Maybe a silly question but I did a timing belt recently on my seat ibiza 6L (rebadged fabia mk1) with engine code BBY (1,4 litre petrol 75 hp) and accidentally rotated the crankshaft backwards  a few rotations trying to get the crank pulley bolt off (original factory bolt), the crank pulley holder I used slipped a couple times and I didn't realize that the crank was rotating and not the bolt. I eventually got it off and change the timing belt and tensioners and it fired up and ran fine, but it does make me wonder if it's ever a good idea to rotate the engine backwards?

 

Suppose I stall on a hill and start rolling backwards and the car is still in first gear, the engine would of course start to spin backwards, would this slacken the timing belt or cause it to jump timing somehow?

 

Haven't noticed anything strange and I've driven a few hundred miles so hopefully everything should be fine...

Edited 4 August, 20232 yr by Carproblems

Not a problem on belt driven engines, only worn chain drives are at risk.