Poppie, my '82 1.9TD Westy has a small air leak at the injection pump shaft. I can see minor bubbles in the Diesel return line to the tank. It also makes starting harder (takes a few cranks to purge any air in the pump housing), but thankfully if doesn't leak Diesel out on the timing belt since it is before the vane pump and thus at a slight underpressure. I lived with the airleak for a month, but now want to fix it.

I was hoping for some advice for if it is a good idea to replace the Diesel injection pump input shaft seal with the engine in the van. The pump is nearly new (only 40kmiles) so little point to send it for a full rebuild now).

My plan was to:
Position everything as for the timing belt change, locking the cam and pump pulley with the respective bar and pin.

Scribe a precise mark for the injection pump pulley position. (tricky part a)

Remove injection pump pulley. It has a woodruff key so goes back in the same orientation relative to the internal pump shaft.

Pry out old seal with screwdriver. Push in new seal. (Any reason this would be difficult?)

Now put injection pump pulley back on and (tricky part b) try to get it locked up in the same position as before.

Proceed with timing as usual.

Any tips for where and how to mark and re-align the pulley to pump position? (tricky part a and b)

Or is there a better way to replace the injection pump input shaft seal?

Thanks,
Martin