Why does my washing machine still smell like a sewer after deep cleaning everything?

Since you've allready scrubbed the machine and cleared the pump, you're almost certainly looking at a plumbing issue behind the wall rather than a failure inside the drum. If the machine itself is spotless, the smell is likely sewer gas traveling up the drain line. You need to verify if there is actualy a P-trap installed in the wall behind that standpipe. If there isn't one, or if it's installed improperly, there’s nothing to stop those gases from venting directly into your laundry room and back into the machine's internal sump.

Another common culprit is how deep you've shoved the drain hose into the standpipe. If you pushed the hose too far down—like more than 5 or 6 inches—it can actually sit below the water level of the trap or create a siphon that pulls the protective water seal out of the trap after a cycle. Make sure you’re using the plastic U-shape bracket that came with the machine to keep the hose from sliding down too deep. There needs to be an air gap at the top of that pipe; if it's taped up airtight or shoved in deep, the gas has nowhere to go but up into your drum.

You shold also check for a clogged vent stack on your roof or a failing Air Admittance Valve (AAV) under a nearby sink. If the plumbing isn't venting correctly, the vacuum created when the washer drains will suck the water right out of the trap, leaving it dry. A dry trap is basially a highway for sewer smells. Pour a cup of water down the standpipe manually when the machine isn't running and see if the smell dissipates for a few minutes. If it does, your trap is definatly being sucked dry during the drain cycle.

And honestly, while 19 inches might be the minimum height in your manual, it is on the lower side for modern front-loaders. If the drainage isn't perfectly tuned, you can get a tiny bit of backflow that sits in the bottom of the outer tub where you can't see it. But focus on that P-trap first, becasue a clean machine shouldn't smell like a sewer unless it's literally breathing in sewer air.

Sounds like classic 'spider' rot. These front-loaders have an aluminum support arm behind the drum that traps hair and soap scum til it turns into a black sludge you can't reach. Back in the day, we'd run a 'boil wash' with real TSP or Borax once a month to keep that outer tub from becoming a swamp.

If you've been doing cold-only cycles with liquid softener, you've built a slime factory back there. Try a 90-degree cycle with a cup of dishwasher detergent—the old powder stuff. If that doesn't kick it, your spider arm is probly corroded and holding the stink.

You really ought to inspect the detergent dispenser housing assembly becuase the overhead water distribution jets frequently develop a bacterial biofilm on the ceiling of the compartment which remains entirely obscured unless the drawer is fully extracted. Furthermore, the bellows—specifically those secondary weep holes designed to facilitate drainage from the gasket folds—often become obstructed by calcified minerals and lint, creating an anaerobic environment for stagnant water to putrefy behind the rubber seal regardless of how shiny the stainless steel drum appears, essentially allowing the door's own sealing assembly to harbor the source of the stench you're experiencing.