Diesel Pump

Take it to a diesel specialist. There's far too much you can c*ck up in there, especially in regard to calibration, to DIY without the proper test gear.

On an M-plate this should be the lucas pump. From experience it's normally the cold start shaft near the bottom of the pump that leaks. It has been a couple years since I replaced the seals on one of these pumps, but from what I remember, once the pump is off, it is a fairly straight forward job. Any decent Diesel Injection specialist will supply the required seals (if they try to sell you a complete cold start unit, just walk out), if you can tell them the pump make + model no.

The main thing to remember is that the pump timing is adjustable on the lucas pump, by way of elognated bolt holes where it bolts to the front plate. The easiest way to maintain the timing is to remove the pump complete with the support bracket where it bolts to the side of the engine block. Ensure that you don't move the bracket in relation to the pump. Then when it comes to refitting the pump, put the bolts into the front plate, tighten them enough so that the pump can still turn on the front plate, bolt the support bracket to the side of the engine block, and tighten the front plate bolts.

Moray

There is a common fault on a lot of Transit pumps with the bush where the throttle control goes through the top of the pump. If that's where it's leaking from, you can take off the top plate and get an engineering shop to machine in a new bush. Otherwise buy a new top plate, (fairly pricey).