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525 TDS E39 1997. Does anyone know if this is an "interference engine" or non interference?
Cheers to all.
 

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I think interference means that the pistons can hit the valves because the valves protrude into the swept space of the piston. Under normal timing the valves move out of the way, but if the timing is out (eg timing chain snaps) the pistons can strike the valves.

A non interfearence engine would be one where the valves and pistons could never meet because the valves are never in the swept space of the piston.
 

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I am slightly naïve here , so you mean piston at top dead and valves open and would never touch even with valve timing wrong which would be same as snapped timing chain or belt etc is this what you mean.
 

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I am slightly naïve here , so you mean piston at top dead and valves open and would never touch even with valve timing wrong which would be same as snapped timing chain or belt etc is this what you mean.
I would be hard to find a free rotating diesel engine because of high compression ratio in diesel inevitably making the piston / valve clearance small.
 

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I am slightly naïve here , so you mean piston at top dead and valves open and would never touch even with valve timing wrong which would be same as snapped timing chain or belt etc is this what you mean.
Yep - exactly!
 
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