Installation Of Electric (Digital) Tachometer Groups{7462} Caterpillar

Installation Of Electric (Digital) Tachometer Groups{7462}

Usage:

3406 (90U, 91U),
3408 (67U, 99U),
3408 (67U),
3412 (60M, 38S),
D348 (36J, 38J),
D349 (61P, 62P),
D353 (46B, 47B),
G342 (71B),
3304 (2B, 4B, 37Y),
3306 (23C, 66D, 67D, 7Y),
D379 (68B, 69B),
D398 (66B, 67B),
D399 (35B, 91B),
G379 (72B),
G398 (73B),
G399 (49C),
3304 (5B),
3208 (75V, 1Z)

The electric (digital) tachometer groups above are replacements for the former groups or can be installed on engines without tachometer groups. For installation of the groups, see the instructions that follow.

Group Chart

(1) Fasten program board (1) in position on the back of electric tachometer (2) with two screws. See the above chart for the correct tachometer and program board for the number of flywheel ring gear teeth per revolution.

Tachometer Group Replacement

NOTE: The tachometer may be located on top of the instrument panel with a 7L4535 Mounting Group (as shown), in a premium panel, or installed remotely from the engine.

(1) Disconnect wires (3) from former tachometer (4). Remove the wiring. Remove two nuts (5) and bracket (6). Remove former tachometer (4) from the tachometer mounting bracket.

(2) When necessary, remove former sending unit (7) from the tachometer drive. Install 9B2232 Cap (8) and 1S7527 Gasket on the tachometer drive.

(3) Put electric tachometer (2) in position. Install bracket (9) and two nuts (10). Cut off the bare (without insulation) wire even with the cable jacket (cover) at the tachometer end of 6V2744 Wire. Install 9G3186 Terminals on 6V2744 Wire and connect the end of the wire with two terminals to the tachometer. Connect the end of the wire with three terminals to the terminal strip of the dual speed switch or the electric governor; see the Tachometer Wiring Diagram on Page 8.

NOTE: If a dual speed switch or an electric governor is not on the engine, install a 5N8757 Magnetic Pick-up Group. Use a 5N8802 Magnetic Pick-up Group for D348 and D349 engines, or use a 5N9076 Magnetic Pick-up for 3208 Engines.

(4) With the engine stopped, install magnetic pick-up (11), with locknut (12), either in the hole with the plug in flywheel housing (13) or in the hole in plate (14). Install the magnetic pick-up until the end comes in contact with teeth (15) on the flywheel ring gear.

NOTE: For all EXCEPT 3208 Engines, if there is no existing hole for the magnetic pick-up, drill a 14.50Ø (.570"Ø) hole through the flywheel housing in line with the flywheel ring gear teeth. Make 5/8"-18 threads in the hole. FOR 3208 ENGINES, REFER TO STEP 6.

(5) Loosen magnetic pick-up (11) 1/2 turn. This will give approximately 0.55 to 0.83 (0.022" to 0.033") clearance at location (A), between the end of the magnetic pick-up and the teeth on the flywheel ring gear. When clearance at location (A) is correct, tighten locknut (12) to a torque of 45.0 ± 7.0 N·m (35.0 ± 5.0).

NOTE: Beginning with 3208 Marine Engine Serial Number 1Z3500, the flywheel housing already has the hole. All that is needed for these engines is to remove a plug from the hole and install the magnetic pick-up according to the procedure given in step 7. For other flywheel housings, drill a hole according to the instructions beginning with step 6 that follows.

(6) For those 3208 Marine Engines that do not have hole (B) in the flywheel housing for installation of a magnetic pick-up, proceed as follows:

1 - If there is no existing hole for magnetic pick-up, use the dimensions shown to drill a hole 17.5Ø (.689"Ø) at location (B). Put a 38.1Ø (1.50"Ø) spot face around the outer diameter of hole (B).

2 - Use a thread tap to put 3/4"-16 threads all the way through hole (B).

(7) With the engine stopped, install magnetic pick-up (16) with locknut (17) in hole (B). With nut (17) loosened, turn magnetic pick-up (16) in until the end comes in contact with gear teeth (18) (on the flywheel ring gear). Now loosen magnetic pick-up (16) 1/3 ± 1/10 turn. Hold the magnetic pick-up in this position and tighten nut (17) to a torque of 45 ± 7 N·m (35 ± 5 lb ft). Clearance between the end of magnetic pick-up (16) and gear teeth (18) must be 0.30-0.75 (0.012"-0.030").

NOTE: Each 1/3 turn of the magnetic pick-up will result in an approximate change of 0.51 (.020") clearance from the flywheel gear teeth.

(8) Connect the wiring as shown in the wiring diagram on page 8.