Usage:
7211 And 7221 Marine Transmissions
Description of Change: A new control valve group is used in 7211 and 7221 Marine Transmissions.
The new control valve group uses a new basic control valve group that has a new relief valve assembly, a new load piston and two different springs. Also, hardened washers are used instead of lockwashers.
The new relief valve assembly has a 15° chamfer on the land which controls pressure, and the poppet has a larger diameter orifice in comparison to the orifice used in the former relief valve assembly.
The chamfer on the land and the larger orifice prevent neutral pulsations (rapid but small changes in pressure) that will not let the clutch engage smoothly when the transmission is put into gear.
The change in springs and the new piston cause a neutral pressure of 240 kPa (35 psi) which prevents a ratchet-type noise when the transmission is put into gear.
The result is smoother operation with less noise, when the transmission is put into gear.
Adaptable As: The new parts, used together, are direct replacements for the former parts as shown in the chart.
Procedure For Installation Of The New Parts
1. Remove the 5L7364 and 5L7296 Covers.
2. Remove the 4M7910 Piston, 5M6108 and 5M6112 Springs and the 3N4324 Valve Assembly.
3. Install the 3T2254 Valve Assembly with the existing 7M1397 Spacers, the 8M6402 and 8M6403 Springs and the 3T2255 Piston.
Location of the new parts and the covers.
4. Start the engine and warm up the transmission oil. At low idle rpm with the marine gear control in either the "ahead" (forward) or "astern" (reverse) position, the clutch pressure must be 1740 ± 50 kPa (253 ± 7.5 psi). This will give 240 kPa (35 psi) at low idle rpm with the marine transmission in the "neutral" position.
Adjust the in-gear pressures with 7M1397 Shims to give the correct pressure.
NOTE: If the pressure in the "neutral" position is more than 280 kPa (40 psi) and there is a ratchet noise when the transmission is engaged, remove shims to decrease the pressure.
If the pressure takes more than five seconds to increase in the "ahead" or "astern" position, check the neutral pressure. If necessary, increase the neutral pressure to 240 to 280 kPa (35 to 40 psi) by the addition of shims.