reverse engine rotation question
 

We decided to post a question here as we face a bit of an issue. We were doing belt & roller maintenance on our 944 S2s and owner of the other S2 rotated his engine 1/2 revolution backwards by turning the engine by having a wrench attached to the crankshaft pulley bolt.

The question is did the engine suffer some damage and if - what and why? We don't understand why the engine could suffer from damage if the engine is rotated slowly backwards while belts and chains are in place. Engine is 100t miles driven US spec S2.

We haven't started the engine so we'd like to know something more of this before we do... please advice.

The main issue would be if you turned the crankshaft WITHOUT the timing chain in place. Since it is an "interference engine", where the valves and pistons share the same space, you would end up bending the valves, or worse.

If the belts/chains were on and tightened, then turning the engine forward or backward should not damage anything.

Cheers,

Keith

No damage woud be done if everything was lined up and connected (ie camshaft gear & chain).

Thanks for the replies dudes. Based on this information we don't take the engine apart, just do the normal maintenance... but hey - it's soon winter so driving season is over anyways :( approx 5 months 'till end of March...... :)