Laing DDC / D5 Pump Maintenance
If your Laing DDC or D5 pump is struggling to start, making unusual noises, or simply not shifting coolant the way it should, do not panic. It is extremely rare for these pumps to genuinely fail. In the vast majority of cases, some fairly straightforward maintenance will sort the problem out. So, before you consider a return, could a quick clean be all that is needed? Let’s find out.
A word of warning before we begin. Do not run your pump dry for more than 10 seconds at a time. Both DDC and D5 pumps rely on coolant for lubrication, and running them dry will cause permanent damage to the impeller and bearing.
Why Pumps Stop Working Properly
The most common cause is debris trapped around the impeller. If you have been using opaque or pastel coolant, particles can build up inside the pump housing over time.
Even with clear coolant, small amounts of flux residue, o-ring fragments, or other contaminants can find their way into the impeller chamber and prevent it from spinning freely. That is not a sign the pump is dead. It just means it needs a clean.
Disassembly
Start by removing the pump from your loop and disconnecting it from any pump top or reservoir.
Laing / Xylem DDC
Remove the four screws on the underside of the pump to separate it from the DDC top or reservoir housing. This is dead easy, but do keep the O-ring safe for reassembly. Below is the Motor taken out of it’s casing, you usually won’t need to do this but it’s also good to know how easy liquid can get into the motor if the O-ring isn’t put back in place.. This often happens so take note.
Laing / Xylem D5
Unscrew the large retaining ring on the rear of the pump to separate it from the D5 top or reservoir housing. It is worth noting that some after market reservoirs use a hold-down plate over the pump body instead. If yours does, remove that first. Again, keep the O-ring safe for reassembly. You’re less likely to kill the pump if it’s installed without an O-ring on the D5, but that’s not a reason to forget to install it properly!
Cleaning the Impeller
Remove the impeller from the pump housing and inspect it for debris, build-up, or damage. Clean it thoroughly using distilled or deionised water.
While the impeller is out, clean the inside of the housing as well, removing any visible residue. Once everything is clean, place a small amount of distilled water into the impeller housing and then refit the impeller. This small amount of water is important as it provides the lubrication needed for the next step.
Testing the Pump
With the small amount of water in the housing, power the pump on for no more than 10 seconds, then switch it off.
Repeat this on/off cycle several times over a few minutes, checking that the pump starts reliably each time. If the pump starts successfully every time, drain the water from the housing and reassemble the pump onto its top, making sure the O-ring is seated correctly in its groove.
Reassembly and Refilling
Once the pump is back together, reinstall it in your loop. If you drained your system to remove the pump, I would recommend flushing the rest of your loop with distilled water before refilling. It is also quite important that you use fresh coolant rather than reusing old fluid that was drained out. Old coolant can contain the very contaminants that caused the problem in the first place, so it is not worth the risk.
Still Having Problems?
If the pump still will not start reliably after cleaning, and you purchased it from us directly, get in touch. We can help you under warranty (within the warranty period) to repair or replace the unit.
For those who have followed the steps above, though, the fix is usually straightforward. A bit of debris around the impeller is by far the most common culprit, and a thorough clean is all that is needed in the vast majority of cases. I do feel it is worth reiterating that genuine pump failures are quite rare, so it is always worth trying a clean before writing the unit off.
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