Mercedes Benz repair: coolant leak at thermostat housing bolts, mercedes benz 300sel, coolant leak

Question
Having recently completed the daunting task of installing a new waterpump on my 1991 300sel,thought the task was complete until I noticed there is coolant leaking from the bolts that secure the thermostat housing to the water pump.Have tried to seal the new o-ring with sealant and put sealant on the bolts.Can't stop the slow leak and don't know what to do.
Should I get a new housing and o-ring or is there a quick fix I can employ?Would love to get rid of the cooking coolant smell...thank you for your answer

Answer
After looking over the part, suggest remove the pump and replace O ring.
http://catalog.eautopartscatalog.com/mercedesshop/sophio/image.jsp?title=Water%2...

There are a couple of questions:
#1. Did you torque the water pump bolts?
#2. Did you replace the water drain hose,lower drain hose, and o-ring = Water Pump Kit.

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1991 Mercedes Benz 300SEL
Part: Water Pump Kit
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=merc...