High Temperature Alert

[clogman]

A6 1.8 TQ 2000
Car has been running really well, now coming up on 60K miles (service due very soon) but then this happens...

On the motorway this morning the engine temp alarm went off - temp was reading about 120C.
So I slowed down, came off at the next exit and coasted for a while with the heaters on full, and limped the 2 miles to the office.
Under the bonnet there was no steam, no weird clicking or popping, coolant level was fine.

I took the car out at lunch time and the temperature climbed to the mid-point on the gauge within minutes. I put the air-con on high, fans on full blast, but there was hardly any heat coming through the vents, as the engine didn't appear to be warm yet.

When I stopped and looked under the bonnet again, there were still no weird noises or steam.

Audi tell me I should get the car towed in to their garage where they can start the process of disembowelling my wallet. Any other suggestions before I go there?

One thing to note, which could be a massive red herring:
Over the past few days I have noticed a de-icer type smell in the car, which I think was a spray can in the boot that had been accidentally triggered. But what if it was something else? No internal puddles in the footwells, no other warning lights.

One last thing - anyone know of a decent Audi servicer in north / mid Cheshire? One that doesn't charge hundreds of pounds labour per hour, but still knows their stuff?

[clogman]

update:

coolant level was slightly low after driving home last night, but temperature stayed around 90-95C.

gave it the beans this morning down the motorway this morning and temp went up again to 110C, but cooled as soon as the speed dropped, even on back roads, staying around 90C (its normal mid-point).

If it was the water pump failing, why would the engine cool down so quickly? Why does the engine heat when speed climbs above (ahem) 70 but fall back as I come out of warp?

All I need is something to go on so I don't feel ripped off by the garage when they present me with the bill. Isn't that what all of us really want?

[davegwynn]

Hi Clogman,

As no-one more knowledgeable has popped up in the last day I thought I would at least offer something..

Prior to the Passat I had an elderly, much loved but oh-so-rubbish, Hyundai Accent, which developed very similar problems. Sitting in traffic would see the temp needle climbing too high, and 70+ would see it climb into the red. The fans on the radiator ran ok as the temp increased. Turns out the problem was that the coolant wasn’t being diverted into the radiator as the engine got over operating temperature.
This was before I poked about inside the oily bits meself, so I can’t remember exactly what the bit was, but I do remember the bill was sub £100 from a main ***********.

I guess you could try a couple of things before you take it to the dealers..
Please bear in mind, I’ve not seen the engine bay of an A6 – and forgive me if this is a bit noddy and you have already done this:

Run the car up to operating temperature, then leave it running on the drive. There will be a number of fans on the radiator. On my 1.8 Passat there are a couple, a viscous bearing driven one, and an electric one.
These fans should come on and stop the engine overheating at some point. To the best of my knowledge, the viscous one as the engine gets to operating temperature, and the electric one if more cooling is needed.
If the engine begins to overheat and the fans stay still, then there is an issue with the fans/sensors that turn them on.


Also, the radiator should get really damn hot. If it stays cold, then there is an issue there somewhere (blocked pipes, radiator, the valvey thing that diverts the coolant from around the engine to include the radiator circuit etc).

I'm not sure about what happens when the water pump fails, but I have always imagined that the engine would overheat really really quickly.

Hope this was of some help.. let us know how it goes..

[clogman]

Thanks for the input.

Temp climbed today and I popped the bonnet as soon as I stopped. The driven fan was whirling around, the electric one was off, while the temp was still about 110-115C.

Eventually there was a click and the second fan started, temps fairly quickly fell below 100C.

Radiator and hoses all feel hot. Earliest the local garage can see me is tomorrow, so I'll be limping home again - temp never rises above 90C (the gauge mid-point) if I stay at about 60-65mph.

[davegwynn]

Hmm.. fingers crossed that is it something like a sensor for the secondary fan that is dodgy, and not turning it on early enough/ turning it on erratically.

Good luck with it

[clogman]

Thermostat was on its way out, but the real problem was the water pump - the impeller was ******* (sorry - technical terminiligy, there).
After they fitted it all back together, the car started leaking coolant. There was a crack in the hot water manifold, which only developed after the repair.
Yes, I was suspicious too. But what can you do apart from pay the bill?
Anyway, car is up and running extremely well again, as it got a service while it was in the garage.
Thanks for all the info and advice.