Petrol mower problems.

[Retired]

Hi,

A chum has just started a gardening business working from home. He's bought a van and is buying tools and equipment as required; obviously one important piece of kit is a decent lawnmower so he bought a second-hand rotary petrol mower paying £100 for it.

Unfortunately he is experiencing problems with this petrol mower in that it keeps bunging up with wet grass clippings forcing him to rake the lawn after cutting? He has been back to the lawnmower supplier and explained the problem.

Their reply is that he has been cutting wet grass on too low a height setting hence will have bent the crankshaft?

I've never heard of a petrol mower bending a crankshaft due to cutting wet grass; this just doesn't sound right to me. 27 years ago Bron and I bought a new petrol rotary mower this being an Alko knowing the bungalow we were moving into had a large steeply sloping rear garden with waist high meadow grass. This grass also contained just about every kind of tall weed possible. It was incredibly hard work and we ended up with over 30 large bin bags of clippings/debris. The mower was hitting stones; roots and twigs etc but now 27 years on our mower is still working although I'm currently giving it a well deserved service.

My own thought is that cutting wet grass should not be attempted with the grass box installed because our mower also refuses to throw the wet clippings into the back of the box making mowing a misery.

http://forums.digitalspy.co.uk/showthread.php?t=671130

I had a quick browse on the web and found the above site; post #5 agrees with my findings whilst trying to cut wet grass with the box installed. Isn't it standard practice to brush wet grass first before cutting if the grass must be cut wet? I'm not a garden expert but a bent crankshaft sounds suspicious to me. I did suggest to my chum when he told me of his plans to buy a brand new petrol mower from Screwfix which should easily see him through his first year of gardening even if it did invalidate the guarantee due to the mower being used for business purposes?

I've had a quick look on YouTube and stand corrected because this appears to be a common problem with bent crankshafts?

https://www.youtube.com/watch?v=wjSZu2hlmsk

My chum is being charged £50 to have his mower repaired; will it behave any differently after the repair?

Kind regards, Col.

[Refugee]

I would have taken the machine screw out of the center of the blade and replaced it.
That is much more likely to be bent than the crank shaft.
In that video he was using the thing with a weakened machine screw and the risk of the blade falling off and chopping his feet.

[Rascal]

Wouldn't a bent crankshaft cause severe vibration?

I often mow my wet lawns (UK climate - you cant avoid it) and must admit the mower clogs up on occasion and even stalls - once cleaned up its ready to go again.

[Retired]

Hi,

Thanks Refugee; I've never worked on a petrol mower or stripped one down so all this is new to me but I see there are a number of YouTube videos on the subject with owners thinking they have little to lose so are reverting to rough practices which seem to work?

Yes Rascal a bent crankshaft is sure to cause vibration and if left running in such condition will soon knock the bearings out as well. As you rightly say we have little choice here in the UK but to mow wet grass.

I've just been draining the oil on my petrol mower and it's now ready for new oil once I get out to buy some. The old dirty oil can be seen in the bottle and I've used some of this oil to soak a rag which I've wiped the mower with making it look 100% better and cared for. This mower is 27 years old and still cutting our grass year on year; it was bought new and has been a good investment. All the original wheels broke long ago hence the strange wheels but as long as it cuts our grass I'm happy.

Kind regards, Col.

       

[singlepentode69]

I have never heard of it bending the crankshaft maybe an old tale used by the repairers as an excuse to finding the fault a bit like the bad radio repairers who said the valves had gone to bump the repair price up. I have always brushed the grass to displace the water then cut it in three cuts a bit like sanding going through the course to get a good finish.I have in the past cut very long grass with the back deflector held up with string and using no box but probably not a safe option if stones are presant and then raking up the grass before doing a final cut.Moutfield used to make a red mower which had an option for using a box or using the Shute when cutting wet or long grass
Regards
Robin

[singlepentode69]

An Allen Sutherland was good for long grass many a field I have cut with one
Regards
Robin

[Retired]

Hi,

Thanks Robin. I too sometimes use my mower with the rear deflector held open and in picture #2 the string and hook can clearly be seen. This as you say is definitely not a safe option because even a pine cone can bring tears to eyes if the cone is thrown against a shin; things picked up and thrown out by the blade are like missiles.

If a crankshaft is distorted then I would have thought it would involve a complete engine strip down; the crank set up on accurate "V" blocks and an hydraulic ram used to apply pressure in order to re-align it against a DTI; this would be the way I would bring about such a repair but then I'm not a big hammer guy?

Kind regards, Col.

[singlepentode69]

That sounds like an sensable option Colin the type of thing I would try or try to turn in a lathe if not too bent skimming a few tho off.
Regards
Robin

[camallison]

Hi,

Thanks Refugee; I've never worked on a petrol mower or stripped one down so all this is new to me but I see there are a number of YouTube videos on the subject with owners thinking they have little to lose so are reverting to rough practices which seem to work?

Yes Rascal a bent crankshaft is sure to cause vibration and if left running in such condition will soon knock the bearings out as well. As you rightly say we have little choice here in the UK but to mow wet grass.

I've just been draining the oil on my petrol mower and it's now ready for new oil once I get out to buy some. The old dirty oil can be seen in the bottle and I've used some of this oil to soak a rag which I've wiped the mower with making it look 100% better and cared for. This mower is 27 years old and still cutting our grass year on year; it was bought new and has been a good investment. All the original wheels broke long ago hence the strange wheels but as long as it cuts our grass I'm happy.

Kind regards, Col.

Alko - a fantastic brand, and VERY robust. Ours is a similar age, and the wheels went on our too. I bought a new set from the UK spares stockist at a reasonable price. Hard to believe, but they still carry spares or updated parts.

Colin

[singlepentode69]

Atco rotary mowers were indestructible
Regards
Robin