Do a leak down test / apply low pressure air (say 5 PSI - you need low pressure high volume!) via the glow plug holes to determine where most of the air is escaping. You should get a much better idea of engine health this way - don't forget to rotate the engine by hand so that the valves are closed on each cylinder before you check for leaks.
When rotating these engines you need a 27mm socket for the crank shaft pulley. Do not turn these engines over on the cam shaft pulley - do not turn them in an anti-clockwise direction (taken as you stand in front of the engine {in the car} looking at it) as the timing chain can snag if spun the wrong way.
Let's hope it is just valve stem seals.
EDIT:- you are better off removing all the glow plugs before doing this type of check (compression test included) instead of tackling the job via the injectors as once removed the little heat shields that sit under the injectors should be replaced.
When rotating these engines you need a 27mm socket for the crank shaft pulley. Do not turn these engines over on the cam shaft pulley - do not turn them in an anti-clockwise direction (taken as you stand in front of the engine {in the car} looking at it) as the timing chain can snag if spun the wrong way.
Let's hope it is just valve stem seals.
EDIT:- you are better off removing all the glow plugs before doing this type of check (compression test included) instead of tackling the job via the injectors as once removed the little heat shields that sit under the injectors should be replaced.