HOSE AS 4696168 - Caterpillar

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) 702 °C (1295 °F)
“B” 700 °C (1292 °F) 728 °C (1342 °F)
“C”
“D” 725 °C (1337 °F) 756 °C (1392 °F)
(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 because of the constant flow of exhaust gas past the thermocouple. For engines with dry exhaust manifolds, the exhaust port temperatures are 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 be different. The difference may vary by 38°C to 52°C or 68°F to 94°F.Be alert if an exhaust port temperature varies by more than 50 °C or 90 °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 if an exhaust port temperature varies by more than 100 °C or 180 °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.
To help prevent engine damage, never exceed the high idle rpm. An overspeed can result in serious damage to the engine. The engine can be operated at high idle without damage, but the engine should never be allowed to exceed the high idle rpm.
Tachometer - The tachometer displays the engine rpm. The high idle rpm and the rated rpm are printed on the engine Information Plate.
Hour meter - This meter indicates the total number of hours of operation of the engine.
Inlet air restriction (air cleaner differential pressure) - This gauge indicates the difference in air pressure between the inlet side and the engine side of the air filter element. The differential pressure for the air cleaner is measured from the air inlet for the turbocharger. The "LH/RH" switch on the instrument