- Generator Set:
- C175-16 (S/N: WYB1-UP)
Introduction
Note: Do not perform any procedure in this Special Instruction until you read and understand the information.
This Special Instruction addresses an issue related to moisture entry into the internal components of the electronic thermostat.
The first section of the procedure provides information that guides the technician through disassembly and inspection of the unit.
The next section details component replacement, installation, and installing a drain port in the motor cover that will allow drainage of internal moisture accumulation.
The final section provides procedural information related to sealing the unit from external moisture.
Read and follow these instructions carefully.
Required Parts
| Required Parts | |
| Qty | Part Number |
| 1 | 1P-4278 Hose Clamp |
| 1 | 2Y-5829 Nut |
| 2 | 3E-4353 Hard Washers |
| 1 | 5P-9770 Hose (525 mm) |
| 1 | 6V-4248 Bolt |
| 1 | 8T-4121 Hard Washer (if needed) |
| 1 | 8T-4196 Bolt |
| 1 | 9S-9332 Elbow Fitting |
| 1 | 9X-8243 Heat Shrink Tube (60 mm) |
| 1 | 118-8706 O-Ring Seal |
| 1 | 125-8797 Clip |
| 1 | 312-2189 Gasket |
| 1 | 312-2197 Motor Mount As (if needed) |
| 1 | 372-4980 Bracket |
| 1 | 383-8593 Electric Motor Gp (THERMOSTAT) (if needed) |
| 1 | Loctite 5900 RTV gasket material |
Inspection of the Electronic Thermostat
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| Illustration 1 | g02718645 |
Component breakdown for inspection of the electronic thermostat for moisture entry (1) Motor cover (2) Control module (3) Motor group (4) Motor mount assembly | |
- Remove the four bolts from motor cover (1). Remove the cover from the motor group.
- Disconnect the connector from control module (2). Remove the mounting bolts, washers, and spacers from the control module. Remove the control module from the electronic thermostat.
- Remove the four bolts and washers from motor (3). Remove the motor from motor mount assembly (4) .
- Visually inspect the motor housing for moisture entry, corrosion, and rust. Turn the armature of the motor to ensure that the motor turns freely.
If moisture entry, corrosion, or rust is found inside the motor housing, or if the motor does not turn freely, replace the motor. Obtain a new 383-8593 Electric Motor Gp , but do not install the motor group. Continue with this procedure.
If the motor is found to be dry and in good repair, continue with this procedure.
- Thoroughly inspect cavity (A) of the motor mount assembly for evidence of moisture entry, corrosion, and rust.
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| Illustration 2 | g02718782 |
Motor mount cavity area and correct drive pin alignment (5) Drive pin (A) Motor mount cavity area | |
- Also, inspect the alignment of drive pin (5) that is pressed into the end of the lead screw for the 3-way valve. The pin must be centered across the shaft of the lead screw.
If moisture entry, corrosion, or rust is found in the cavity of the motor mount, replace the motor. Obtain a new 383-8593 Electric Motor Gp , but do not install the motor group. Continue with this procedure.
If the drive pin is found to be out of alignment, replace the motor mount assembly. Proceed to ""Replacement of the Motor Mount Assembly" " for instruction.
If the drive pin of the motor mount assembly is aligned and in good repair, proceed to ""Install a Drain Fitting in the Motor Cover" ".
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| Illustration 3 | g02718837 |
Incorrect drive pin alignment | |
Replacement of the Motor Mount Assembly
Note: Only replace the motor mount assembly if the drive pin in the end of the lead screw has slipped and is not in proper alignment.
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Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure. |
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Before proceeding with this procedure, drain the engine cooling system to level that is below the level of the thermostat. when you remove the motor mount assembly from the 3-way valve, coolant will be allowed to drain from the valve opening.
| NOTICE |
|---|
Dispose of used engine coolant properly or recycle. Various methods have been proposed to reclaim used coolant for reuse in engine cooling systems. The full distillation procedure is the only method acceptable by Caterpillar to reclaim the used coolant. |
Remove the Motor Mount Assembly
- Use an allen head wrench to remove bolts (6) .
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| Illustration 4 | g02719561 |
Component breakdown for removal of the motor mount assembly (6) Bolts (7) Motor mount assembly (8) Lead screw (9) Gasket (motor group) (10) O-ring seal (B) Counterclockwise rotation to remove the lead screw from the piston | |
- Pull motor mount assembly (7) from the valve body. As you pull the motor mount assembly away from the valve body, you will be repositioning the piston inside the valve body. Continue pulling the mount from the valve until enough of lead screw (8) becomes exposed that you can begin turning the lead screw by hand.
- Completely remove the lead screw from the valve piston by rotating the lead screw in the counterclockwise direction (B).
- Remove the gasket (9) for the motor group and O-ring seal (10) .
Install the New Motor Mount Assembly, Motor, and Control Module
- Before attempting to install the motor mount assembly, remove the bypass tube from the valve body. The opening for the bypass tube will allow the access necessary to thread the lead screw into the valve piston during assembly.
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| Illustration 5 | g02719766 |
Assembly of the lead screw into the valve piston and shaft bearing (8) Lead screw (11) Valve piston (12) Shaft bearing | |
- Install the new motor mount assembly onto the valve body by first threading lead screw (8) into the center of valve piston (11). Rotate the shaft of the lead screw in the clockwise direction while threading the lead screw into the center of the valve piston.
