Rank: Guru
Rating: 86%, 101 votes
On the bosch design the water has to fill up to the proper level and then it trips a switch on the heater housing when the water starts pumping. The funny noise may be a lack of water coming in the valve.-you can check this by adding a little water in to see if it pumps stronger. In this case you need a fill valve. If it is a problem with the pump or the heater assembly it has to come out of the cabinet to check this. Not easy for most people to do.