Take the inlet pipe off the cold side of the turbo. You will see the end of the shaft and the impellor blades. The shaft runs on a film of oil and when the engine is off there is a small amount of play in the shaft. If there's a lot of oil in the housing, then the seal might be leaking and this is specialist work. Other turbo problems can be wastegate stuck or the actuator mechanism not working due to a leaking diaphragm - generally you would have noticed if the turbo wasn't working becuase your truck would be gutless and slow. If you want to check boost pressure you will need to fit a boost guage in line with the boost pipe from the turbo to the wastegate actuator. The boost diaphragm on the top of the injector pump can stick or split, which will affect the turbo, and these can be stripped and cleaned/replaced. Have you still got the EGR valve fitted to the exhaust manifold? These just about always stick in the open position and the result is a heavy layer of 'marmite' in the inlet manifold. This has the effect od restricting air flow into the engine and making it gutless/smokey. The intercooler also gets clogged with the inevitable engine oil that gets into the air system, so these have to be removed and cleaned out. The oil seperator on the side of the rocker cover also gets blocked up and this can cause excessive oil into the intake system.
Les.
