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Hello all.

I am hoping one of you gurus will be able to help me out.

I was cruising yesterday at 70mph and all of a sudden temp gauge light comes on. Then my heart sinks to a low it's not seen for a while. (I have a 98 S4 with 116k on the clock with good service history)

Open up the bonnet and the coolant is unusually low. I let the car cool down for 10 mins then fill her up to recommended limit. I set off again and temp gauge again starts to climb up. it was like this all the way home.

I have been told it could be a few things:

Water pump needs replaced
Temp sensor gone (not sure if this would be it if the coolant levels were not normal?)

Has anyone experienced this and could give me some advice or other causes?

Thanks in advance guys.

An unhappy Slax

Not experienced this myself however my money would be on water pump failure.
Did the pump get replaced with the cam belt service?

Do you have any visable leaks from under the car or split hoses/expansion tank?

HTH

Not sure if it was replaced when the cam belt was changed I would need to check with the garage/previous owner.

No visible leaks coming out under the engine bay. There doesn't seem to be any visible dampness that would be expected from split hose pipes.

Could it be anything other than the water pump? I have been told to replace this and to replace the belt it will be in the region of £500?

Thanks for getting back to me.

As Phil suggests the waterpump is suspect.
You get corrosion on the waterpump shaft. The bonding of the plastic blades on the waterpump fail, pump stops pumping !
To replace is its £40, but as suggested you may as well do the cam belt along will all the pulleys. £500 is about correct, make sure they use the correct bar/tool to time up the cams.
Dont drive it too much other wise you will have the head gaskets to do as well.

I don't know who the manufacturer is, but when I had the cam belt done, the garage wisely recommended a metal impeller pump to prevent this problem with the plastic impeller.

Was the hydraulic tensioner replaced when the cam belt was done? The cam belt only makes contact with the water pump pulley for a relatively small angle, so low belt tension can allow it to slip.

I would also check the cooling system for excessive pressurisation whilst engine is running or do a leak down check if you find someone with a pressure tester which can be applied to the coolant reservoir to be sure that a head gasket leak between cylinder and cooling system is not responsible.

From the service receipt it looks like the timing belt, auxiliary drive belts and any tensioners were replaced at 80k. I am looking to get it into the workshop ASAP so will ask about getting the coolant pressurisation checked too.

Thanks for all the advice.

water pimp..the plastic blade just sits there as the cambelt just spins the centre of the shaft..
if you aint got a leak anywhere thats prob ya problem..the aux water pump can leak but for the temp to rise you would notice a severe water loss..

Is a water pimp a person who gets ladies to sell water and take a profit?

no no no...a water pimp is a device that runs your money out of your walet...so you and your engine overheat...

Sounds very much like the water pump is knackered to me, as they are the exact same symptoms that i had when mine went 5 months ago

almost exactly the same as what happend to me this time last year, and that was the waterpump failure - Just dont do what i did and take it to Audi to have the work done... good job was done but it cost me virtually double what you've been quoted