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Hello. My car has started to mysteriously lower the level of coolant. I checked it today and the reservoir was empty (radiator was still full). It has had a new radiator top fitted about 5000 km's ago and I cannot see any leaks. There are no strange odours in the car, the carpets are dry etc... The only strange thing I have noticed is the pipe from the radiator to the reservoir is covered with a white powder-like substance.

Any ideas would be appreciated! It is going in for a service next week, but I am concerned by the strange loss of coolant when everything else seems fine.

Thanks.

Forgot to mention.... Apart from some fuel vapour when cold, no smoke/steam coming from the exhaust......

Maybe radiator cap?

G

you cannot always see the leaks and it is possible that it was not filled correctly. If you top up the reservoir and it still loses fluid then it will need to be tested. Check your oil to see if there is an sign of contamination with water.

Check the carpet inside, around the heater. If it is leaking there you should smell it, but best to have a close look especially if your 'green stuff' is mostly water ...

Noddycar wrote:The only strange thing I have noticed is the pipe from the radiator to the reservoir is covered with a white powder-like substance.

Probably nothing to do with the car but you could ask your mechanics what the hell they've been doing while they've had your car in the workshop.

Carpet is clear (not wet or turning green). Oil is clean. Can't see any indications of a leak around the radiator cap. Totally mystified! I have topped it up myself and am using quality coolant and distilled water.

Noddycar wrote:Can't see any indications of a leak around the radiator cap.

An old cap can fail to hold pressure which in turn let's the water boil and steam, which in turn can escape etc.

The pressure raises the boiling point etc.

Something to look at and cheap to replace if not just peace of mind.

G

Noddycar wrote:The only strange thing I have noticed is the pipe from the radiator to the reservoir is covered with a white powder-like substance.
Thanks.

That's a tell tale sign of leaking coolant. The white powdery stuff is the salts from the coolant all dried up, after the water has evaporated away. You should be able to trace the white powder to the source of your leak.
The finer the powder, the higher the steam to water ratio. Large clumpy salt encrustation indicates water drips, a fluffy coating of fine powder indicates steam.

The location indicates somewhere near the top of the radiator, maybe the cap, or the hose leading from the top of the radiator to the engine (water pump, I think).

If it's mostly steam coming out, then it's likely to be a fine crack in the radiator, or a hose joint/seal, which expands as the radiator gets hot, releasing all the delicious coolant.

The way to confirm this, is to take the car for a drive, get it nice and warm, and then pop the bonnet. If you're lucky, you'll see, or hear the steam/water leaking out.

Doesn't seem like you've taken a good look around at all.

raise your car, remove the undertray and inspect it and take a good look at the underside of the engine as it can be from any part of the engine, heater hoses at the back, heater return & radiator inlet on the exhaust side, water pump at the front.
Obviously can also be underneath the rad which you can't see as it's covered by the undertray.

Any chance you could post some photos? It does sound like you've got a leak somewhere, potentially an early warning of a more dramatic failure. What is the colour of your radiator top & bottom tank? If its brown or tan, its old and you could have a pinhole leak that's about to go bang. Do your radiator hoses feel soft/compliant or hard/brittle? If the latter, they're overdue for replacement.

Undertray is dry, no discolouration around the radiator that I can see, have tried running the car (hard) and then stopped to see if there is a leak - no success! Hoses seem OK. I am stumped. When I took it for a hard drive last night, the coolant level did not move and there were no obvious leaks. Which is why I am surprised to see sudden and coolant drops at other times.

I will bite the bullet and see if I can get the car into the mechanic today, rather than waiting for next week. Thanks for the suggestions - all good points, but if any of these are the cause, it is well hidden.

sounds like if the hose from the rad to the over flow tank is white then that hose is split or leaking somewhere
try a new hose !

Problem found..... Water pump is leaking. Time for a new one!

Noddycar wrote:Problem found..... Water pump is leaking. Time for a new one!

You found it! This is good news.