2008 Nissan Patrol Pricing and Specs

Worn glow-plugs will certainly make a diesel engine difficult to start and can easily contribute lots of smoke to the equation. But in reality, you could be looking at anything from worn or dribbling injectors, a blocked air-intake system, a worn fuel pump or simply internal wear in the engine itself. A worn turbocharger bearing or seal can also cause these problems, and don't forget about the simple stuff like a blocked fuel filter.

Trying to diagnose turbo-diesel engine problems from the colour of the smoke emitted is a hiding to nowhere and you'll inevitably find yourself changing perfectly good parts on a hunch and wasting lots of time and money. The best bet is to take the car to a diesel specialist and have the whole system investigated.

Four-wheel-drives like the Patrol tend to do big mileages, so you often see them advertised with overhauled or reconditioned engines. That’s not a problem provided the work has been done properly and quality parts used.

But you also need to talk to the seller and determine exactly what they mean by `overhauled’. A true overhaul will have included reconditioning the cylinder head, boring the cylinders, new pistons, new bearings, rings and even things like a new water pump and fuel pump. The receipts form the rebuild will tell the full story.

Our bet would be on the car you’re looking at having had a piston failure (number three or four piston) which was too common on the ZD30 engine. At which point you need to find out whether the engine was completely rebuilt, or simply had a new set of pistons and a new turbocharger fitted.

If it's fuel-injected pumping it won't make any difference, in fact it could confuse the computer and make it more difficult to start. Check the fuel pressure and depending on the result of that check the fuel pump.