it's leaving dark gray or black greasy streaks on my clothes, only on certain loads.

Diagnosis

The appearance of dark gray or black greasy streaks on your Maytag MVW7230HW is typically caused by a failure of the tub seal or a leak in the transmission gearcase. In this specific top-load model, the transmission contains a heavy-duty lubricant that is designed to stay contained within the lower housing. When the rubber seal between the transmission and the tub degrades or becomes brittle, this oil escapes and mixes with laundry lint and detergent residue, creating a thick, gray-black sludge that clings to fabrics. You will notice this happens "only on certain loads" because the oil often accumulates in the bottom of the outer tub or on the agitator fins during periods of inactivity. When you run a heavy load or a high-spin cycle, the agitation process whips this oil into the water, dispersing it across the clothes. To confirm this, take a clean white paper towel and wipe the underside of the agitator or the very bottom of the washer tub after a cycle; if you see a viscous, dark oil residue rather than just gray lint, your seal has failed.

How to Fix It

If the leakage is minor or caused by a buildup of "scrud" (detergent and softener residue mixing with trace oils), a deep chemical purge can sometimes resolve it. However, if the seal is physically breached, a mechanical replacement is required. Follow these steps to address the issue:

1. Chemical Flush: Set the washer to the "Clean Washer" cycle. Use a high-temperature setting and add 1 cup of liquid chlorine bleach or a specialized washing machine cleaner tablet (like Affresh). Run the cycle completely without clothes to strip surface oils from the drum.
2. Inspect the Agitator: Remove the agitator cap (if applicable) and check for excessive play. If the agitator wobbles significantly, the drive hub may be worn, allowing oil to migrate upward.
3. Seal Replacement: If streaks persist, you must replace the tub seal (Part #W11413311 or equivalent). Disconnect the power and water lines.
4. Drain and Disassemble: Drain the tub completely. Remove the top console and the drive belt. Unbolt the agitator and the pump assembly to gain access to the transmission housing.
5. Clean the Tub: Before installing the new seal, use a degreaser (like Simple Green) and a scrub brush to remove every trace of black grease from the inner and outer tub walls. If you leave old grease behind, it will contaminate the new load immediately.
6. Install and Test: Seat the new seal firmly using a rubber mallet, ensuring it is flush. Reassemble the unit and run two "Clean Washer" cycles before adding clothes.

If That Didn't Work

• Check the Drive Belt: Inspect the drive belt for "glazing" or fraying. As the belt wears down, it can shed small particles of black rubber and oil-based compounds that look like greasy streaks. If the belt is slipping or charred, replace it immediately to prevent the motor from overheating.
• Inspect the Suspension Rods: If the washer is unbalanced, the tub may be hitting the side of the cabinet, rubbing against the outer tub's grease points. Check the four suspension rods for spring tension; if one is collapsed, the tub will tilt and leak oil from the shaft.
• Address Detergent Overload: If you are using excessive amounts of liquid fabric softener or "pods" in a high-efficiency (HE) machine, a waxy buildup can form in the outer tub. This buildup traps oil and dirt, releasing it in streaks. Switch to a high-efficiency powder detergent for three loads to strip the wax.
• Replace the Transmission: If the seal replacement doesn't stop the leak, the internal gaskets of the transmission gearcase have likely failed. At this stage, replacing the entire transmission assembly is the only permanent solution.

Heads Up

• Avoid Fabric Softeners: Liquid softeners contribute heavily to the "sludge" that traps transmission oil. Use white vinegar in the softener dispenser to keep the tub cleaner.
• Load Balance: Always balance your loads. Overloading the MVW7230HW puts excessive lateral pressure on the tub seal, which accelerates the breakdown of the rubber and leads to leaks.
• Hot Water Use: Periodically run your sheets and towels on the "Hot" setting. This helps melt away accumulated oils and residues that cold water cannot dissolve.
• Warning: If you smell a strong "burnt rubber" or "chemical" odor along with the streaks, stop using the machine immediately to avoid damaging the motor.