Recently the coolant warning came up just before our trip to Cornwall, so I refilled it, drove all the way there with no problems.

 

The coolant light came on again a couple of days later so I topped up again.

 

I've been 2-3 weeks with no warnings (and a reasonable amount of driving too) but this morning it came back again.

 

I'm sure if there was a hole in the radiator I'd be able to equate water loss with driving time, so any other ideas what could cause irregular loss of coolant?

Check if water pump is leaking.

Car has done 103000 miles so to be honest it could be anything from a perished hose to a water pump.

Does it relate at all to times when the car's been doing climbs that need downshifts? (for example, Kirkfield Bank)

Does it relate at all to times when the car's been doing climbs that need downshifts? (for example, Kirkfield Bank)

no, not that I can tell. Just been on the flat for the last week or so.

 

This morning I backed the car off the drive and just as I was about to pull away, the warning went off. I pulled back on the drive and noticed a small damp patch under where the car had been sitting, but I didn't have time to look to see if there was any wet spots in the engine bay. TBH modern engines are so tightly packed I don't think I'd be able to see any.

no, not that I can tell. Just been on the flat for the last week or so.

 

This morning I backed the car off the drive and just as I was about to pull away, the warning went off. I pulled back on the drive and noticed a small damp patch under where the car had been sitting, but I didn't have time to look to see if there was any wet spots in the engine bay. TBH modern engines are so tightly packed I don't think I'd be able to see any.

Ah, that probably rules out the mechanism I was thinking of where coolant is being blown out through the expansion bottle under high torque low speed and hence high coolant temperature conditions.

What engine is it?

What engine is it?

2.0 Diesel CR170

Sounds like the same symptoms as the water pump leak I had a couple of years ago. It lost coolant pretty slowly initially but the leaking rate increased over the couple of weeks between the first warning and getting it sorted.

 

Thanks to the splash cover under the engine catching most things that drip from underneath, even with the water pump leaking coolant there's still a reasonable chance the wet spot on your drive was from the aircon. I never saw a drip from my car, but shining a light down into the engine bay I was able to see some wet on the cover. If this is the problem get the timing belt done at the same time as it has to come off to remove the water pump anyway.

 

The good news is the job is surprisingly cheap on the CR170 engine. I was quoted around €370 by the garage I bought the car from, but they ended up doing it under warranty as the leaking coolant had contaminated the belt.

Edited 7 September, 20169 yr by psycholist

I drove home from work (7 miles) and spent a few minutes lying underneath the car on the drive with the engine running. There was plenty of water coming out but it was room temperature, not hot like you'd expect if it was coolant. I'm assuming it was condensate from the aircon?

The water pump on my previous twindoor TSI was beginning to seep. It drained out a whole expansion tank whilst I was in Thailand on business!

I never did get it replaced as I traded it in. Just topped it up every 3 or 4 weeks

I've also had to have a replacement water pump on my 2013 Superb FL, as has been mentioned above it drips and collects in the engine under tray, so not always noticeable on the ground.  

While the water pump was being replaced I also had a new cambelt and tensioners fitted to save costs later on.

Well at 103000 miles the cam belt isn't too far away, so that may well be the solution.

Well at 103000 miles the cam belt isn't too far away, so that may well be the solution.

 

120k is it due?

120k is it due?

That's my assumption.

My S2 got to 116k and to be honest I can't remember if it had the cambelt done - I think it did around 110k

I drove home from work (7 miles) and spent a few minutes lying underneath the car on the drive with the engine running. There was plenty of water coming out but it was room temperature, not hot like you'd expect if it was coolant. I'm assuming it was condensate from the aircon?

Ignoring any contaminates picked up from the condenser surfaces, aircon condensate is freshly distilled water, which is very unlike used coolant (colour and smell for example).

I'd say get the pump and cambelt changed. mine has done 115 k at 2.5 years old , is the cambelt 120 / 125 or 140 ?

Ah, that probably rules out the mechanism I was thinking of where coolant is being blown out through the expansion bottle under high torque low speed and hence high coolant temperature conditions.

Would that be solved by replacing the tank cap? Even though it's done up as far as it'll go it seems loose? There does also seem a correlation between hard driving/acceleration and water loss. A gentle trundle down the motorway doesn't seem to loose water.

Mine used some water on holiday towing the caravan topped it up and have had no problem since. However it was in the garage last week for new tyres and the mechanic told me there is a small leak in the bottom corner of the radiator, I read on this site that it is quite common for this to happen so its worth checking that.

Would that be solved by replacing the tank cap? Even though it's done up as far as it'll go it seems loose? There does also seem a correlation between hard driving/acceleration and water loss. A gentle trundle down the motorway doesn't seem to loose water.

It might do; if tank caps are still the "under £10" items they were the last time I needed one it's worth a try.

Check for residual pressure in the expansion tank first thing in the morning before starting the engine.

Check for residual pressure in the expansion tank first thing in the morning before starting the engine.

Being a bit dumb, but how?

 

In any case, I'm selling it to a trader tomorrow. I'm getting a company car in a few weeks and I wanted rid before the problem became serious - even if it turns out to be something simple like a cap or a hose.

Take the cap off and listen for the hiss of escaping gas!

Usually a sign of something getting into the coolant system that shouldn't be there.

Take the cap off and listen for the hiss of escaping gas!

Usually a sign of something getting into the coolant system that shouldn't be there.

Thanks. I'll bear it in mind for future use. As I say, it's going tomorrow anyway.