The RPD Diaphragms are used on all RPD (Harben) pumps, also known as P Type pumps. There are 6 diaphragms in a 6 cylinder pump and 8 in an 8 cylinder pump. These diaphragms can split over time from wear and tear, but they are also the first component to be impacted if the pump freezes.
The general symptom that occurs when diaphragms require replacement is a loss in pressure, often due to a pinhole leak at the tip of the diaphragm. This results in the pump pumping oil out of the crank case into the water stream which creates visible oil in the water coming out of the sewer hose. Check level of the oil in the pump to determine if there has been a reduction in pump oil. If one diaphragm is damaged, there are likely others, so it’s recommended to inspect each diaphragm for replacement.
