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

sujsuj

Green_hopeful said:

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. 

Thanks. Another interesting thing I noticed today is that the headlight, which used to work when I previously managed to start the mower, is now not turning on at all. Up until now, I’ve been using the brightness of the headlight as an indicator of the battery's condition. Since the headlight isn’t glowing anymore, could this help point to the root cause?

sujsuj

Lorian said:

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.

Thanks. Another interesting thing I noticed today is that the headlight, which used to work when I previously managed to start the mower, is now not turning on at all. Up until now, I’ve been using the brightness of the headlight as an indicator of the battery's condition. Since the headlight isn’t glowing anymore, could this help point to the root cause?

sujsuj

Section62 said:

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.

Thanks. Another interesting thing I noticed today is that the headlight, which used to work when I previously managed to start the mower, is now not turning on at all. Up until now, I’ve been using the brightness of the headlight as an indicator of the battery's condition. Since the headlight isn’t glowing anymore, could this help point to the root cause?

sujsuj

WIAWSNB said:

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.

Thanks. Another interesting thing I noticed today is that the headlight, which used to work when I previously managed to start the mower, is now not turning on at all. Up until now, I’ve been using the brightness of the headlight as an indicator of the battery's condition. Since the headlight isn’t glowing anymore, could this help point to the root cause?

Above could lead to the real cause..? When it was working well head light also was working

WIAWSNB

Section62 said:

I'm sure all of us want the same thing...

Yes, for this thread to stop by page 2.

WIAWSNB

sujsuj said:

Thanks. Another interesting thing I noticed today is that the headlight, which used to work when I previously managed to start the mower, is now not turning on at all. Up until now, I’ve been using the brightness of the headlight as an indicator of the battery's condition. Since the headlight isn’t glowing anymore, could this help point to the root cause?

Above could lead to the real cause..? When it was working well head light also was working

Possibly. It could be indicative of the same causes we've mentioned before - the ones you should be checking. Or it could mean your bulb is blown.

SS, are you going to listen to the folk on here who are giving you advice? Or are you going to continue 'doing your own thing', when - with respect - your understanding is clearly limited (eg, sending 100+ amps down a multimeter designed for 10)?*

A useful thing you have done is to disconnect the mower battery for charging, and then reconnect it; this should have highlighted whether the connections there were poor. I presume they looked 'clean'?

Phew.

Ok,

1) Remove the spark plug - you are the master of that art.

2) Does your mower have a 'manual start' option? Eg, a pully designed to take a pull-cord, like you get on outboard motors? If so, get a rope, wrap it around, and give it a steady pull. Does the engine spin?

3) If no 'manual' start option, then raise and support one side of the mower by just enough to allow you to see the blade underneath. Insert a stick in there and push it against the end of a blade to make it turn. Does it? If so, does the engine also turn?

4) If the engine does turn with either of these methods, then it ain't seized. You must check this first.

5) With the spark plug still out, the engine will be far easier to spin. So, try one go using the key as before. Does the engine now spin?

6) If the engine does not spin, 'jump' your car battery to the mower one, and give that one go.

7) Report back with your findings.

*I could be wrong - that could have been a genius test! If that battery had outputted its potential 200+ amps, your mm would have burst into flames! Perhaps it indicates that your battery is kaput as it only gently began to melt :-)

WIAWSNB

Do you have the operating manual for the R28M mower or Stiga ST350 engine? (I can't find either on line).

sujsuj

I finally found the courage to open the starter area of the mower. I discovered two fuses — a 25A and a 10A. I plan to carry out further tests to see if either of them has failed, especially since the headlight isn’t working. I suspect one of the fuses might be blown and will use a multimeter to check.

I’ll also need some replacement fuses to sort this out. I’m assuming the 25A fuse is related to the engine wiring, and the 10A fuse is for the starter or the headlight.

I checked whether the engine had stalled, and I was able to manually rotate it, so it seems to be okay. I’ve attached some photos. Thanks very much for your help!

sujsuj

Here's another update: after replacing the 10A fuse, the headlight started working! I also replaced the 25A fuse, but there was no change in the engine’s behavior.

As you’ve probably figured out by now, I’m not an engine expert — but I’m good at following instructions if someone can guide me through the diagnosis.

One striking observation from my attempt to start the engine: in the image-3 below, you can see a vertical shaft (marked as I) with teeth that rotates — that's the sound you hear when I turn the key. However, I noticed that this shaft doesn’t engage with the second set of teeth (marked II) , which I originally thought it was supposed to turn. The two sets of teeth now seem to be on different levels, so the vertical shaft is spinning freely without connecting to the second gear.

Is this just how these engines are designed to work, or could this be the clue you’ve been waiting for?

sujsuj

Green_hopeful said:

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. 

Yes petrol mower, i was able to start this 4 weeks ago there after no.