I found this answer in response to the question..
Drive belt tension Flymo QS5160HW?
I've lost drive on my Flymo Quicksilver 5160HW petrol mower. The gearbox assembly/drive pulley on the drive axle seems to be free to rotate forward causing the drive belt to be loose.
Is there supposed to be a spring or some kind of fixing missing from the gearbox to keep it under tension?
I haven't stripped it down yet, but I might just set fire to it instead!
Warren
May 2008
I have had the same problem the dealer were i purchased my QS5160HW from changed the spring with what he said was an upgraded spring from flymo i have lost drive several times since and found the easiest way to replace the spring is to tilt mower towards the oil filler cap remove belt housing and drive belt, refit spring, belt and housing the whole job is completed in under 4 minutes.As i live in France it not possible to return to the dealer who is in the U.K. every time this happens but it was his service engineer who said to tilt mower towards oil filler cap and not towards petrol filler cap.
david 22160 France
June 2009
There is a spring, hope it has been retained in the drive casing rather than lost. Remove HT cap from spark plug for safety. Tip machine on its side - left will flood fuel system, right allows oil to go where it's not helpful. Remove blade - 17mm. Remove cover/guard - 8mm, three bolts. This accesses drive belt/gearbox. Tension spring is about 35mm long x 8mm dia. with two hooked ends. One hook fits in gearbox casing. Other hook goes into hole in mower's sheet metal casing. Probably easier to install spring before trying to attach drivebelt. Refit all bits removed for access, tip mower upright. Let stand for ten minutes if carb/filter has flooded. Refit HT. If spring is lost you may be better off removing drivebelt and using as an un-powered mower. Also, if the drive belt cover is smashed there's little hope of trying to continue using drive mechanism without cover as mechanism just gets gunged up with grass and belt continually comes off.
Goz
August 2008
The Garden Gnome, September 2009
