Lowara 3SV mechanical seal leak: replace the seal kit, not the setting

That does not replace the service manual for your exact pump variant, but it does set the direction clearly. If the leak really is coming from the mechanical seal, treat the seal as a part to be replaced, not as a component to adjust by guesswork.

Check the leak source before ordering parts

Water around the motor-pump interface does not automatically prove that the mechanical seal faces are the only problem. Before stripping the pump, work methodically:

1. Switch off and isolate the electrical supply so the pump cannot restart unexpectedly.
2. Depressurise the system on both suction and discharge sides.
3. Dry the pump exterior fully so you can see where water first appears.
4. Watch the first leak point: shaft area, seal housing, flange, fitting, drain, vent or a nearby connection.
5. Record the full nameplate details: model, version, power rating, serial number and configuration.
6. Note recent operating conditions such as loss of prime, dry running, salt water, deposits, vibration or previous maintenance.

This step matters because replacing the seal will not fix a nearby pipe connection, a flange leak, trapped residual pressure or a pump that has already been modified.

Which part should you plan for?

Plan for the correct mechanical seal kit, including the associated O-ring. The available repair resources specifically cover mechanical seal and O-ring replacement on the relevant Lowara e-SV products.

Do not order on the words “3SV” alone. Use the full pump nameplate and, where possible, ask the supplier to confirm the kit against the serial number. If the pump is handling salt water, brine or operating in a desalination-related installation, state the pumped liquid and service conditions when sourcing the kit. The correct seal depends on the pump’s actual configuration, not just the model family.

“Balanced seal” does not mean “adjustable seal”

The term balanced mechanical seal can be misleading if you are reading service material quickly. In the supplied Lowara e-SVI source, the phrase refers to a balanced mechanical seal that is being replaced on an immersible multistage e-SVI pump.

That e-SVI source is not the same as a 3SV repair document, but it helps clarify the language: “balanced” describes the type of mechanical seal. It is not, by itself, an instruction to tighten the seal or evidence that a leak-adjustment screw exists.

What the documented repair approach implies

For the small Lowara e-SV pumps covered by the cited resources, mechanical seal and O-ring replacement is performed by removing the motor. The exact sequence should come from the manual for your pump, but the job generally follows this logic:

• electrically and hydraulically isolate the pump;
• relieve pressure and drain as required;
• mark or photograph the assembly before dismantling;
• remove the motor to access the seal area, consistent with the documented small e-SV repair approach;
• remove the old seal without damaging the shaft, sleeve or seating faces;
• install the new mechanical seal and O-ring in the correct orientation;
• reassemble, prime, vent air and test gradually.

If the shaft, sleeve or seal seats are scored, corroded or worn, a new seal alone may not hold for long. In that case, inspection of the surrounding parts is just as important as replacing the kit.

When to call a pump technician

Use a qualified pump technician if the pump is under warranty, if you cannot depressurise the installation safely, if the leak is heavy, if the pump vibrates, if the shaft or sleeve appears damaged, or if you cannot identify the exact seal kit.

The bottom line: for a Lowara 3SV/e-SV leaking at the mechanical seal, the available sources point to replacing the mechanical seal and O-ring with the correct kit. They do not describe stopping the leak by tightening or adjusting the seal. Confirm the model, verify the leak location, make the installation safe, and replace the sealing assembly properly.