I've got a TD5 90, I've got an oil leak, it ends by dripping at the bottom of the bellhousing but seems to be running down the left hand side of the bellhousing and it's all damp and oil on the side of the sump and just above the sump too.

The back of the engine is dry so I don't think it's the rocker cover nor the fpr as it's defintely oil. You can't see the oil leak from above the engine, only underneath and to the side.

Any ideas? My only guess is the sump gasket but can't understand why it's damp above the sump.

Give it a really good clean, dry it off with paper towels then take it for a run and check with a small mirror - you should be able to see the source of the leak.