Volvo Penta SX-C SX-M Nedre gear

Full technical guide to the Volvo Penta SX-C and SX-M lower gear units: similarities and differences, key components, OEM part numbers, seals, bearings, anodes, and related replacement parts

The lower units of Volvo Penta SX-C and SX-M are technically identical, except for the following parts:

SX-S & SX-ST: The water supply tube 3852314 (№48 Right scheme) is attached to a “guide and seal” plate with reference 3853932 (№35 Right scheme)
Unlike the above drives, the rest use a box-shaped rubber seal, reference 3854595 (№22 Left scheme), attached to retainer 3854601 (№53 Left scheme).
Not all SX models have a trimming fin 3854402 (№38 Both schemes).

Although the water supply tubes are slightly different, the top seal 3852315 (№48 Left scheme) is identical for both units. From this line onward, our reference scheme will be the left one, unless otherwise stated.

On the front side of the lower unit, an anode is placed (№53). Reference 3855411 represents zinc, 3863193 aluminum, and 3855412 magnesium. If you also plan to replace the anode on the transom shield (Reference 3854130 represents zinc, 3586461 aluminum, and 3855610 magnesium), you may also consider buying an anode kit that includes both and all necessary installation hardware.

Recmar® Zinc Anode kit for Volvo Penta SX DP-SM 3855411 3854130
Recmar® Aluminum Anode kit for Volvo Penta SX DP-SM 3863193 3586461
Recmar® Magnesium Anode kit for Volvo Penta SX DP-SM 3855412 3855610

On the front side of the gear is located the O-ring between the upper and the lower gear unit, sealing the oil passage. Its reference is 3852959 and is depicted under №24 on the scheme. The splined sleeve 3852268 (№42) transfers the power from the upper gear unit to the vertical shaft of the lower gear unit. The bearing retainer keeps the bearings in place and is sealed with an O-ring 3852866 (№23).

Three bearings are located on the countershaft: 3854250 (№17), 3854249 (№16), and the pinion’s bearing 3853934 (№3). The nut 3851003 (№8) holds the pinion in place. It is recommended to replace it if you change the bearings.

On the horizontal shaft, usually called the propeller shaft, two bearings are in place. The roller bearing 3850942 (№8) is located on the gear, while number 3854249 (№10) is pressed inside the propeller housing.

The majority of the sealing components, like O-rings, sealing rings, and grommets, are included in the lower unit seal kit 3855275 (№56), yet a quick “propeller reseal” would include only the housing seal 3863090 (№11) and the O-ring 3852865 (№12). The gear oil drain plug O-ring 3855081 (№26) should also be replaced.

Right after the housing, a thrust washer 3852020 (№45) is located. After the propeller, another thrust washer is placed, and its reference is 3852350 (№44). Lastly, the propeller is held secured with a lock nut kit (№46) 3850984. It is a regular nut, with a “castle nut washer”, and a cotter pin that prevents any movement.

Frequently Asked Questions About Volvo Penta SX-C SX-M Lower Gear Unit Maintenance:

What is the oil capacity of Volvo Penta SX drives, and how often should it be changed?

All Volvo Penta SX drives need 2.1L of 75W90 synthetic oil. Change it every 100 hours, or every season.

How to drain the gear oil of an SX drive?

To drain the gear oil of a Volvo Penta SX drive, you need to follow these steps:

The outdrive must be set to its “TRIM DOWN” position.
Loosen the dipstick 3854847, which is located on the upper gear housing.

Place a 2.5L tray below the drive. Loosen the oil drain plug 3854539, located on the port side of the lower gear housing.

How to fill the SX drive with new gear oil?

Loosen the three bolts that secure the cover of the shift shaft mechanism on the upper gear unit, and then unscrew the oil level plug 3854539.

Connect a hand pump to add fresh 75W90 oil from the lower oil drain plug.

Pump oil until your oil level plug drips.

Use a level to make sure your drive is not inclined and is perfectly leveled to the ground. Use new O-ring seals: One 3852045 for the oil dipstick plug, and two 3855081 for the drip and the drain plugs. Clean the spilt oil, then install the cover.