Why rotate the engine?

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Mr Micawber
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Why rotate the engine?

Post by Mr Micawber »

Hello everyone,

I'm in the middle of renewing the timing belt on my C3 1.4 litre 8 valve KFV engine and one thing puzzles me, probably because my other cars have always had a chain.

All the instructions (Citroen, Haynes and Gates the belt manufacturer) say that the engine should be rotated by hand four (Citroen) or ten (the others) times after fitting the belt and setting the tensioner at it's maximum setting. They then say that the flywheel and camshaft sprocket locking tools should be re-inserted and the tensioner reset to its 'normal' setting.

The bit which really worries me is that they deal with the possibility that the locking tools cannot be re-inserted properly; in other words, when the timing has somehow been lost.

Does anyone know the purpose of this engine rotating operation? It seems to me to just introduce an unnecessary risk.

Simon
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xantia_v6
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Re: Why rotate the engine?

Post by xantia_v6 »

If the belt was not sitting on each pulley in its natural alignment (eg not pushed equally onto each wheel), then some of the runs between pulleys would be marginally the wrong length. Rotating the engine allows the belt to find its natural alignment.
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Mr Micawber
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Re: Why rotate the engine?

Post by Mr Micawber »

Thanks xantia_v6. I have taken the plunge and done it. You're absolutely right! The result was that the belt aligned itself more centrally on the water pump and camshaft sprocket wheels.

I would have achieved the same result after re-assembling by turning the engine on the starter, but I suppose that the turning by hand is a sensible precaution in case something isn't quite right.

Simon