OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines Honda GV100 LawnMower Engine Problem

Hi All
My Lawnmower Honda GV100 engine broke down when I hit a large lump of wood and is still working but with an awful metal grinding noise. I can freely move the blade by hand with very little effort.

Can anyone share any manuals on this engine as I wish to take apart and repair. Many Thanks.

Hi singinmgr, welcome to Outdoorking.

There is an abbreviated version of the Honda workshop manual available as a free download, here:
http://www.honda-engines-eu.com/documents/10912/31965/1531/209cf374-f289-4c75-9fea-6ecb5353e447

However I do not think this will help you with your present problem. I suggest that you should begin by removing the blade plate complete with blades from underneath your mower. Be sure to disconnect the spark plug lead first, then tip the mower toward the oil filler, not toward the carburetor, to get access to the underside. With the blade plate removed, put the mower back on its wheels and reconnect the spark plug lead. See if the grinding noise still occurs when the engine is run without the blade plate.

Usually when you run over something with a mower it is the blade plate and blades that are damaged, though in severe cases the crankshaft may be bent as well. However crankshafts usually bend at the lower main bearing, which does not cause major distortion inside the crankcase. A bent blade plate may not make contact with the mower base unless the engine is running.

If the noise disappears when you remove the blade plate, the crankshaft may still be bent. You can check this by rotating the engine slowly, with spark plug lead disconnected, observing whether the tip of the crankshaft extension runs out of true.

(Note for archives: in general, do not run engines with aluminium flywheels without the blade plate: they may kick back when you pull the starter. Usually engines with cast iron flywheels will not kick back strongly.)

Grumpy thank you for your response. I think you may be right I will follow your steps and check this out. Thinking about if the engine had conked out it would not start or continue to run. I may have jumped to conclusions too quick.

I don't think engine internal problems are likely, but you may still have bent the end of the crankshaft (though it isn't easy to do that). If you have, the mower won't be worth fixing unless you can find a junk one with the same engine. Moving an engine from one mower frame to another is dead easy (providing the frames both had that same engine type originally), and even moving the crankshaft from one engine to another is worthwhile if you enjoy spanner work (it should take well under an hour), but the value of that old engine is vanishingly low. However if it's just a bent blade plate, you can practise your panel-beating skills on it for no cost and with no risk of damaging the mower itself.

It's all fun unless you spend money on it - then you're likely to end up feeling foolish, since you could buy a newer, better mower for very little.