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CAT Acert 4.4l Diesel engine issue

Hey guys, first post. Hopefully this is the right place.


I repair and maintain various machines and heavy equipment for friends in my spare time. The other day I was re-wiring the engine wire harness for a friend with a wood chipper. It was a 4.4l diesel "ACERT" caterpillar engine and I'm not sure what the make and model of the wood chipper was... Terex.. woodsman.. I don't recall.


Anyways, the engine wire harness had melted in several places due to fires which occurred under the 'hood' after the machine had been operated by employees who neglected to clear wood dust from the top of the engine. After replacing a few melted wires and sensors, I had to remove the valve cover to replace the injector wiring harness plugs. 


While I was in there, I noticed a few yellow plastic parts seemingly between the rocker arms and the valve actuators. I also noticed a few yellow plastic parts which were NOT in the valve train where they should have been. The yellow plastic parts I am concerned with were floating around loose under the valve cover. I picked out the pieces as best as I was able, and put the machine back together for return to the customer and further operation.


This has been bothering me ever since. Is anyone familiar with this engine and is this a common issue? Does anyone have any information on what may have happened and how to fix it? 


I can post pictures and a schematic if that would help. I want to fix this machine properly to prevent a more serious issue which could arise in the future.


Please help. Thank you.