Done a bit of searching on this already, a lot of people seem to say it's likely to be the water pump. I got a replacement pump (and thermostat, as they also say to do that at the same time), but then further research seems to suggest it's a cam belt off job - is that right? Think that might be beyond my capabilities! 

Yes the water pump is driven by the cambelt

Just now, Tech1e said:

Yes the water pump is driven by the cambelt

 

Gotcha. Any other likely causes of a leak? How do you go about diagnosing?

Pressure test the cooling system and see where the coolant is coming out.

18 minutes ago, Tech1e said:

Pressure test the cooling system and see where the coolant is coming out.

 

With something like this? 

 

https://smile.amazon.co.uk/FreeTec-Cooling-System-Coolant-Compressed/dp/B07PLHZWBD/ref=sr_1_3?crid=2QQ4MQ64RF3Q4&keywords=coolant+pressure+tester&pd_rd_r=c63dbea0-319f-43a4-a968-9a7a9fb48c86&pd_rd_w=tZ5wb&pd_rd_wg=F6o3R&pf_rd_p=ea5f5568-a2c9-42c2-9778-dac82ffbdd53&pf_rd_r=9T99NKWAV2PXP8QAE3TB&pid=Nd4NGjd&qid=1568709646&refinements=p_76%3A419158031&rnid=419157031&rps=1&sprefix=coolant+pressure%2Caps%2C245&sr=8-3

Yeah, that's a pretty comprehensive kit and will fit many different types of vehicle.

Cool thanks. I guess I have to fill it up with coolant before testing.

Any other tips? I'll probably make all the idiot mistakes ...

@TomD77 - Well general advice here:-

 

1. If the cambelt needs replacing, replace the water pump at the same time, because the likely life of the impeller is about 1.5 cambelt changes, and when you have to pull the timing assembly down again you'll save money.
2. If there's an obvious water stain, investigate that before bothering with a pressure test.
3. Most likely places for a water leak are actually the expansion bottle, the hose joints and the radiator rather than the water pump.

1 minute ago, KenONeill said:

@TomD77 - Well general advice here:-

 

1. If the cambelt needs replacing, replace the water pump at the same time, because the likely life of the impeller is about 1.5 cambelt changes, and when you have to pull the timing assembly down again you'll save money.
2. If there's an obvious water stain, investigate that before bothering with a pressure test.
3. Most likely places for a water leak are actually the expansion bottle, the hose joints and the radiator rather than the water pump.

1. Had the cambelt done at 80k, so may need doing (now 130k) but I'd rather not if possible! If I can get another 30k out of the car I'd be happy ...

2. Obvious stain on the drive 🙂 ... could tell where it was coming from

3. Back to the pressure test?

 

Also seen this: 

 

https://smile.amazon.co.uk/KALIMEX-LTD-KSEAL-Coolant-Repair/dp/B001QT9KO6/ref=sr_1_11?keywords=coolant&qid=1568710579&s=automotive&sr=1-11

 

Seems to get good reviews? Guessing it won't work for certain kinds of leak though.

Don't bother with Kseal, its a bodge and will only cause further issues.

4 minutes ago, TomD77 said:

Also seen this:

OK, I actually read the advert.

 

Question - Why does it have tyre rating data in the advert?

 

Note that the makers only claim it will be effective for "holes up to 0.75mm diameter".

 

2. You say "obvious stain on the drive", but that confirms that there is a water leak from somewhere, or not because if you use the aircon (Climatronic in Auto mode) then you get the frost melting off the chiller and dripping onto the drive too.

3. My point was that it's sometimes possible to see a water stain on the engine or radiator and trace the leak to a component or joint without a pressure test.

How much is it losing how quickly?

 

Mine had a coolant leak last year which turned out to be from the coolant temperature sensor housing. It was quite a slow leak though - no visible steam and I missed it when looking from the top of the engine.

 

Have you looked around the engine, radiator and underneath to see if you can tell where the leak is? It might be obvious without needing to do a pressure test.

Edited 17 September, 20196 yr by petrolbloke

1 hour ago, petrolbloke said:

How much is it losing how quickly?

 

Mine had a coolant leak last year which turned out to be from the coolant temperature sensor housing. It was quite a slow leak though - no visible steam and I missed it when looking from the top of the engine.

 

Have you looked around the engine, radiator and underneath to see if you can tell where the leak is? It might be obvious without needing to do a pressure test.

 

I filled it up, and couldn't see an obvious leak with the engine running, but by the morning it had all leaked out. You're right though - I should probably try that again

7 hours ago, KenONeill said:

OK, I actually read the advert.

 

Question - Why does it have tyre rating data in the advert?

 

Note that the makers only claim it will be effective for "holes up to 0.75mm diameter".

 

2. You say "obvious stain on the drive", but that confirms that there is a water leak from somewhere, or not because if you use the aircon (Climatronic in Auto mode) then you get the frost melting off the chiller and dripping onto the drive too.

3. My point was that it's sometimes possible to see a water stain on the engine or radiator and trace the leak to a component or joint without a pressure test.

 

As per the last response - filled it up, and couldn't see an obvious leak with the engine running, but by the morning it had all leaked out, so defo not aircon. 

7 hours ago, KenONeill said:

OK, I actually read the advert.

 

Question - Why does it have tyre rating data in the advert?

 

Wow good spot ... clearly not paying attention with their listings!

@TomD77 - OK, you have a leak. A pressure test is a waste of money unless it helps you locate the leak, but the whole point of most of the postings is related to trying to find a leak without ever seeing the car!

Take it to a garage

Did you sort the leak??? Was it the coolant temp sensor??.. I have a leak at the moment and hoping it's something with an Easy fix