Land Rover Repair: Overheating, coolant level, air bubbles

Question
2000 TD5 SeriesII Auto.Blocked radiator replaced 3 weeks ago. Still overheating. Initial diagnosis 'airlock' possible headgasket. w/pump appears to be working. Test for CO2 in header tank - no indication. Top hose (with bleeder screw) getting fairly hard. No visible leaking - replaced heater hose following discovery of hole where it had obviously been rubbing against engine cover.
Normal temp. being reached after c4/5 miles. After about 10 miles @70 m.p.h temp needle begins to rise towards red. Similar boiling after 3/4 miles in 2nd/3rd at circa 2500-3000 revs. Replacing 5 litres + per day

Answer
Hi Fergus,

from a cold engine, remove the reservoir cap and start the engine.  Let the engine idle and watch to see if air bubbles appear in reservoir.

Normal method of releasing airlock is the above.  Keep the coolant level at the proper level.

Too much fluid is being lost.  Where is the fluid going?

Don't drive the Disco with an overheated engine. The cylinder sleeves can drop (welds fail) and if that happens the engine is scrap.

Consider pressure testing both the rad and the cooling system.  Most local garages can do this.

Best of luck,

JohnMc