Land Rover Repair: Overheating Discovery Series II, discovery series ii, water temp gauge

Question
Hi Nigel,
I am writing from Fiji. For almost an year now, I have been trying to fix the
overheating problem in my Discovery ( 90,000 km ). The coolant boils and is
pushed out though the over flow pipe in the radiator over flow bottle.
1st we removed the thermostat and made pipes to allow bypassing the
thermostat. then we changed the head gaskets and now we have taken off the
radiator and had it serviced but problem remains............ coolant boils out of
the bottle.
I don't know what else we should be looking at to sort out the problem. The
water temp gauge does not go above 1/2 level but coolant drains out like an
open tap.
Thanking you,
Anand

Answer
The radiators on this car cannot be serviced.  If there is a problem with the radiator, it needs to be replaced.  I suspect your major problem is porous liners (cylinder bores).  These can sometimes be replaced, at a good machine shop, but you may be better off simply replacing the whole short block.