Hydro-Gear EZT (ZT-2200): Specs, Oil, Life Expectancy & Replacement

Short version: the EZT, Hydro-Gear model ZT-2200, is Hydro-Gear's most popular residential integrated transaxle: a 10 cc pump and 10 cc motor, up to 215 lb-ft of output torque and 7 mph, for mowers up to 900 lb. It's factory filled and sealed with an internal filter, and Hydro-Gear's manual says it doesn't need oil maintenance. Hydro-Gear doesn't publish a life expectancy. To replace one, order by the full model number on its label (it starts ZA, ZB, ZC or ZD) and tell us which side it's on.

EZT (ZT-2200) specifications

Spec	EZT (ZT-2200)
Application	Residential
Model number prefixes	ZA, ZB, ZC, ZD (ZF is the ZT-2100)
Pump	Variable, 10 cc/rev (0.61 in³) maximum
Motor	Fixed, 10 cc/rev
Input speed	3000 rpm maximum (hi-idle, no load); 1800 rpm minimum (loaded)
Output torque	Up to 215 lb-ft (291 Nm), per Hydro-Gear's product page
Speed	Up to 7 mph
Machine weight (gross)	Up to 900 lb (406 kg)
Axle	1.0 in, double-D or 4-bolt flange
Overall reduction	19.2:1 or 21.2:1
Brake	External cog brake standard, external friction brake optional (the manual lists cog or disc, inboard or outboard)
Filter	Internal mesh filter; all return oil passes through it
Oil	20W-50 engine oil
Oil capacity	56 fl oz / 1.75 qt (1650 ml); ZT-2100: 54 fl oz (1597 ml)
Unit weight	29 lb (13 kg)

Older EZTs carried Hydro-Gear number 310-2200. Toro's service manual lists that unit on the TimeCutter Z (2003–2006) and Precision Z (2005–2006).

Oil: sealed, with one exception

• Hydro-Gear's manual says the EZT "is factory filled, sealed and does not require oil maintenance." Add or change oil only if it's contaminated or has degraded.
• Drain plug: only ZT-2200 units with an E or F as the 3rd character of the model number (ZC-E…, ZC-F…) have one. Newer units, per Hydro-Gear's product page, are "serviceable with optional drain ports for easier oil changes."
• Drain only below 100 F. The internal expansion cavity can lead to overfill if you drain and refill hot.
• Correct level: 0.75–1.50 in (19–38 mm) below the top of the fill port, checked with the unit at 50–100 F. Recheck after about a minute of running.
• Oil: 20W-50 engine oil (minimum 9.0 cSt at 230 F / 110 C, API SL).
• Filter: internal. Hydro-Gear gives no service part number; the manual's parts list shows it only as "KIT, FILTER."

Signs of air or low oil, and the fix

Hydro-Gear's manual lists three symptoms of air in the system: noisy operation, lack of power after a short time running, and high operating temperature. The fix is to check the oil level and purge:

1. Check the oil level (above) and release the parking brake. Ideally, raise the drive wheels off the ground.
2. With the bypass open and the engine running, slowly move the control lever forward and reverse 5–6 times.
3. With the bypass closed and the engine running, do the same 5–6 times. Stop the engine, check the oil level and top up.
4. Repeat until the unit runs at normal noise and moves smoothly forward and reverse at normal speed. Then repeat under normal operating conditions.

Purge any time the system has been opened, oil has been added or changed, or a replacement EZT has been installed. Full details, including how to use the bypass to push the mower: how to purge a Hydro-Gear transaxle.

Repair or replace? Our practical advice

This section is RFQQQ's general guidance, not Hydro-Gear's.

Before condemning the transaxle, check the simple things: the oil level, that the bypass is fully closed, and the drive belt. Then purge it properly. If an EZT is still noisy, weak or running hot after that, the problem is likely internal. On a residential mower, replacing the complete transaxle is often the practical answer: a rebuild means removing the unit and opening a sealed case, and parts plus shop time can come close to the price of a new, factory-filled unit. If you or your shop prefer to rebuild, see our Hydro-Gear repair and seal kits and use the parts list in Hydro-Gear's EZT service manual.

How long does a Hydro-Gear EZT last?

Hydro-Gear doesn't publish a life expectancy or hour rating for the ZT-2200, and we won't make one up. Service life varies a lot with how the mower is used. In our view, the factors that matter most are:

• Load. The EZT is rated for machines up to 900 lb gross. A mower that runs near that limit, works hills or carries extra weight asks more of it.
• Use. The EZT is a residential unit. Hydro-Gear notes that commercial units have upgraded components, such as axles and bearings, for daily heavy use, so an EZT on a mower used commercially is likely to wear sooner.
• Oil condition. High operating temperature is one of the signs of air in the system. Low oil, air or contaminated oil can shorten its life, which is why the purge procedure matters after any service.
• The right unit. Hydro-Gear strongly discourages fitting a model the mower maker didn't specify.

Ordering the right replacement EZT

1. Read the full model number on the label, e.g. ZC-DUBB-4MDC-3PPA. Every character matters; units with the same ZC prefix can be built differently for different mowers. See how to find your Hydro-Gear part number.
2. Note the side: left or right as you sit in the seat. Left and right units can carry different model numbers.
3. Add the mower maker's part number if the label shows one, plus your mower's brand, model and serial.
4. Older 310-2200 label? Send it with the mower model and serial and we'll check what's available.
5. After installing, purge the new unit as above.

Shop EZT (ZT-2200) transaxles and parts or send us your numbers through the Hydro-Gear part finder.

Frequently asked questions

Sources: Hydro-Gear ZT-2200 product page, Cross Reference Guide, FAQ; BLN-52622 ZT-2100/ZT-2200 service and repair manual (2023); Toro-hosted copy of BLN-52622 (2013); Toro TimeCutter Z / Precision Z service manual.

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