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Do not operate or work on this engine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact any Caterpillar dealer for replacement manuals. Proper care is your responsibility. |
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Keep hands clear of fan and belts while engine is running. |
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Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts. When working on an engine that is running, avoid contact with hot parts and rotating parts. |
Compare the inlet manifold pressure to the pressure given in the TMI
The efficiency of an engine can be checked by comparing the pressure in the inlet manifold with the information given in the Technical Marketing Information (TMI). This inlet manifold pressure test is used when there is a decrease of horsepower from the engine, with no sign of a problem with the engine.
The correct pressure for the inlet manifold is listed in the TMI. The correct pressure is also on the Fuel Setting and the related Service Information System. Development of this information is performed under the following conditions:
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99 kPa (29.7 in Hg) dry barometric pressure -
29 °C (85 °F) outside air temperature - 35 API rated fuel
On a turbocharged, aftercooled engine, a change in the fuel rating will change the horsepower. A change in the fuel rating will change the inlet manifold pressure. If the fuel is rated above 35 API, the inlet manifold pressure can be less than the pressure given in the TMI. The pressure will also be less than the pressure that is listed on the Fuel Setting and the Related Service Information System. If the fuel is rated below 35 API, the inlet manifold pressure can be more than the pressure listed in the TMI. The pressure will also be more than the pressure that is listed on the Fuel Setting and the Related Service Information System.
| Required Tools | ||
| Part Number | Part Name | Quantity |
| 1U-5470 or 198-4240 |
Engine Pressure Group or Digital Pressure Indicator Gp |
1 |
Refer to Special Instruction, SEHS8907, "Using the 1U-5470 Engine Pressure Group" for the instructions that are needed to use the 1U-5470 Engine Pressure Group. Refer to Operation Manual, NEHS0818, "Using the 198-4240 Digital Pressure Indicator" for the instructions that are needed to use the 198-4240 Digital Pressure Indicator.
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| Illustration 1 | g02571852 |
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Tooling (A) 198-4240 Digital Pressure Indicator Gp | |
| Most Recent Required Tools | ||||
|---|---|---|---|---|
| Tool | Item | Qty | Part No | Description |
| A | 198-4240 | Digital Pressure Indicator Gp | ||
| A1 | 1 | 198-4234 | Digital Indicator | |
| A2 | 1 | 198-4237 | Pressure Sensor Gp
(0 to 3,445 kPa (0 to 500 psi)) |
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| A2 | 1 | 198-4238(1) | Pressure Sensor Gp
(0 to 34,450 kPa (0 to 5,000 psi)) |
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| A2 | 1 | 198-4239 | Pressure Sensor Gp
(0 to 41,368 kPa (0 to 6,000 psi)) |
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| A2 | 1 | 251-9600(2) | Pressure Sensor Gp
(0 to 68,900 kPa (0 to 10,000 psi)) |
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| A3 | 1 | 198-4236 | Adapter Cable As | |
| (1) | This sensor must be purchased separately, and is not included in the 198-4240 Digital Pressure Indicator Gp |
| (2) | This sensor can only be used on large diameter pressure taps like 6V-3965 Fitting. |
Open or remove, if applicable, the appropriate covers to access the parts of the engine needed to complete this procedure.
Note: Ensure that the air inlet and the exhaust are not restricted when you are checking the inlet manifold pressure.
Use the following procedure in order to measure the inlet manifold pressure:
- Remove the plug from the air inlet elbow.
- Connect the 198-4240 Digital Pressure Indicator Gp to the air inlet elbow at the pressure test location.
- Record the value.
- Compare the value that was recorded in Step 3 to the pressure that is given in the TMI.