Mountfield R28M ride on Mower not starting (Again!!)

sujsuj

I've been getting help from the forum for the past 2–3 years regarding my Mountfield R28M ride-on mower. This time, I took some precautions—such as starting it occasionally during winter—to avoid issues.About a month ago, I managed to start the mower and moved it a bit. Since it was still winter, there wasn't really any need to use it then.

Now that it's summer, the Mountfield R28M is letting me down again! I thought I could fix the issue by charging the battery, but that hasn’t worked. I’ve charged the battery for several days, but the mower still won’t start. It only makes a vibrating sound when I try.

Could someone please help me figure out what to check or what might be wrong?

Thanks very much!
Video included.

 https://youtu.be/Y03bczPx92o

sujsuj

https://youtu.be/Y03bczPx92o

Green_hopeful

I am guessing its a petrol mower. Petrol goes off quite quickly. I used to drain my petrol mower for the winter. Vague memory but i think it damages the carburettor. 

Lorian

Fresh fuel (and avoiding E10) always recommended but that doesn't sound like a fuel issue as it's not cranking. If we are sure the battery is good I would suspect the solenoid.

daveyjp

That's a starter problem.  Battery or starter motor.

Section62

Starter motor most likely, we need the make and model of engine to confirm.

Meanwhile, stop trying to start it until you've found and repaired the fault.  The "vibrating" sound is quite likely to be the starter gear trying to grind itself into dust... if so that could become a replacement rather than a repair.

WIAWSNB

First check that the engine is not seized.

This, however, is usually down to either a flatish battery, bad HD cable connections from the battery to the starter, or possibly the starter/solenoid itself. 

Easy way to check is to 'jump' it. Is the mower battery 12V? And do you have jump-leads, SS? If so, try jumping from your car battery (taking all the usual precautions). If the mower now fires up cleanly, then assume the mower battery is feeble. But if the same noise occurs, then check the mower battery, and all the HD cables and connections from the battery to the solenoid and starter motor (these last two may be part of a single unit).

It sounds like a pulsing solenoid rather than the actual starter motor - a bit of a classic early-morning soundtrack in the 60s and 70s

The wee key switch is 'light-duty', and cannot carry the hefty current being drawn by a starter motor. So, they fit a relay - the 'solenoid' - in between this switch and the starter motor. The key switch is strong enough to handle the few amps required by the solenoid, and this then 'clicks' audibly as it closes a couple of much heftier switching contacts inside. This heftier switch can then handle the 100+ amps drawn by the powerful starter motor as it turns an engine.

If the battery is weak, however, or if the cable connections are poor and not allowing a full current to pass, what often happens is that the key switch engages the solenoid as before - which clicks - but then the large current demanded by the starter 'pinches' the battery current, and it isn't enough for the solenoid to remain enagaged - it therefore clicks again as it releases. Once it releases, the starter is not getting its supply, so there is now enough for the solenoid to engage again - click. But, once it engages again, the starter does youknowwhat all over again. So, the poor solenoid just pulses like this.

ButterCheese

No offense but if you don't know what's making that noise then it's unlikely that you know enough to diagnose and repair the problem.  As the above poster said, it could be electrical or simply that the starter motor is partially seized/jammed so not engaging fully with the fly wheel.  You can remove it and test/repair on a bench but if I were you I'd take it to a reputable garden machinery centre.  You can chance it and fit a new starter motor but if that's not the issue then you've wasted £100

WIAWSNB

SS is very capable of tackling some pretty complex tasks, given guidance.

15-pages worth ought to do it.

ButterCheese

In that case, I'd first check the woring loom for damage; it's common for vibrating things like lawnmowers to rub through wires if not routed or covered correctly.  I'd also look at all the earth points, make sure there is good contact and no rust/grime.

I'd then take the starter motor out and put on a bench; apply power and see if the bendix drive is fully extending.  It could be that it's partially jammed and not engaging fully with the flywheel.   Could be what the grinding noise is

Section62

ButterCheese said:

...

I'd then take the starter motor out and put on a bench; apply power and see if the bendix drive is fully extending.  It could be that it's partially jammed and not engaging fully with the flywheel.   Could be what the grinding noise is

sujsuj, first things first - make and model of the engine so we can confirm what type of starter motor it has.  There are lots of variations in small engines fitted to equipment like lawnmowers, and different types of starter motor.  There's no point removing the starter motor and applying power to check the bendix drive if your model doesn't have one.

E.g. If your starter motor is a constantly-engaged type then it is unlikely to be that making the noise and the relay/solenoid would need to come under the spotlight first.  Remember that taking things apart which don't need to be taken apart can cause new (and often expensive) problems.

If you do take the starter motor out to test it (and this applies to any medium or high-torque motor) then make sure you have it firmly bolted or clamped to something solid before applying electrical power to any part of it.  If you don't secure it, the body of the motor is likely to attempt to rotate rapidly in the opposite direction to the armature and potentially go spinning across the bench, or the workshop floor. (Newton wasn't wrong about this).  Never just lay a motor on a bench or floor and connect power.  The forces involved can be enough to do some quite serious damage - to the motor, to you, and/or to the workshop.