Classic/Antique Car Repair: 300xz 1988, interference engines, interference engine


Question
I have a non turbo 1988 v6 twin overhead cam. The timing belt broke and I wanted to know if the valves clear the pistons on this car. Could I just put on a new timing belt and go or did the valves get bent? Thanks

Answer
Hi Dustin:
Sorry to hear about your timing belt. Well, the answer to your question is based on "Belt" or "Chain". If you have a timing belt, then you have a "Interference Engine". However, if you have a "Timing Chain", it is "Non-Interference"

An interference engine is an engine design that has been avoided by some manufacturers for well over 80 years. General Motors, Chrysler, etc., typically use a metal chain-type timing belt on push-rod engines often called a timing chain. Rather than use a steel timing chain, interference engines may use a rubber timing belt with its limited life, where as steel timing belts typically last 150,000 to 200,000 miles or more.

So, when the "Belt" breaks, some of the valves stuck in their open position will collide with the top of the pistons, thereby breaking or damaging them.

Belt = Bent Valves, Chain = NO Bent Valves.