Over heating ABC V6.......WHY?

[fourringsrus]

Evening all,
Car; late '95 'N' Audi coupe 2.6 v6 ABC front drive manual.
This evening after about 15 minutes run from stone cold on the M20 motorway at speeds of around 65 and maybe about 90 for a few seconds to clear some traffic,I turned onto an A road and after about 2-3 minutes while pulling hard up a steep hill ,I spotted steam coming from under bonnet.
Pulled over to investigate, gauge reading around 110, coolant blasting from expansion tank etc.
Fortunately I had pulled up right outside the Kent showground which had a function of some kind going on ,so nipped in to let her cool down and get some water.
After about 30 minutes I decided she was cool enough to add some water and investigate for leaks, split hoses etc.
Nothing obvious anywhere except that at no time during the episode were the twin electric cooling fans working, which I would have expected to have been roaring while the ignition was on.
Carried on to destination approx 5 miles and gauge still nudging 100-110.
Sat for around 30 minutes at friends , checked reservoir, spot on but still hot and no fans.
Set off home and decided to stick to A roads to keep the engine stress levels to a minimum, a run of about 33 miles and the gauge showed 95-100 most of the way.
Got to a stones throw from where I work and pop , steam again and 110-120 on the gauge and this time the thermometer symbol on the dashboard, luckily I pulled into my yard, allowed 20 minutes cooling ,topped up water etc and still no fans


What drives the fans in respect to fuses, relays, sensors ,senders etc and where are they all located?
I have had the car for 6 months and had no issues before now
The oil is clean, the coolant "was" lovely and clean g12 plus, right up to the point that it went down the drain
The engine is running super smooth, no splutters/hesitance
I'm at the moment of the opinion that the fans are the issue, so please any ideas are greatfully recieved
Gauge has always run at 100 but I take that with a pinch of salt knowing how the gauges mess about on this model
Many thanks gang

Stuart

[adamss24]

Replace the water pump looks like the impeller it's spinning on the shaft...

[95cabrio]

replace the water pump?? try the cheapest and easiest options first.

1) try and rotate the fans with your hands, if they move freely then they are fine
2) wire fans directly to battery and turn on, if they work then fans dont need replacing
3) the operation of the fans is factored on the multi-temperature sensor

http://www.upload.ee/image/1789085/rear.gif

get a voltmeter and check the resistance, if faulty change

when she has warmed up are both in and out pipes of the radiator hot as well and are the pipes pressured? if there is a cold pipe and you can squeeze it with no pressure pushing back then the thermostat could not be opening (a long shot but still plausible) which to remove you would have to take the timing belt off in which case you may as well change all belts, water pump and have a good snoop around your power steering rack as these go bad with age.

if you get to this point then you may as well for the time being keep the fan wired directly to the battery and be gentle with your motor until she has got up to operating temperature and put a fuse in your wiring or a switch so you can turn the fan off in the depths of winter.

[fourringsrus]

adamss24, thanks for the reply but at this stage I feel more inclined towards electrical investigation, many thanks.

95cabrio , thanks also for the reply as you have jogged my memory and highlighted the positions of the various senders etc
While attempting to sort various things out at the time of MOT ,I swapped both the F76 sensor and the G62 from my other 2.6 ABC coupe which was running fine and I actually broke the plastic plug on one or the other but not sure which. I think I now know which one requires attention so will be looking closer in the morning.

Many thankls again boys , I'll report back as soon as possible

Stuart

[scotty33]

I don't think the mfts runs the fans, it runs the gauge and autocheck warning, maybe aircon disable IF overtemp occurs
Fans usually run from 3 pin thermal switch mounted on the rad (not sure same on V6?) . If you jumper the right pairs of pins you should see low and high speed fan functions

Also check the expansion tank cap, it has an internal relief valve, if this is not holding pressure or a seal is out of place, it will boil over at 100 deg

[fourringsrus]

Sorry for delay in reply, computer been gonking about, had no issues all week but when I get time I will be following up all threads of action, many thanks