Brand: LG Model Number: WM4270HVA Main Symptom: Mushroom Valve/Air vent - suds coming out of back of washer What happens & when: Sudsy water shoots out the vent towards the end of the cycle. I have tried less HE type soap. I also removed the mushroom valve and cleaned the valve and the white receptacle it sits in - both were covered in black (we have hard water in my area). The mushroom cap has a hole at the bottom, and I can imagine that the mold has also gotten into the pin hole too. My question: Should I replace the valve entirely? Also, is it supposed to “float” down when you put it back into the white receptacle - it just falls back in place; and doesn’t slowly sink back into place (found one video online about my problem and it looked like it should have some lift underneath). Another reason I think it might be a failing part or at least not efficient/effective.
Error Code (if any):
Parts or tests already tried:
Photos / video link:
For an LG WM4270HVA, the mushroom valve ( 4769ER4001B Float Assembly | Genuine Lg OEM In Stock ) (air vent/check valve on the rear tub vent assembly) should move freely, but it is not designed to be a slow-damping float. When you place it into the housing, it will generally drop back into position under its own weight. So the fact that it “just falls back in place” is not, by itself, a sign that it’s bad.
The more important issue is why sudsy water is being forced out of the vent:
Most common causes
Oversudsing (even with HE detergent)
Too much detergent.
Concentrated detergent doses not adjusted properly.
Residue buildup from years of detergent use causing recurring suds.
Restricted vent assembly
The mushroom valve, vent housing, or connected tubing can become partially clogged with detergent residue, mold, or hard-water deposits.
If air cannot move properly, water and suds can be pushed out.
Drainage issues
A partially restricted drain pump, drain filter, or drain hose can leave excess water in the tub and contribute to suds being forced into the vent near the end of the cycle.
Failed mushroom valve
If the rubber is swollen, distorted, hardened, cracked, or coated internally with buildup that cannot be cleaned, replacement is reasonable.
Should you replace the mushroom valve?
Given that:
It was heavily contaminated with black buildup,
You suspect the tiny vent opening may still be obstructed,
The part is relatively inexpensive,
Yes, replacing the mushroom valve is a reasonable next step. However, I would not assume it is the sole cause until the entire vent path is confirmed clear.
What I would check next
Run a Tub Clean cycle (or hottest empty cycle available) with a washer cleaner.
Verify the drain pump filter is clean.
Inspect the vent hose/tube connected to the vent assembly for buildup.
Use only 1–2 tablespoons of HE detergent for several loads to eliminate residual oversudsing as a factor.
Using a silicone lubricant on the shaft can help it slide smoothly
Replace the mushroom valve if the rubber shows any deterioration or if the pinhole cannot be fully cleaned.
One diagnostic clue
If the water coming out of the vent is very foamy/white suds, the problem is usually detergent-related or residue-related. If it is mostly water with little foam, I’d focus more on a vent restriction or drainage issue.
Can you tell me:
Does this happen on every load or only certain cycles?
Is the discharge mostly suds or mostly water?
Have you cleaned the drain pump filter recently?
Those answers will help narrow down whether the valve itself is the likely culprit.
Thanks for the response and the info - very helpful.
I didn’t include in my initial post that the connecting air hose was also filled with black residue. I cleaned it out too (only as far as I could reach). There is air coming thru the vent on a hot cycle (I can feel it with my hand), so it is working but maybe not optimally, I may just order both parts and see if that resolves the problem.
But, before I do that, what specific silicone lubricant do you recommended? Would a garage door-silicone type work (it is all I have on-hand, but the video online suggested an O-ring silicone lubricant)? Don’t want to cause any more issues. I may try, one more time, detaching the hose and cleaning it thoroughly and then try the mushroom valve (lubricant and cleaning the pin hole - with a pin, this time).
If all else fails, I’ll get both new parts (hose and valve) and replace them entirely. Trying to avoid that option since I just recently replaced an intake valve - had a solenoid failure there. .
As far as lubricants go I wouldn’t suggest the garage door stuff, I imagine its very thick. You want something that lubricates but doesnit leave residue
Follow-up: I ended up replacing the valve and the air hose (that was filled with gunk). But I am still getting a small amount of water pooling at the left back corner footer - when the hot water is selected. And occasionally when the load is full some soapy water still shoots out the back air valve release (thought the replacements would fix this - but it doesn’t happen every time but again with hot water). Anway, the LG washer is only 10 years old, so I don’t want to replace it just yet. Lastly, I did struggle with the hose clamp - between the location (under all the water intake hoses) and the hand strength required to fully open/close it - it got the best of me even with a vise grip. Do you think it matters if it is not perfectly aligned - the air does release out the back (so it is doing the job, but it doesn’t cover the air out-take tube completely maybe halfway?). Appreciate any suggestions.
Sorry I didn’t mention - that I did that too - but with a Tide product. Maybe I need to do it again. There was significant build up in the gasket, rim, etc. I had cleaned it by hand before but tried the Tide cleaner, this weekend. I’ll also check it for leaks. Thanks for all the back and forth - much appreciated.