aux. water pump & mono valve questions

I have a 1982 300SD. I did not have any heat all last winter and just had to replace the water pump, started to leak bad.
I don't know if my mono valve is working, as I never had any heat all last winter. Is it better to replace the whole mono valve or just replace the seals ?? I took it apart and the diaphragm does have a hole in it. I get air conditioning this summer, but nothing above the outside air temp. I assume this means my inside thermostat and controls are working ok.
I have seen other postings that refer to the aux. water pump. Where in my car is this aux. water pump?? I can not see anything that looks like a aux. water pump to me.
I would really like to have heat this winter, so I am trying to fix all the problems I can think of. I have only owned this car since July 2000.
I know these are simple questions to a lot of people, but I really need help to get heat.

Any help and input will be greatly appreciated.
Thanks!!
Martin

[stevebfl]

If the diaphram is bad then you should replace the mono valve capsule. The bad diiaphram will cause the valve to hydraulic closed while trying to operate and you will get little heat after possibly a brief spot of heat.