Disco 2 V8 Overheat Nightmare

So, not used the disco in a while and as it lay sad and neglected on the drive I decided to get it running, clean it up and use it on our camping trip next weekend. Battery recharge and a clean had it looking and sounding lovely, a quick run round the block, hmm running a bit warm but topped up the reservoir and seems ok. Give it a treat and get it serviced so booked it in, drove it over to the garage this morning temp in the red and blowing out all the coolant!
Managed to get it to the garage and left it with them. Garage serviced the car and replaced the thermostat but whist the car will tickover all day and not overheat as soon as you drive it temperature shoots up and there's only a trickle of heat out of the heater. Garage did a sniff test and said there was no products of combustion in the coolant so looked unlikely to be head gasket. Managed to get the car home and have spent ages slowly refilling the system, burping it, venting it but still the same.
Though one strange thing occurred to me, when I fitted a new water pump last year it took ages to get all the air out and you could hear the water and air rattling through the heater matrix but this time all was quiet.
So decided to drop the water pump off and found the impeller wasn't being driven by the shaft. It looks like it's been shrunk on as there is no evidence of any weld. Worst thing is I cant remember who supplied it but I think it was a Britpart job. How any manufacturer can supply such rubbish quality parts is beyond me
I've learnt my lesson only OEM parts from now on.

Oh as a side issue whilst poking around the radiator I managed to break off a little plastic pipe on the top of the radiator right hand side, it is connected to the expansion tank by an 8mm pipe. I've capped off the pipe at the radiator and plugged off the other end to the expansion tank. Will the cooling system still work ok or am I going to have to get a new rad.
Cheers

Ian

Bleeds the radiator you will have a cooling system performing at below par without it. It may be possible to epoxy glue some sort of generic plastic pipe fitting in or something I would investigate that before writing off the radiator.

Just replace the rad there is no real permanant fix for that silly little bleed off pipe braking and to bleed the heater mateix properly pull one of the hoses to it insert garden hose and run until water comes out of the top expansion cap hole at the same time stick your finger over the pipe the heater hose was joined to.
Works every time for me

had an impeller come loose on a scana bus once not very often this happens but good detective work on your part to find it