SEAL-U-CUP 3673933 - Caterpillar

Exhaust temperature - This gauge indicates the exhaust temperature at the exhaust inlets to the turbochargers. The two exhaust temperatures may vary slightly. This may be due to variation of the sensitivity of the two thermocouples. The "LH/RH" switch on the instrument panel is used for toggling between the left side and the right side exhaust temperature.The exhaust temperatures at the exhaust inlets to the turbochargers provide a good indication of engine performance. For engines with dry exhaust manifolds, the temperatures are representative of the actual temperatures of the valves. Monitor this parameter frequently.Normal operating temperatures and extreme operating temperatures for different ratings are listed in Table 1. If the recommendations for the engine installation, the rating, and engine maintenance are followed, most engines will operate at the normal limit or below the normal limit.
Severe damage to the engine can result if the exhaust temperature at the inlet to the turbocharger exceeds the extreme limit.
Table 1
Temperature Limits for the Exhaust Inlet to the Turbocharger
Rating (1) Normal Limit Extreme Limit
“A” 650 °C (1202 °F) 692 °C (1278 °F)
“B” 677 °C (1251 °F) 718 °C (1324 °F)
“C”
“D” 704 °C (1300 °F) 746 °C (1375 °F)
“E”
(1) For the rating definitions, see this Operation and Maintenance Manual, "Engine Rating Definitions".Pyrometer - The pyrometer displays the temperature of the exhaust for the exhaust port of each individual cylinder.The exhaust port temperatures are a good indication of the condition of the cylinders. The displayed temperature is slightly lower than the actual temperature in the cylinder. This is because of the constant flow of exhaust gas past the thermocouple. For engines with dry exhaust manifolds, the exhaust port temperatures areusually lower than the temperatures at the inlet to the turbochargers.Guttering of valves can be diagnosed with the exhaust port temperature. The ability to diagnose this problem may help to prevent additional damage that could cause further downtime with a higher repair cost.During normal operation at rated load, the temperature of the hottest cylinder and the coldest cylinder may differ by 38 to 52 °C (100 to 125°F).Be alert if an exhaust port temperature varies by more than 50 °C (122 °F) from the average temperature of all of the cylinders.If a cylinder exhaust port temperature varies by more than 50 °C continue to monitor the cylinders temperature. At this point there is not a need to immediately troubleshoot the cylinder only monitor the cylinder to ensureit maintains temperature. During monitoring of the cylinder, if the temperature difference from the average increases close to 100 °C troubleshooting on that cylinder should begin. See the troubleshooting guides for exhaust temperatures and cylinder performance.Perform corrective measures immediately if an exhaust port temperature varies by more than 100 °C (212 °F) from the average temperature of all of the cylinders.The exhaust stack temperature is not a suitable substitute for the exhaust temperature at the inlet to the turbocharger. However, a comparison of the two temperatures can help to assess the performance of the turbocharger.
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