Heat Shield Modification Can Extend the Life of the Center Valve Cover Seal [TIBU3843]

AIR INLET AND EXHAUST SYSTEM

EXHAUST GP

Heat Shield Modification Can Extend the Life of the Center Valve Cover Seal

CONFIDENTIAL TIBU3843

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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) 1052, 1067

SUBJECT: Heat Shield Modification Can Extend the Life of the Center Valve Cover Seal

PROBLEM:

The high temperatures of the exhaust system can adversely affect the components adjacent to the exhaust manifold and turbocharger. Excessive temperatures can reduce the life of the valve cover seals and result in oil leaks. The center valve cover seal is most susceptible to heat damage as it is nearest to both the exhaust manifold and the turbocharger.

SOLUTION:

Improvements are being developed that will increase the effectiveness of the 191-1041 Heat Shield Group. The shield in this group protects adjacent components from the high operating temperatures of the exhaust manifold and turbocharger. The shield may be extended to better protect the center valve cover seal. Although this improvement is not completely developed, a change can be made to the 221-3236 Shield Assembly to better protect machines during this development period.

Note: Earlier machines used a 191-1040 Shield Assembly which has been cancelled and replaced by the current 221-3236 Shield Assembly. The current part includes an extension that also protects the 9N-0720 Rubber Elbow on the combustion air inlet to the turbocharger. The proposed field modifications should be made to the current shield assembly that offers the best available heat protection.

Illustration 1

Fabricate plate (A), as described in Illustration 1, from steel plate at least 3mm in thickness.

Illustration 2

Weld plate (A) to a 221-3236 Shield Assembly, as indicated in Illustration 2.

Note: The 172-8027 Seal and six (6) 173-2390 Fastener Assemblies for the center valve cover should be replaced if it leaks or is thought to have been exposed to excessive temperatures. The performance of the heat shield modification can be best evaluated with a new center valve cover seal and fasteners.

A Service Magazine article will announce an improved heat shield once the heat shield is in production.