Oily plugs and smokey exhaust

[Bedders]

1990 T25 with a 1.9dg 110k miles engine is showing these symptoms. The plugs are oily on the threads on the left cylinder bank only, but look ok on the right side.

Also the the carb seems oily when I inspect it which I think is excess oil through the breather . This seems to cause the engine to idle poorly and cut out. A squirt of carb clean will 'fix' this problem for a few hundred miles.

The most likely explanation is worn piston rings/cylinder bores.

Are there any other possible causes?

[SILVERFOX2013]

hi i would say so but could ilimnate one or three things first 1 could be man fuel pump if fitted leaking fuel into oil 2 timeing to much advanced un burnt fuel ect 3 check state of igntion parts good luck in finding solution