PISTON FAILURE

PISTON - WORN OUT

Excessive wear on pistons is a normal condition brought about by high mileage and use. Premature wear is usually a result of poor air filtration or lack of service to air cleaners and pre cleaners. Under severe dusty conditions the service interval should be changed so as to maintain good intake filtration at all times. If the damage occurs soon after an engine rebuild the oil should be checked for abrasive contamination from cylinder honing. This is the most common cause for pre mature piston skirt wear following a rebuild. The other main problem following a rebuild is a damaged or faulty intake system. Check all components of the intake system, especially on vans and forward control vehicles where the induction system includes a system of flexible hoses.

Quite often the flexible hose is overlooked and was faulty causing the problem in the first instance.

When airborne contamination is the cause the rings will usually be more worn than the piston skirt. When the contamination is an abrasive in the oil the ring and skirt wear will both be very severe and usually over a much shorter period. A good indicator of abrasive oil contamination from honing is when the oil expander rails are worn down to the expander and the expander is making contact with the bore. This damage will normally occur within the first 1000 kilometers.

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Piston skirt finish has been worn off and measure below minimum