The Grundfos JP6 jet pressure pump takes a mechanical seal for a 12 mm shaft. This replacement seal suits the JP6 (also labelled JP6-B) and is the same seal used in the Grundfos JP5. Like most small pump seals, it works as a rotating face on the shaft running against a stationary seat in the pump body. Measure your shaft or old seal to confirm before fitting.
How to tell you have a Grundfos JP6
Check the rating plate on the motor. The model shows as JP6 or JP6-B. It is a single-phase jet pressure pump with a 1.06 kW motor, typically used to draw water from a well. If your plate shows JP5, the seal is the same, and it has its own Grundfos JP5 mechanical seal listing.
Signs the JP6 seal has failed
A mechanical seal wears slowly, then starts to weep. Change it as soon as you see a leak. Water that tracks along the shaft into the motor end is a common way motor bearings get ruined.
- Water dripping from the gap between the pump body and the motor.
- The pump cycling on and off when every tap is closed.
- A damp patch, scale or rust streak under the motor end.
- A seal that has already leaked once, even if it has since dried up.
Pumps that share the Grundfos JP6 seal
The same 12 mm seal fits the Grundfos JP5. It is also used in the Grundfos SPK, Lowara BG, Lowara SG, early Lowara C Series and Saer FC20, which don’t have their own listings here. The seal is also sold on its own as our 12 mm Grundfos JP5/JP6, Lowara and Saer pump seal.
Fitting a new seal in the JP6
Isolate the power and drain the pump before you open it. Keep the new seal faces clean and dry, and don’t touch them with your fingers. Lubricate the rubber parts with soapy water rather than grease, and press the stationary seat in squarely. Don’t run the pump dry after fitting. Prime it fully first, because even brief dry running can damage new seal faces.
If the motor has also been slow to start, the Grundfos JP6 service kit pairs this seal with the run capacitor so both jobs are done with the pump open once. Seals and kits for other models are on the Grundfos service kits page.
Before you order
Check the old part before fitting: match the size of your old seal.
Capacitor details for this pump: Grundfos JP6 capacitor guide.