LG LDF7774ST dishwasher: small center leak during wash cycle — how to locate source

Hi, I’m Mike, your home appliance troubleshooting expert—when does the water show up: during fill, while it’s washing/spraying, during the drain, or even when the dishwasher is off?

Does the puddle show up at the front center under the door, or more toward the right-rear area where the motor and hoses sit?

When it leaks, do you see foamy suds at the bottom of the door, and are you using detergent pods along with rinse aid?

After a cycle, is the inner door edge noticeably wet with a water trail down the center, or does it stay dry while the drip only appears from underneath the machine?

Thanks—that helps. Based on “middle of the wash” and the leak showing near the center, here are the most likely causes and whether they’re DIY‑friendly:

• Most likely, DIY‑friendly:
  • Lower door seal or tub gasket leaking at the bottom center. The rubber can flatten or tear and seep only while spraying.
  • Cracked bottom spray arm or loose spray‑arm cap causing a jet that shoots at the door seam and sneaks out the bottom.
• Likely, technician‑level:
  • Sump/diverter seal seep under the tub (the sump is the plastic base that holds the filter and pump; the diverter is the valve on it). These leak only during wash when pump pressure is high, and drips appear from underneath the machine, not the door area.
  • Circulation pump or clamp/hose at the sump weeping during spray.

What I’d do in your shoes:

• If the drip seems to start at the front lip/door area, it’s usually worth a DIY try: door gasket/lower door seal or the bottom spray arm are common and inexpensive.
• If it truly originates from the middle bottom under the unit, it’s typically the sump/diverter or pump area—best to have a tech handle it because the dishwasher must be pulled out and tilted, with electrical and sharp‑edge hazards.

Typical costs:

• Door gasket/lower door seal or spray arm: low parts cost; DIY time under an hour.
• Sump/diverter/pump leak: parts can be a few hundred plus labor; total commonly $300–500.

Safety note: If you do pull the unit, cut power at the breaker and shut off water to avoid shock and leaks; edges under dishwashers are sharp.

Want a quick guided check to tell door‑area vs. under‑unit leak (no disassembly), or step‑by‑step DIY for the door seal/spray arm?

Great—do you want the quick no‑disassembly leak‑source check first, or the DIY steps to replace the door gasket/spray arm?

Here’s a quick, no‑disassembly leak‑source check you can do safely:

Safety: Water will be hot and there may be steam—open the door slowly mid‑cycle and keep hands clear of the spray.

1. Prep the “towel test”

• Dry the floor.
• Lay a 2–3 inch wide strip of dry paper towel along the floor right at the front lip of the door (left to right).
• Slide a second strip 6–8 inches back under the machine using a ruler or spatula. If you can, slide a third strip a bit farther back.

2. Run and watch timing

• Start a Quick/Normal cycle.
• At 5–10 minutes you should be in the main wash (you’ll hear strong, steady spraying). Check which towel strip gets wet first.

3. Mid‑cycle pause check (during wash)

• Open the door just enough to pause, wait 5 seconds, then open fully.
• Look and feel along the inner door bottom edge and front tub lip for fresh water tracks, especially at the center.
• Spin the lower spray arm by hand and inspect it for hairline cracks, splits at the seams, or a loose center cap.

4. Drain check

• Close the door to resume; when it switches to drain (loud humming and water whoosh), recheck the towels. Note if new wetting happens only during drain.

How to read the results

• Front towel gets wet first and you see a fresh water trail on the inner door/lip: most likely lower door seal/tub gasket or a cracked/loose lower spray arm jetting at the door.
• Front towel stays dry but the deeper towel gets wet first (during wash): likely sump/diverter seal area or circulation pump weep underneath.
• Wetting shows up only during drain: likely drain hose/clamp at the sump area rather than the door.

Tell me which towel got wet first and whether you saw a water trail on the inner door, and I’ll advise next steps (DIY vs. call‑out) specific to your result.