off, so you may as well change the timing belt and all that jazz since you're already gona be in there and it is starting to get about that time. 74k miles, if i had to take the timing cover off, i'd definitely be replacing as much as i could while i was in there.

 

It can be a clog in the line some where, or a failed thermostat. If you have to drive it, turn the heat on FULL blast it will help cool the engine a bit.
One way to check is run the car, till it get just a tick past center, then feel the radiator, or use a IR thermometer. If it's cool, then it's not getting coolant, & might be the thermostat, or a clog.

The other thing, is you might have a plastic water pump, & the blade might have failed. You can loosen the bleed screw by the throttle body, & see if coolant flows out of it, do this on a COLD engine. No pressure there, no pump.

If it is the thermostat, then your looking at the TB job, since it's behind the TB.