Much attention is given to the diagnostic aspects of black exhaust smoke emitted from either petrol or diesel engines. Less attention is given to the causes of white emissions and what the causes might be.
Whether your Series Land Rover is burning petrol, diesel or lpg, one of the products of combustion is water vapour. If the temperature is low enough then this vapour can condense into tiny water droplets that appear white - basically cloud formation. We almost always see this when a cold engine first starts up - at least in the typical British climate. The white coloration should disappear as the exhaust system heats up and allows the water vapour to leave without condensing.
Another cause of the white smoke though is incomplete combustion of whatever the fuel is in the cylinders. We tend to associate black exhaust with unburnt fuel but that is the extreme case of incomplete combustion. If most of the fuel is burnt then the exhaust appears as a 'lighter shade of black' or even white. It is important to npte here that "fuel" is whatever is in the cylinders that can burn and in some cases this can include oil and brake fluid.
So, if we have a white smokey exhaust when the engine is at normal working temperature then we have a problem. It could have a variety of causes:
1. Anything that can cause fuel to enter the cylinders too late and thereby not have sufficient time to burn can be a cause e.g. a stretched timing chain or incorrect valve timing; incorrect timing for the diesel injector or petrol ignition timing.
2. Series Land Rovers with servo brakes could have brake fluid leaking past the brake master cylinder seal and into the brake servo unit. From
here it can get to the inlet manifold and hence into the combustion chamber to become unwanted 'fuel'. This problem would be best observed in heavily congested traffic when your right foot is going from side to side as well as up and down! So if the engine runs rough in such situations consider this as a possible cause. Check if the brake fluid level is dropping. The solution of course is to overhaul the brake master cylinder.
3. There could be coolant getting into the cylinders via a damaged cylinderhead gasket. This will cause rough engine idling and significant loss of power. You may observe air bubbles in the neck of the radiator when the engine is running and revved slightly (REMEMBER don't remove the radiator cap if the engine is hot).
4. A small amount of oil entering the combustion chambers may be mostly burnt as 'fuel' and result in white exhaust emissions. Only later, if the amount increases, will the exhaust become darker. So check for perished, or leaking valve stem oil seals, reduced engine compression or glazed cylinder walls.