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Cranking engine backwards


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I changed the timing belt on my 300tdi the other day, but then yesterday when taking the viscous fan off, I tried to unscrew it anti-clockwise. As you'll be aware, this is actually reverse threaded, and so I just ended up cranking the engine backwards about 1/8th of a turn.

Are there any negative effects of cranking an engine backwards? Do I need to re-check my timing belt?

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Na, should be fine I guess its not advisable to rotate it fully or repeatedly as its not designed to do it really, but its all mechanicaal parts turning slowly and your just moving a set system, your injection pump is off so no fuel will be injected etc. If its ECU controlled might initially confuse the ECU as the engine wasn't as it was left when turned off, but even then it would sort itself out when you start it up.

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Oh, good news then. The timing belt was fitted at the time, yes- I was just worried it would shift the tension over to the other side of the belt.

I was surprised how little tension you had to apply to the timing belt... I hope it doesn't go bang!

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Oh, good news then. The timing belt was fitted at the time, yes- I was just worried it would shift the tension over to the other side of the belt.

I was surprised how little tension you had to apply to the timing belt... I hope it doesn't go bang!

Funny you should say that, I've just done the front end oil seals and new belt etc on my 200tdi. and had exactly the same thought, to accuratly put 19nm on something like that... rather sceptical, fingers crossed I did well enough. I've noticed my engine sounds heaps better than before, The idler pully bearings where pretty loose.

The more I have played with my 90 the more it intruges me as to the indistructability/fragility of it.

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If you ever rotate a engine the wrong way you should always manually turn it the correct way to remove the slack back out the the belt. Landy engines will be happy with this.

It won't be a issue on a landy engine as they were designed to sit on the engine when on a incline, i.e. If you park facing up a hill and leave the car in 1st gear to hold it then the engine will rotate backwards until it reaches compression.

Oh and timing belts should never really be 'tight' 1mm of deflection from firm finger pressure per 10mm stretch is normal.

Adam

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