1997/05/26 Caterpillar

D9R (7TL852-Up, 8BL1053-Up),
D10R (3KR1-Up) Track-Type Tractors;
768C (02X),
772B (64W),
776D (5ER) Off-Highway Tractors;
769C (01X),
771C (3BJ),
771D (6JR),
773B (63W),
773D (7ER),
777D (3PR) Off-Highway Trucks;
775B (7XJ),
775D (6KR) Quarry Trucks;
5110 (7GN) Excavators Powered By 3408, 3412, 3508, 3512 Engines

This article supersedes the previous:

Service Magazine; February 26, 1996; Page 4; "Service Manual And Service Kits Available For Engine Variable Speed Fan Clutch".

Service Magazine: April 1, 1996; Page 15; "Two Service Kits Are Available For The Fan Clutch In Machine Engines".

A Variable Speed Fan Drive is standard equipment on the D10R Track-Type Tractor and 5110 Excavator and optional equipment on the other machines listed in the subtitle. These machines are powered with:

* 3408 or 3412 engines with mechanical fuel injection or

* 3408E or 3412E engines with electronic controls and hydraulically actuated electronic unit injection (HEUI) fuel systems or

* 3508B or 3512B engines with electronic controls and electronic unit injection (EUI) fuel systems

The 6I-4427, 123-6968, and 136-7609 Variable Speed Fan Drive Groups can be found on the these machines. The purpose of the variable speed fan drive is to reduce fuel consumption by minimizing fan horsepower demand and to satisfy environmental noise regulations.

Service Publications

Service Manual, SENR8603, "Variable Speed Fan Drive", describes how the variable speed fan drive operates and provides disassembly and assembly information. The fabricated tools required to service these fan drives are shown in this service manual.

A Service Magazine; April 15, 1996; Page 1; "Engine Variable Speed Fan Clutch System Service Tips", provides some troubleshooting information on the fan drive 101-0329 Solenoid Valve Assembly (pressure regulating valve).

Serviceability

The 6I-4427 and 123-6968 Fan Drive Groups are serviced with the same seal kit and overhaul kit. The 123-6968 Fan Drive Group incorporates a fan speed sensor while the 6I4427 Fan Drive Group does not. The speed sensor is used on engines equipped with an Electronic Control Module (ECM). The 123-6968 Fan Drive Group or the 136-7609 (preferred choice) Fan Drive Group can be used as a replacement for the 6I-4427 Fan Drive Group. If this substitution is made, the speed sensor remains disconnected, and the fan drive will operate properly. The 136-7609 Fan Drive Group can be used to replace the 123-6968 Fan Drive Group on D10R Tractors ONLY. Validation work, to ensure proper operation of the 136-7609 Fan Drive Group, has not been completed for the other applications.

An experienced service technician, using the recommended tools, can rebuild the above fan drive groups in approximately two hours. The first attempt at rebuilding a fan drive group may require as much as four hours to complete. The rebuilding time does not include the fan drive removal and installation time.

Installation

When installing a 123-6968 or 136-7609 Fan Drive Group on a D10R Tractor, make sure the 125-5035 Orifice Plug (Allen head) is NOT installed inside the control port supplying oil to the clutch piston. The control port is located inside the fan drive group 4-bolt mounting flange, on the right side of the machine. If the orifice plug is installed in the control port of the fan drive group on a D10R Tractor, the oil flow restriction will shorten the service life of the clutch in the fan drive group. The 125-5035 Orifice Plug is used in all the other machine applications. The control port is located inside the fan drive group 4-bolt mounting flange, on the right side of the machine for D10R, D9R Tractors, and 5110 Excavators. The control port is located on the left side of the machine on all off-highway trucks, off-highway tractors, and quarry trucks.

On D10R (3KR1-614) Tractors operating in cold ambient conditions, it is possible for an oil leak to develop past the fan drive low pressure shaft seals. Reducing the fan drive case pressure with a less restrictive drain line configuration can solve this problem. To install this less restrictive drain line configuration, a 135-9880 Engine Front Cover, a 6V-8642 Connector, and a 6V-4589 O-Ring Seal are required. The new engine front cover has a larger drain opening. The drain tube remains unchanged.

Less restrictive drain lines and fittings are also being used on 3400 powered off-highway trucks. This procedure has been previously published in "FIND"-TEXT.

Variable Speed Fan Drive Usage

Chart A identifies which fan drive groups, overhaul kit, and seal kits are used on which machines. Chart B and the illustration identify the components in the 121-5756 Seal Kit. Chart C and the illustration identify the components in the 121-5756 Overhaul Kit. Chart D and the illustration identify the components in the 141-9853 Seal Kit. Chart E and the illustration identify the components in the 141-9854 Overhaul Kit.

NOTE: The 6I-4427 and 123-6968 Fan Drive Groups use the same 121-5756 Seal Kit and 121-5767 Overhaul Kit. The 123-6968 and 136-7609 Fan Drive Groups use the same 119-4166 Fan Speed Sensor Group.

Identification of fan drive group seal kit and overhaul kit components.

Troubleshooting

When using the service tool (ET or ECAP) to troubleshoot the 123-6968 or 136-7609 Fan Drive Groups, DO NOT leave the fan in the Fan Override Mode (maximum fan speed) permanently since the fan drive clutch bearings may be damaged.