Dismanteling a Johnson F7B-903 impeller cooling pump
 

I hate when this happens: the impellerpump starts to leak seawater on
my engine and everywhere in my bilge.

On my Peugeot 60hp marinised diesel I have a Johnson F7B-903
impellerpump delivering seawater to the heat exchanger. The water- /
oil- simmerrings in this pump start to leak after a few hundred hours.
I had the pump revised/overhauled by a machine shop for good money
only 50 engine hours ago but now I have the same problem again.

I guess I am going to take the shaft out and polish it till it shines
before I put in new oil-simmerrings

Does anybody know if I can dismantle this pump without any
sophisticated tools like a hydraulic press or whatever?
Can I push the shaft out by hand or with a plastic hammer?

Thanks for your time... Any advice is highly appreciated...
Len.