A3 Coolant Problem

[jonny1409]

Hello,

I wonder if anyone can give me some pointers / advice please ?

Basically I've recently bought a second hand Audi A3 (http://www.audi-forums.com/#) (51 plate - 66,000 miles) and it's been running fine for the last couple of months, although there was a coolant leak when I bought it so this was fixed as it was due to some problem with the radiator or pump or something (apologies, but I'm not technical as far as cars are concerned!)

Anyway, I've suddenly noticed oil patches on the driveway so it looks as though there is a problem there.
Also, the coolant warning light has started coming on the dashboard and the temperature gauge shows 120 once i've been driving for about 10 minutes.

I've topped up the coolant as it was showing under the minimum, but the next day, the same thing happened.

What is likely to be the cause of this ?
Is it serious ?

I'd appreciate any advice anyone can offer.

Thank you.

[kenney]

Are you sure it is oil,on the driveway and not antifreeze??.If the temp gauge reads 120 degrees the engine is surely over heating,and that could be down to a number of faults,coolant pump,head gasket,thermostat,cooling fan.

[jonny1409]

Thanks Kenney.

I've had it into the garage and he has pressure tested the car and found no leak !

There was oil leaking but this was due to the oil cap being missing (I knew this was missing and I had one on order).

I checked both the oil and coolant before driving it tonight and both are full.

However, I've just driven it and after about 5 minutes / 3 miles, the coolant light came on and the temperature gauge went up to 120.

Could the sensor be at fault, or is there definitely something else ?

[kenney]

If the engine temperature is in reality 120 degress,then the engine is overheating,and the fact you are loosing coolant,does also suggest it is overheating.The normal procedure,is first, to check,if there is any signs of exhaust gas in the cooling system,if there isn't,then the next step is to check the thermostat,and then the water cooling pump

[jonny1409]

I don't believe I'm losing coolant now - I think the spots on the driveway were the oil from the missing oil cap.

I filled it a couple of days ago and the level has remained the same (at least as far as I can tell)

There doesn't appear to be anything else in with the coolant (it's just a light pink colour)

How will I know whether the engine is really 120 degrees, or whether a faulty sensor is saying it is, when in fact it's not ?

[Issac Hunt]

Change (or test) the sensor first as its easiest and cheapest. If that dont fix it then you need a new water pump I reckon.

[jonny1409]

Thanks Isaac - how can I check the sensor ?
Is it something I can do myself, or will I need a garage to do it ?

[Issac Hunt]

You could test its internal resistance at various temperatures, easy if you know what to do.But if your removing it anyway, I would just replace it as they arent expensive.

[kenney]

Quote) I've topped up the coolant as it was showing under the minimum, but the next day, the same thing happened.?????????
Anyway,if the engine is running at 120 degrees you will not be able to touch the coolant hoses,or the top of the radiator,If you can hold your hand on the top radiator hose,for a short peroid,then,the engine is not running at 120 degrees