Derbi Senda 50cc water pump

[nealsam]

I Think the seal has gone on the water pump. I tried to remove it but it wont budge, is there a knack to it?

[cheekythomas]

No special technique, just unscrew the impeller, then push the shaft out of the case, then tap out the seals and replace with new.

Inspect the shaft for any wear or grooves where the seals fit, and replace if needed.. always fit a new impellor, they are dirt cheap.

Just watch out which waterpump kit you buy depending on the engine being used, the old engine had water pump above the oil pump, the new engine has it the other way round.