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Discussion Starter · #1 ·
I was on the way to Castle Combe this morning going over the severn bridge when a big STOP sign appeared on the dash with the sign check coolant. So I pulled over, turned the car off, had a quick check and turned the car back on. The car had little power even when dropping into a lower gear and the temperature shot to 130C so I pulled over and called the AA as I didn't want to risk driving it any further till I knew what was wrong.

The AA man came and the coolant level was fine, the fans worked fine and when idling and revving the engine at a stand still the temperature did not increase. He thought it may have just been a little problem that had sorted itself so he said he would follow me to junction 18 of the M4 and if the temperature increased to pull over. I got about 100 metres and the temperature shot straight back up again. So i ended up getting a tow back to my house. He reckons it could be the themorstat. Anyone got any ideas?

Not the best of starts to the day at all
 

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Mine did that; cooling fans were dead. Maybe yours are intermittent? I
waited 2 hours for the AA man and when he saw it he said there was
nothing he could do as it was a MKIV, dealer job. Replaced under warranty though
 

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Discussion Starter · #4 ·
Is there a way to test if the fans are dodgy? They seemed to come on fine though. It's looking like a dealer job [:(]

I just went and checked the fans using the advice from Andymacs thread about turning the AC on and the fans worked as they should. If it was the water pump would there be leaks? Because there are no leaks anywhere and the car has only done 20K
 

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It could be the water pump. The impellor is plastic and breaks, so i guess if this has happened there would be no leaks but the engine would overheat quickly. Thermostat might be a good place to start tho' as the water pump is an expensive job due to work involved.
 

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Discussion Starter · #6 ·
I'm hoping it's not going to be the water pump as thats going to be very expensive.  It's booked in with VW for first thing on Monday morning.  I'm not looking forward to it at the moment.  We shall see.
 

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Fingers crossed for you mate. IF it is the water pump, look into/think about having a cam belt change at same time as i think the cam belt has to be removed to do the water pump. Hence the expense. All depends on age of car/how long you plan to keep it.
 

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Discussion Starter · #8 ·
Having read a few posts after doing a search on the ttforum the water pump seems very likely.  Should this be happening to a  car with only 20,000 on it? Though it is 4 years old.
 

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I had this and it turned out to be the sensor in the coolant expansion
tank, ?10 later and 1/2 an hour self fitting bean great ever
since. may be worth a look.
 

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Discussion Starter · #10 ·
I just got off the phone to my mate who's a mechanic and he reckoned it sounded like a sensor in the coolant tank. Cheers for the help so far lads.
 

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if it the car is actually getting hot then its the water pump most likely, as above, the impellors age and crack over time.

thats about a ?300 job from a specialist i believe, maybe less?

if the engine isn't getting hot then its just the coolant sensor (on yours its easy to find, do a search on it or check the thread on common posts on vwvortex, check the diy forum on here for the link). the sensors do different things, mine flicked from 90 to cold but some peoples go all over the place. its a common fault and the part is around ?25. yours is a lot easier to change than mine, mines in the depths of the engine [:D]. still, it took me around 30mins to change it.

good luck!
 

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Discussion Starter · #12 ·
If the engine was actually getting hot the temperature dial wouldnt drop from about 110/120 back down to 90 in about 10 seconds would it?  It's going to stay hot for quite a while surely.  The coolant hadn't boiled over at all or lost any coolant and when the AA map took the cap off it wasn't boiling.  Within about 100 metres and 10 seconds the temperature dial had gone up about 20C and straight back down.
 

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yeah no worries, its just your sensor then. the stealers know all about it, say you've got a dodgy temp sensor. the replacement has a green base to it over the standard black one.
 

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Hi andrew, listen, my car is doing the exact same thing, it started on the bank hoilday... temp shot up to nearly 130!! pulled over within 10 sec of turning the engine off and just flicking the ignition on the temp was back to 90???? go 2 miles down the road it shot back up again..

Rac didnt know what was wrong and they wont tow me back home (but thats another story!!)

After getting my car back home, the following day i changed the thermostat as some pipes where hot the others cold, tested the the thermostat in hot water and it worked, so my dad came round to have a look, found out the pipe going into the heater matrix was read hot while the exit pipe was cold, so he took the exit pipe off with the engine running and ive got no water at all coming out of the matrix!!! but water going in, so it looks so far like my heater matrix is blocked and stoping the circulation of the coolent... iam hoping my new matrix is gonna turn up today (fingers crossed)

So check the exit pipe on your matrix first to see if your getting water flowing in to and out of your matrix.
 

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Do not drive it at all.

I am willing to bet it is your water pump that has disintergrated. It happened to me exactly the same and it destroyed my radiator to, because I carried on driving a little bit.

Go and get it fixed.
 

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Discussion Starter · #16 ·
It was the Water Pump, its being fixed tomorrow at the dealers.  I had to drive to the dealers this morning and it went ok, they tested the radiator, fans, thermostat etc and they were all fine so I'm hoping no more damage has been caused.
 

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mines doing exactly the same, has been since sat and I've done about
100 miles since then! Think it's time tog et mine booked in and hope
it's not stuffed the radiator too! My car won't blow hot air out of the
heater either now, is this symtomatic of the same problems with the
water pump?

Still, I'm on my first water pump and cam belt and I've done 85k so could be worse I suppose.
 

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Mine did it on about 115,000 miles... The blades on the pump are so rubbish that they disintergrate inside the sytem and no longer work. I believe the replacement part is made of a stronger material!
 

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Andrew was some of your water pipes hot and the others cold? as iam worried my pump has gone now, but i still need a matrix as it seems blocked too.
 
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