High mileage: With this comes low compression due to worn cylinders/rings and worn, leaky valves. A compression tester should give a minimum of 130psi for a standard Series Land Rover petrol engine and fairly even readings. Worn piston components can be diagnosed by repeating the compression test with a few cc of oil in the cylinder: If compression is improved, cylinder components are worn, otherwise valves are leaking.
Spark plugs: If examining the spark plugs finds them with black deposits on the electrodes, then the engine needs decarbonizing. Shining a torch into the cylinders will help to assess the condition of the piston heads.
Accelerator linkage: The mechanical linkage from accelerator pedal to carburettor has a Mechano-type design, with several joints relying upon a friction fit. You may not be getting full accelerator pedal movement transmitted to the carburettor.
Air filter: The standard oil bath cleaner of the Series Land Rover should not be overfilled and the large connecting hose checked for internal collapse.
Fuel pump: Pump may not be delivering sufficent fuel, for petrol engines, disconnect at the carburettor end and pump into a container to assess flow rate (CARE!).
Valve timing: Listen for clicking sounds from the rocker cover and check the tappet clearances are as they should be.
Binding Brakes: If the wheel centres feel warm to the touch after a short drive, with not much use of the brakes, then the brake shoes may need backing off a bit. Jack up the wheels to confirm and adjust as necessary.
Slipping clutch: The clutch driven plate may be glazed or oil contaminated. The free clutch pedal movement may be incorrect or the clutch master cylinder pushrod may have incorrect free play.
Engine overheating: The cause of the overheating may be cooling system related, but it could also be incorrect ignition timing or weak fuel mixture.
Tyre pressures: Seriously under-inflated tyres can cause a Series Land Rover, with a standard engine, to lose more of what little power it has.
Recent overhaul: Unlikely, but if the engine has been recently rebuilt and wrong bearing clearances set-up then power will be wasted over-coming more friction.
Distributor problem: The contact points may not be set accurately, or the surfaces badly pitted. If the distributor has high mileage then it may be possibe to move the central shaft sideways a little, making accurate ignition timing impossible. General wear of moving parts in the distributor has a cumulative effect on accurate ignition timing and hence engine power output.
Coil: It could be developing a fault. The best test is to substitute a new one.
Timing chain: A stretched timing chain will lead to inaccurate valve timing. This may be indicated by white smoke on start-up which is very slow to clear up.
Fuel supply: There are several fuel filters enroute from the tank to the carburettor. If they are partially blocked they will restrict full fuel supply.
(To see previous homepages visit the Homepage Archives link)