I recently purchased a 57 plate (Jan 08 build) dealer part ex Ka, and apart from a few bulbs and the standard Ka rust beginning in places it appeared to be a good car. Just over 60k miles and a decent bit of service history to go with it, although I did my own oil/filter/air filter change as soon as I got it.

After a week or two I started to notice it was losing a bit of water, not massive but noticeable when looking in the water top up tank. I kept an eye on it and topped it up when necessary. Then this past weekend I noticed the fan has started kicking in, and the car was running relatively hot (but I never got a temp warning light) so I decided to do a bit of troubleshooting. I started with the thermostat, and noticed that the entire thermostat housing was leaking quite visibly, so I removed that, cleaned the area and put on a whole new unit. While I took that off I noticed the thing was coated on the inside with what looks to be radweld, making me worry a little and it would explain why this isssue appears to be getting gradually worse if someone chucked a load in before they part ex'd it in.

Long story short after all that, the fan's still kicking in, the water pump seems to be okay as when I removed all the hoses to get to the thermostat housing and tested her she spurted everywhere. The only things I can think now are radiator issues, an airblock, or worst case a headgasket. Now the car does put out a little water out the back, not a massive amount, no oil in the water or water in the oil (no gunk) and power seems fine. I'm a bit stumped as to my next step and any help would be appreciated, thanks in advance.

The fan does not kick in till its way hot 105 deg. Take the radiator out and get it cleaned or recored.

To check the temp get torque plus android app (Englander one I think) and an OBD11 bloo tooth adaptor.

So it seems after dropping the car off at a local garage I trust, they narrowed the issue down to a pipe that runs from the tank of water, to the thermostat housing. It looks like some type of overflow pipe. Truthfully I wasn't that convinced but i've been driving it around all day and no sign of the fan kicking in or anything, so it may have just been something that simple. £45+ VAT.

Yes this hose can block with rust esp if no anti freeze is used. To check take off from radiator remove recovery cap from tank and blow

Funnily enough I did exactly that but assumed I couldn't blow through due to perhaps what felt like a non return valve. Which to me would make sense with it looking like an overflow pipe. But hopefully problem solved.