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On a Loch dishwasher poor cleaning is nearly always the filter, the spray arms or the way the machine is loaded. All three are owner checks and none needs a tool. A wash pump is the last entry on the list, not the first.
What you observe
- Some items spotless, others untouched — Water is not reaching everywhere: a blocked spray arm, or loading that shields part of the rack.
- A uniform cloudy film on glassware — Chemistry rather than mechanics — detergent, rinse aid or water that is too cool.
- NEAR MISS — there is standing water in the base after the cycle — Then the machine is not draining, and the drainage page ranks those causes properly.
Causes in likelihood order
- Water that arrives too cool, or not enough of it — A dishwasher cleans with hot water and many machines take it hot from the supply rather than heating it themselves. A long cold run to the machine, a supply valve part closed, or a blocked inlet screen leaves the wash cool and weak. Top of the list on this one: the connection is temporary on this machine, which makes the supply the first thing to check rather than the last. Loch sells countertop and portable dishwashers that connect to a kitchen tap, so the inlet adapter and the drain hose are part of the machine as far as faults are concerned.
- How the machine is loaded — Water is sprayed, not poured: anything that shields another item stays dirty. Bowls nested together, a large tray across the lower rack, or items blocking the spray arm's path all produce exactly the patchy result people blame the machine for. Second here: it is free to test: run the same items loaded differently.
- The filter and the sump — Every modern dishwasher filters the water it recirculates. A filter that has not been cleaned passes debris back over the dishes, and one that is not seated correctly lets larger pieces into the pump. It is the single most neglected part of the machine. Third: it remains the commonest cause even where something else outranks it on this machine.
- Detergent, rinse aid and the programme chosen — Old detergent loses its strength, a dispenser blocked by a plate never opens, an empty rinse-aid reservoir leaves film on glass, and an eco or quick programme is not meant to shift baked-on food in the first place. Fourth in order: it is worth eliminating with one full-length cycle and fresh detergent.
Work through it in this order
- Run the hot tap at the sink until it is hot, then start the machine — A machine that cleans noticeably better after the line has been cleared of cold water was never faulty — it was being fed cold.
- Spin each spray arm by hand with the racks loaded — An arm that catches on a handle or a tray cannot cover the load, and that is a loading fault rather than a machine fault.
- Lift the filter out of the base of the tub and look at it — A filter matted with debris, or a sump with food standing in it, has answered the question before any other check is made.
The owner checks, step by step
- Clear the cold water from the line before each cycle and check the supply valve — Run the sink's hot tap until it runs hot, then start the machine. Check the inlet screen at the valve if the fill is slow.
About 10 min
- Reload with nothing blocking the arms and run the same items again — Leave space between items, face soiled surfaces towards the centre, and keep large flat items out of the arm's path.
About 15 min
- STOP before removing the lower panel or the pump cover — Live terminals and a heating element sit behind it. Naming the likely cause is the useful end of an owner check.
Safety, before the checks
Safety
Unplug the machine or switch off its breaker before removing a panel, and shut the water off at the valve under the sink before disturbing a connection. Let the machine cool before reaching into the tub — the element in the base holds heat well after the door is opened.
Where the owner's part ends
Call when the filter is clean, the arms spin freely and clear, the load is spaced and the water arrives hot — at that point the wash pump or the diverter is the fault, and both are behind a panel. Call sooner if the machine is also leaving standing water.
Close neighbours
What this page does not cover
Generalized information. This page covers Loch dishwashers as a class rather than one family or model line; where a family-specific page exists it is the better answer and is linked above. Not covered here: part numbers, component locations and figures that vary between families.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
