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Haven't done much research on this, but does anyone know if the V6 is an interference engine, that is piston TDC is timed in conjunction with valve timing to prevent collision of valves and pistons in the head? I know the cams are chain driven rather than belt driven, but still interested in finding out. What about the I4? :?: :?:

OC
 

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For what it is worth, the service manager at my local Toyota dealer told me that the V6 is a NON-interference engine. I would like to see it in writing somewhere, but OTH with a chain drive the probability of the cams stopping while the crank continues spinning is near zero.

How many timing chains break? I've never heard of even one. But LOTS of timing belts break.

An interference engine isn't called that because of the way the valves are timed - it has to do with the amount of clearance between the piston crowns and the valve heads. Too little clearance and the parts will slam together violently when the valves stop and the pistons keep turning. The result is bent valves, and damaged guides and pistons.

A broken belt on my interference Audi 1.8T engine would cost me $3000 for a new cylinder head plus labor. And hopefully the pistons wouldn't be gouged too badly.... A broken belt on a non-interference engine like a Subaru will just result in a tow job and about $200 parts and labor to replace the belt(s).

John Davies
Spokane WA USA
 
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