Mechanical Gas Fuel System G5.9, G8.3, G855 – Master Repair Manual 013-046   Ignition Coupling

Preparatory Steps

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 WARNING 

Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

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Remove

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1) Bar the engine until the timing indicator on the front of the engine is at the prescribed ignition timing value. Check the alignment of the indicator on the rear of the ignition generator. The marks should be near alignment on the
clockwise (CW) mark. If the marks are approximately 180 degrees out of alignment, rotate the engine an additional 360 degrees and check the rear alignment of the ignition again.

2) Disconnect the wiring harness. Remove the two mounting capscrews on the ignition generator. Remove the generator and discard the gasket.

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Procedure for the oldham assembly.

Drive the spring pin (A) out of the coupling (B) and shaft (C).

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Remove the ignition coupling (B) from the shaft (C).

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Procedure for the ignition with spline coupling.

Remove the splined coupling and inspect it for wear. Discard if wear is found.

Manually check if there is any hub-to-shaft play and check if the set screw is tight. If no play is found, and the set screw is tight, proceed to installation of the spline coupling and ignition generator.

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Remove the retaining ring (1) on the accessory drive shaft (2).

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Loosen the set capscrew (3) in the rear rim of the splined coupling hub (1) with a 7/16 inch 12 point box end wrench. Inspect for wear on the inner surface of the spline hub (1) and for any wear on the key (2). If any sign of wear is found on either piece, discard both.

NOTE: If an oil leak is not present, skip to Assembly process.

Remove the retaining ring (4).

Drain the oil from the governor housing.

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Remove the four mounting capscrews (1) on the ignition timer support. Install two bolts into the ignition timer support (3) removal points (2). This will allow for the ignition timer support and the square key (4) to be removed from the governor housing. Discard the gasket and replace the square key if necessary.

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Disassemble

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Remove the retaining ring (1) from the rear of the ignition timer support. This will allow for the bearing (2) and bearing support (3) to be removed.

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Remove the oil seal in the ignition timer support.

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Inspect for Reuse

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Procedure for the oldham assembly.

Inspect the ignition coupling for cracks, deformities, or any other damage. Pay special attention to the coupling teeth (D), as well as the spring pin bore area (E).

Replace all worn or damaged couplings and spring pins.

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Inspect the intermediate coupling for cracks, deformities, or other damage.

Pay special attention to the slots (2 and 3) on either side of the intermediate coupling.

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Replace all worn or damaged couplings.

 
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Assemble

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On the accessory drive shaft, remove the two o-ring seals. Lubricate and install the two new o-rings.

Install a new oil seal in the ignition timer support

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Install the bearing (2) and bearing support (3) into the ignition timer support. Install the retaining ring (1) into the ignition timer support.

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Install

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Install the ignition timer support (3) with a new gasket onto the accessory drive shaft. Install the square key (4) into the keyway. Tighten the mounting capscrew (1).

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Procedure for the oldham assembly.

Install the coupling and the intermediate coupling in the drive shaft.

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Install the ignition drive coupling (B) on shaft (C), lining up the holes in the coupling and shaft.

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Drive the spring (A) through the coupling (B) and the shaft (C) until it is flush with the coupling outside diameter.

Fill the governor housing with oil to the recommended level on the dipstick. Refer to Procedure
015-006 in Section 6 of the GTA28 Operation and Maintenance Manual, Bulletin 4021558.

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Procedure for the spline coupling.

Wipe accessory drive shaft and keyway with a clean, lint free cloth.

Install the retaining ring.

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Insert the key into the keyway on the accessory drive shaft. Slide the key back onto the shaft until it is firmly seated in the keyway against the snap ring.

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Procedure for the spline coupling.

Apply Loctite™ 242 Thread locker to the capscrew threads.

Insert the capscrew into the tapped hole on the hub, making sure the capscrew does
not obstruct the keyway opening.

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Install the hub on the accessory drive shaft and slide it back until it makes contact with the snap ring.

Hand tighten the capscrew.

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Tighten the capscrew with a 7/16 inch 12 point box end wrench.

Place the wrench on the capscrew with the handle as close to the housing as possible. The illustration shows the capscrew at the 12 o’clock position. Rotate the wrench from position 1 to position 2 (at the opposite end of the housing), as illustrated.

NOTE: Overtightening the set screw may cause the hub to crack.

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Install the retaining ring (1) on the accessory drive shaft (2).

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Fill the governor housing with oil to the recommended level on the dipstick.

Install the splined coupling onto the splined coupling hub.

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Static Timing Check – with the engine barred so that the Number 1 cylinder is at the desired firing point on the compression stroke.

Align the timing mark on the back cover shaft with the stationary rotation mark
clockwise (CW) on the back cover.

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Install the new gasket onto the ignition generator.

Use the two mounting capscrews and install the ignition generator on the engine, keeping the two red lines on the back of the unit aligned as closely as possible.

If the two lines do
not meet, loosen the back cover by removing the four fastening screws and carefully tilting the top of the cover away from the unit, keeping the internal plug connected. Rotate the distributor shaft until the marks are aligned. Install the cover and securely tighten the four fastening screws.

Tighten the mounting capscrews and connect the wiring harness.

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Finishing Steps

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 WARNING 

Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.
  • Connect the battery cables. Refer to Procedure
    013-009 in Section 13.
  • Start the engine and verify the exhaust oxygen content is at 6.0 percent and the timing is at the correct specification. Refer to Procedure

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Last Modified:  29-May-2009