Crank turned backwards by mobile mechanic
 

A mobile mechanic to remove the failed auxiliary belt behind the crank pulley put a big spanner on the pulley and wound it backwards. The BMW 320 had been running ok with out the belts before but after would not start. Talking to my garage they say a write off yet only done 120 k and regularly returned nearly 50 mpg. Do you think garage right as so sad to loose. My present motor is a V6 of same vintage returning half the mpg.

I can't see how hand turning the engine in the wrong direction is going to do any damage. When you say would not start what do you mean, won't turn over, won't fire, what?

On some chain driven diesel engines it can be a problem - IIRC Mercedes Benz had non ratchet hydraulic tensioners on the cam chains on some engines, and if turned backwards all the slack built up in the wrong place allowing the chain to jam or the valves to hit the pistons.

Haven't heard of any similar problems with the M47R, and I'd be amazed if there were given there are two separate timing chains on our engines, but if the OP has been told similar damage has occurred then worth carrying out a compression test.











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Done this myself, if it started before, and not after, the mechanic has forgot something, or damaged something. How does a garage say it is a write off.

If it is something the "Mechanic" has done and damaged the engine then I would be after the "Mechanic" to sort it out at his cost.......:xmas-smiley-008:

I have done it before, many times, last time on a M47, every time I tried to move the tensioner with the spanner, it come loose, so I wound the belt on turning the crank. Don't know why the mech would turn it opposite to its normal rotation. I always believed, the M47 chain tensioner is capable of allowing the crank to be turned in the opposite direction, otherwise the cam would chatter in normal rotation.

I agree. And I cannot see any ill effect from that either.