Motorhome Exhaust Manifold and Plug Wire Failure
Posted by: Tony Howard (Tony H), Monroe WA ... thanks Tony!
Chevrolet has determined that right side exhaust manifold and right side spark plug wire failure may be the result of inadequate air flow. This is due to the absence of a wheel-well panel on the right side front wheel opening. This situation allows necessary engine cooling air flow to exit the engine compartment prior to passing the exhaust manifold and spark plug wires and thereby cooling the manifold and spark wires as occurs on the left side of the engine compartment.
This condition can be corrected by fabricating a metal panel similar to the one used on the left side of the vehicle. Adding the panel forces the air flow to pass along the right side of the engine compartment thereby providing a cooling effect and eliminating repeated right side manifold and spark plug wire failure.
Care must be taken in the design of the right side panel as to provide proper clearances around any hoses, wires and engine dress items and also to provide clearance for the tire throughout its movements. The panel should extend rearward to a point parallel to the number seven spark plug wire. The panel should be shaped and positioned similarly to the left side panel currently installed on the vehicle. Care must be taken to leave an opening at the rear of the engine compartment to allow cooling air to exit the engine compartment as on the left side panel.
Note...the manual includes two illustrations in this section, but they simply show air flow and don't give any construction hints
Excerpted From the Chevrolet Motor Home Chassis Service Guide 1988 editionMore on this here!