HOSE 4236378 - Caterpillar

CONFIDENTIAL TIBU3844
TECHNICAL INFORMATION BULLETIN May 7, 2003
Wheel Loaders
Wheel Tractors
Landfill Compactors 988G (S/N: 2TW1-Up, BNH1-Up)
834G (S/N: 6GZ1-Up, BPC1-Up)
836G (S/N: 7MZ1-Up, BRL1-Up)
Component Code(s) 1059, 1088SUBJECT: Troubleshooting Exhaust Gas Leaks That May Contribute to Excessive Engine Compartment Temperatures and Soot Accumulation
PROBLEM:
Exhaust gas leaks can elevate the air temperature in the engine compartment. Depending on the location of the leak, the exhaust gas can elevate temperatures in local areas and lead to component failures. Exhaust gas leakage can create an accumulation of soot on the interior of the engine compartment. If soot is visible, the exhaust system should be inspected to locate and repair any leaks.
SOLUTION:
Inspect all components and replace any components determined to be defective. Components found to have cracks may be contributing to excessive exhaust gas leakage and should be replaced. The following information may help to troubleshoot leaks found in the exhaust manifold gaskets and the muffler inlet joint.
Exhaust Manifold
Exhaust manifold gasket leaks at the joint with the engine head may contribute to localized overheating of adjacent "soft" components including seals, fittings, hoses and wiring. If a leak is discovered, replace the exhaust manifold gaskets as necessary. Refer to "Exhaust Manifold - Remove and Install", Disassembly and Assembly, 3406E & 3456 Engines for Caterpillar Built Machines, RENR1364 for information on replacing the gaskets.
Muffler Inlet
Under normal conditions, leakage from the joint connecting the turbocharger outlet pipe and muffler is minimal and should not contribute to compartment overheating or result in soot accumulation. If leakage is thought to be excessive, a problem may exist with the joint assembly or one of the components. Following is information on the joint components that may help reduce exhaust gas leakage:
Although all machines have been assembled with the 141-1480 Clamp, SIS has incorrectly called out the slightly larger 7E-6455 Clamp for earlier machines. The larger clamp may not adequately tighten the joint as the clamp band ends may contact each other. SIS documentation is being corrected. Neither clamp is marked with a Caterpillar part number but a number stamped on the inside of the band indicate the diameter. The stamped number on the 141-1480 Clamp should include "521" to represent a 5.21 inch diameter clamp.
Clamps not tightened to the proper torque may also contribute to exhaust gas leakage. The correct torque for the clamp as used on these mufflers is 55+/-10 N-m (41+/-7 lb-ft). During the torque procedure, the muffler inlet port will deform to fit tightly around the turbo outlet pipe. It is important to continue application of torque until the nut stops turning with the required torque applied. If the ends of the band on a properly tightened clamp contact each other, replace the clamp.
Incorrect location and orientation of the clamp may affect joint leakage. The clamp band must cover all slots or holes in the wall of the muffler inlet port. There is a hole in the muffler inlet port that is used to suspend the muffler assemblies with a hook during the painting process. This hole should be covered and effectively plugged