Usage:
3608 ( 6MC ),
3612 ( 9RC ) Engines Equipped With Electric Starting Motors
Improved Clamping Of Electric Starting Motor
The clamping of the starter motors can be improved by modifying the caps in the starter motor mounting groups. By removing 2.0 mm (.08") from the clamping surface of both caps (see Illustrations 1 and 2), the clamping load on the starter motors will be increased. This will help prevent excessive motion of the starter motors in the mounting groups.
When the caps in the starter mounting groups are being modified, remove the starters to inspect the 6V3538 Dowels. See Illustrations 1 and 2. These dowels locate the starters in the mounts. Replace the dowels if any wear is observed.
Illustration 1. Dimension for modifying caps in 9Z5951 and 9Z5952 Starter Mounting Groups (Custom Option for 3608 Engines).
Illustration 2. Dimension for modifying caps in 5Z9555 Starter Mounting Group (Custom Option for 3612 Engines).
Improved Electric Starter Pinion Engagement
On 3612 Engines equipped with Custom Option dual electric starters, the electric start controls include a feedback signal. The feedback signal provides for automatic indexing of the starter pinion. This system requires that the start button be depressed for up to ten seconds to ensure the pinion is allowed to index and engage.
The flywheel ring gear should have 1P0808 Grease Cartridge applied to the teeth every 250 hours. This will help prevent excessive wear on the starter pinion and ring gear.
If excessive pinion wear is a problem, the 4W9927 Flywheel Ring Gear (has chamfers on both sides) can be replaced with a 9Y5535 Flywheel Ring Gear (has chamfer on one side only). The ring gear with the chamfer on one side only provides increased pinion engagement.
New Serviceable Components In Electric Starter Groups
The 9Z5951 and 9Z5952 Custom Option Electric Starter Groups used on 3608 Engines and the 5Z9555 Custom Option Electric Starter Group used on 3612 Engines have the serviceable components listed in the chart.
Weekly Maintenance Schedule
Apply a thin film of 1P0808 Grease Cartridge to flywheel ring gear. This will improve starter pinion meshing.
Examine starter batteries, check all cells (voltage level), acid level and acid density, tight fit of terminal screws. Check connecting cable for tight fit and damaged insulation. If necessary, recharge battery on-site.
Monthly Maintenance Schedule
Conduct maintenance work on alternator or charging system and possibly auxiliary starting oil pump as described under semi-annual maintenance requirements. After some experience has been gathered, the regular monthly maintenance intervals may be extended.
Semi-annual Maintenance Schedule
For this type of scheduled maintenance work, it is advantageous to remove the starter.
Carbon brushes must be checked for proper condition from time to time. After removing the brush cover, it is advisable to use a hook to lift the spring which presses the carbon brush against the commulator (do not bend spring sideways and do not lift more than necessary). After that, check whether the carbon brushes move easily in the brush holder.
The carbon brushes and the brush holder must be free of dust, oil and grease. If these components are dirty or stuck, they must be cleaned and dried with a clean cloth, slightly moistened with gasoline (do not use cleaning wool because it easily leaves behind fibers). Do not use emery paper, files or knives on the bright front surface of the brushes. Blow out brush holder with dry compressed air.
If a brush is broken, unsoldered, or worn to such an extent that the spring or the wire strands soldered in the brush is likely to touch the brush holder [minimum carbon length about 15 mm (.6")], it must be replaced. Use only BOSCH® carbon brushes. Make sure the spring does not hit the brush when inserting carbon brushes.
Brush replacement only makes sense if the commutator is still in perfect condition. In the interest of operational safety, we consider it to be advisable to subject the starter to a general overhaul once the brushes are worn down to 16 mm (.6").
Fill oil bore and commutator bearing with Bosch Oil Part No. 011V13.
Troubleshooting Information
In case of malfunctions, keep in mind that the causes may not necessarily be attributable to the starter itself, not even to the battery, the switches, leads and connections but for example may be attributable to problems with fuel supply or injection system. The following suggestions on correcting malfunctions are limited to the starter system area.