- Install a new 118-8706 O-Ring Seal into the groove of the valve body.
- Ensure that the end of the lead screw is fully inserted into shaft bearing (12) before bolting the motor mount assembly to the valve body.
- Install the four allen head bolts for the motor mount assembly. Torque the bolts to the standard torque.
- Remove the old gasket for the motor from the mating surface of the motor mount assembly. Ensure that the mating surface is clean and dry.
- Install a new 312-2189 Gasket (9) for the motor group onto the motor mount assembly. Install the motor, bolts, and washers. Torque the bolts to standard torque.
- Install control module (2) to the valve body assembly. Ensure that you attach the ground strap to the proper location. Failure of the control module may occur if the module is not grounded properly.
Install a Drain Fitting in the Motor Cover
Be certain that you install the drain fitting according to the orientation of the electronic thermostat while mounted on the engine. The drain port must be installed on the bottom of the motor cover. The cover orientation is fixed, ensure that the correct orientation is determined prior to beginning this procedure.
- Use a "C" size (6.14680 mm (0.242 inch)) drill bit to drill a hole in the center of the bottom of the motor cover.
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| Illustration 6 | g02719965 |
Typical location for the drain fitting | |
- Use a 1/16 - 27 thread tap to tap the hole for the drain fitting.
- Install a 9S-9332 Elbow Fitting into the newly tapped hole.
- Apply a bead of Loctite 5900 along the sealing surface of the motor cover and the mating surface of the motor housing.
- Install the motor cover onto the valve assembly. Torque the bolts for the motor cover to the standard torque.
- Install the drain hose as shown in illustration 7.
- Install 525 mm (21 inch) of hose (15) to elbow fitting (13) that was previously installed in the bottom of the motor cover.
- Use hose clamp (14) to secure the hose to the fitting.
- Remove the bottom bolt from cover (16). Remove the bolt and washer. Leave the existing ladder clip in place.
- In the following order, install bracket (22) and the washer that was previously removed over the ladder clip. Install the new 8T-4196 Bolt (21) into the vacant bolt hole. Torque the bolt to the standard torque. Ensure that the orientation of the bracket is at a right angle to the cover.
- Use bolt (18), nut (19), and two hard washers (20) to secure clip (17) to the previously installed bracket. Thread the hose through the clip as shown in the above Illustration. Torque the nut to the standard torque.
Ensure that the hose is not taut between the fitting and clip. A subtle radius in the hose between the fitting and the clip ensures that the hose will not pull away from the fitting during operation.
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| Illustration 7 | g02721029 |
Routing of the drain hose for the motor cover drain (front side engine view) (13) 9S-9332 Elbow Fitting (14) 1P-4278 Hose Clamp (15) 5P-9770 Hose (16) Cover (17) 125-8797 Clip (18) 6V-4248 Bolt (19) 2Y-5829 Nut (20) Two 3E-4353 Hard Washers (21) 8T-4196 Bolt (22) 372-4980 Bracket | |
Use Heat Shrink to Seal the Motor Control Harness Connector
- Obtain approximately 60 mm (2.4 inch) of 9X-8243 Heat Shrink Tube for this procedure.
- Remove connector (23) from the control module. Use a pair of diagonal cutters to cut the tie wrap that is securing the harness to the ladder clip.
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| Illustration 8 | g02721332 |
Connector for the control module (single harness configuration) (23) Motor control connector | |
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| Illustration 9 | g02722064 |
Connector for the control module (dual harness configuration) (23) Motor control connector | |
Note: Whether your application has a single harness or dual harness configuration for the motor control harnessing, the procedure for sealing the connectors is identical.
- Slide the piece of heat shrink tubing over the connector and onto the harness. Connect the harness connectors.
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| Illustration 10 | g02721378 |
Heat shrink tubing on the harness | |
- Slide the heat shrink tubing over the connectors at the control module.
Note: Ensure that the end of the tubing is pressed firmly against the housing of the control module on all sides before you proceed.
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| Illustration 11 | g02721503 |
Positioning the heat shrink tubing prior to heating | |
- Beginning at the control module end of the heat shrink tubing, heat the tubing around the connector. Apply the heat until the tubing completely seals the connectors. Be sure to heat the tubing from several directions in order to seal the connectors.
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| Illustration 12 | g02721394 |
First, seal the tubing around the connectors | |
- From the opposite end of the heat shrink tubing, begin to heat the tubing around the harness. Apply the heat until the tubing completely seals the harness and harness grommet. Be sure to heat the tubing from several directions in order to seal the connectors.
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| Illustration 13 | g02721544 |
Second, heat the end of the tubing before heating the center | |
- As the heat shrink tubing forms around harness, ensure that the ends of the tubing seals properly around the harness. Ensure that the glue from the inside of the tubing oozes from between the harness and the tubing.
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| Illustration 14 | g02721726 |
Glue seam oozing from between the harness and heat shrink tubing (single harness configuration) | |
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| Illustration 15 | g02722069 |
Glue seam oozing from between the harness and heat shrink tubing (dual harness configuration) | |
- Reinstall the ladder clip. Securely fasten the harness to the ladder clip with a new 7K-1181 Cable Strap . Cut the cable strap to length after the harness is secure.