If the Webasto is locked out it shouldn't start up at all, unless you've done a hard reset on it. If it starts up and gets hot though, clearly all the burning-related pieces of it are working, and there's no issues with the Webasto's glow plug, etc.

The water pumps on the Webasto Thermotop units are usually pretty good - I've got several on a boat, and no issues in 15 years of ownership. I did buy a spare water pump several years ago as I suspected a problem with one onboard, but turned out just to be a slightly low coolant tank and a bit of air in the line, and no issues ever since. If you do need one, at the time the cheapest place to buy a genuine Pierburg pump was 123spareparts.co.uk, just under £100 from memory.

As it happens I just completely stripped the boat Thermotop C heater this weekend as a glow plug had failed (after 15 years of usage heating radiators and hot water tanks, so not exactly bad!). Again, I bought a few spare parts after seeing a fault a few weeks ago, as one symptom on mine was the pulsed diesel pump not activating, so given a new one's only £10 I ordered one anyway, along with a spare glow plug. But reading further before getting back to the boat, these units are vaguely clever on startup at checking things, and if the glow plug isn't sensed to be working, then it won't kick in the diesel pump, which is the fault I had. Similarly, if there's voltage problems, it will struggle with startup, and I think it supposedly checks the air fan and water pump. If the water pump fails, or gets a bit of an airlock, the heater might startup and get hot but then shut itself off after a few mins as a sensor detects it overheating - that's certainly the symptom I had a few years ago when I had a bit of air in the radiator circuit and needed to bleed it.

I haven't got one on my L322, but I assume it's a right pig to get at/remove? Thankfully on our boat it's very sensibly installed, and this weekend I managed to take it off, replace the glow pin and remount it in about 30 mins, and then ran it for 4 hours just to make sure it really does work now! If you can reach it, you might be able to feel the water pump running. If you can get at the top of the heater, the water pump connector is towards the rear of the connector plugs under a removable black cover - you can just send 12V down it to make sure the pump is working okay.

Thanks for this info guys.

I think my 1st port of call this coming week will be to get my battery tested.

2nd port of call will be re areaging the dreaded trip from Southampton to Birmingham to get this thing fixed properly.

Having said that would be great if battery was starting to fail and a new one fixed it

Don’t think I’m ever that lucky though  Regards

Daz

-------------------------
2011 (61plate) 4.4 tdv8
sumatra black

previous cars

e46 m3
e53 x5

Can I assume you don't have an IID or any other diagnostics that can ask the FBH how it is? Land Rover Addict
XXXXXXXXXXXXXXXXXXXXXXX

Previous
XXXXXXXXXXXXXXXX
2009 5.0V8SC Autobiography
2006 4.2V8SC Autobiography
2004 4.4V8 Vogue

You are correct sir Regards

Daz

-------------------------
2011 (61plate) 4.4 tdv8
sumatra black

previous cars

e46 m3
e53 x5

If someone that lives close has an IID they can use it to read your codes. They can't do anything else (apart from clear them), but they can read your codes  Land Rover Addict
XXXXXXXXXXXXXXXXXXXXXXX

Previous
XXXXXXXXXXXXXXXX
2009 5.0V8SC Autobiography
2006 4.2V8SC Autobiography
2004 4.4V8 Vogue

Yeah that would be good.

Fallout to anyone that can help??? I’m in Southampton.

Just had the battery tested and it’s showing 89% health?

Apparently the agm battery’s never charge to 100%?

Joe90 has mention in his sig of IID tool available in Hampshire - not sure of exact location but might be worth a PM - at least he's in the same county as you!

Edit: Winchester according to profile 09 RR Westminster 3.6TDV8 - Stornoway Grey / Black interior - now gone (sad face)
Nissan X Trail 1.6TDCi Tekna
Fiat 500 1.2