What causing the timing belt failures for these type of vehicle engine? on 2003 Ford Explorer

It started with the engine overheating. I took it to several shops and a ford dealer and they could not diagnose the engine. The overheating subsided after burping/removing air in the cooling system. Finally, I found a shop that took a thorough look at my car found that the right side timing belt guide had cracked at where it was bolted into the engine. The tensioner was worn out and the belt had stretched. The heat cause by this problem required also a major valve repairs. This occurred at around 120,000 miles. I was told by my mechanic that the engine did not show any signs of distress except of the temperature spiking up after driving a few miles.

by in Milpitas, CA on February 22, 2011
1 answer
ANSWER by on February 22, 2011
We've found the overheating is due to the incorrect thermostats being used that don't have the hole in them. Chains stretch over time plus the plastic guides fail. How often was the oil changed? We've seen dozens of engines that had extreme wear from overdue oil changes. The particulates the dirty oil is circulating wears out the bearings and scores the journals causing noise and low oil pressure.
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