forum.audiv8.com Foren English Audi V8 Forum Overheating ABH

It's started overheating in slow traffic, around town, stop start motoring.
The electric cooling fan is not starting on any speed, but does run if powered up by another source. I'm thinking of running a switched line as a stop gap.
Once moving at a decent pace, 50mph/80kph, it returns to a normal running temperature fairly quickly.

From a normal start, the car is warming up sensibly. Heater system appears to pass warm air as expected during warm up.

UK car. Was running fine, no gradual getting worse symptoms. It just got hot one day, on a journey I had done a hundred times.
Any suggestion regarding specific items, before I allocate a bunch of time to work out where all the circuits run?
Should it be possible to run the fan via the diagnostics cable?

In Antwort auf:

---

Should it be possible to run the fan via the diagnostics cable?

---

No.

You can try to unplug the connectors on the temperatursensors, watch attachment, german but I think you understand what it means

Also check the viscous clutch of the cooling fan, driven by the belt. At hot engine it needs to stop reving nearly simultaneously withe the engine, when you shut it down. And at hot conditions the clutch needs to feel tight (but not completely solid), when you spin it by your hands. At cold engine id needs to be rotatable with just one finger.

I guess the clutch is, for want of a better word, Kaput.

Hot; engine off, by a flick of the fingers, it rotates by maybe 2/3 fan blades. But, it also spins freely sometimes.
Cold; it rotates 2/3 fan blades, but never freely.
Engine running, it appears to be constantly spinning.

Now, I need to understand why the electric cooling fan is not doing it's job.

I'm hoping to swap the engine, but there is little point in putting a good engine in with faults.

Yes the clutch is worn (kaputt )
You need to replace it. Mind the left hand thread of the central nut.
The malfunction of the aux fan is another bug, but not depending on the viscous clutch.

i'm beginning to suspect the upper temp sensor, but my thinking may be flawed.
once i have the rad sensor exposed, i can hopefully prove the temp sense circuits.

Cooling fan replaced; or rather the clutch. The fan by default, as I had a spare in the stock pile. Result. Temperature under control, for now. But it's an old clutch, too. So I'll order a new one.

Now, it's having an issue revving above 1600rpm. Generally fine, pulling away gently. Once moving, if I accelerate hard, it has a minor hiccup at about 1600rpm.
If moving slowly, and accelerating gently, it is quite obviously being limited at 1600rpm.
If I rev the engine when stationary, gearbox in N or P, then it also has a very obvious restriction.

Any ECU faults stored? Could be a sensor issue...

I think a separate thread is called for. What this (next) space.