Series Land Rover - Engine won't start when hot
For petrol engines, we are assuming here that there is a spark at the spark plugs and fuel is actually reaching the carburettor. Check these two items before considering the faults outlined below.
You need to decide whether the starting problem only occurs when the engine is hot and if the engine has infact been overheating. Otherwise, the starting problem could also be due to any of the standard starting problems associated with a cold engine. See the October homepages in the archives section for more details.
Original Series Land Rover diesel engines
Diesel engines generally do not present starting problems due to overheating. If there is overheating then the starting problem will probably still be present when the engine cools down. You need to check for all the normal problems associated with a Series Land Rover diesel engine not starting as it should i.e. fuel and air restriction problems. See the October homepages for more details.
Original Series Land Rover petrol engines
Check that the cold start linkage is not jamming in the partly open position thus providing too rich a fuel/air mixture. If this was the case, then you should also find dry black powder deposited in the tailpipe, rather than having the grey appearance it should have. This black powder appearance is also an indication of a poorly adjusted carburettor or restricted air filter.
A warm engine is normally more likely to start than a cold one. So if there is a problem with hot starting then it may well be a carburettor problem. There are many problems that can occur in a carburettor e.g. float level being set wrongly causing flooding; float damage; partially blocked jets; leaking gaskets etc. The carburettor would need opening and overhauling with a suitable kit. SU carburettors can develop a weak jet spring causing the jet tube to stick. Zeniths can leak internally.
If the engine has actually been overheating, as indicated on the temperature gauge, then petrol could have vapourised in the fuel line. Simply allowing the engine to cool for 30min should enable it to start again. Repeated attempts to start an overheated engine are futile and will just run down your battery. You can raise the bonnet and run a damp cloth repeatedly over the fuel line, mechanical pump and carburettor to help speed the fuel cooling process but don't allow water to drip onto the very hot exhaust outlet else it could crack.
An engine which overheats can mean that the ignition timing is set wrong or that too much sediment has built up in the engine block and is restricting coolant flow. Could also be due to the carburettor set to too weak a fuel/air mixture.