Rick's b.log - entry 2020/10/17

Playmobil Expo

But, like most everything else this year, cancelled.

Today's b.log entry is all about mechanical things,
to demonstrate I'm just as dangerous with a spanner as with a keyboard. ☺

Evening mowing, and mower repair

As I went shopping, I got around to the grass at about ten to seven. Sunset would be in about half an hour. Luckily, I added a light bar earlier in the year, having already forseen this eventuality.

It wasn't long before I needed it.

Light bar on mower.

And it wasn't long before I really needed it.

Light bar at night.

Towards the end, the light dimmed and started to flicker. Something wrong with the light unit? I disconnected the mower blades and reconnected them. The engine hiccuped under the change in load, and this was reflected in the light behaviour. Okay, so there's something wrong with the battery and the lights are being run off the alternator.
When I finished mowing, I took a look and, sure enough, the machine was utterly dead. No power at all. A multimeter showed the battery had charge. So, did the light blow a fuse or something? Is there a fuse?

A few minutes of poking around, and I found the cause of the intermittent electrical problems:

Dud wire.

There was no way I was going to get that rusted bolt undone. As the negative wire only needs to connect to the chassis (the wires you see carry positive voltage, the entire bodywork is the negative side), all I needed to do was stick a solid bolt in to hold the wire in place.

Replacement connection.

It's a big 8mm bolt with two large washers for two reasons. The first is to hold the wire firmly in place, and the second is to carry enough current to crank the engine (which could be in the range of dumping 50-100 amps into the starter to get the engine turning).

Brownout

The Pi2 takes little power, the power stored in the five-output power brick kept that lot running, and now since my Livebox is connected to a dinky UPS, that kept on going too.

Felicity servicing

As it happens, I identified the two belts (main drive belt and alternator/cooling belt) as consumables most likely to break that are fairly easily fixable (as in, not a mechanical failure).
So, guess what I just happen to have in the back...

Spare belts.

The spanner that I keep up front in case the windscreen wiper bolt comes undone is a dual size 12mm/13mm. This is intentional. The 13mm is for the wiper bolt. The 12mm is the size of the bolt that tensions the alternator.
And that bolt that you can see beside the belts? It's a 6mm × 80mm. It is used like this:

Bolt to open the variateur.

Around the middle part of the gearbox variateur are three small holes. One accepts a bolt. Screw it in, and it will push on the inner plate to force it apart. Do this, and the belt will loosen and will be able to be either removed or put in place without dismantling the bell-shaped variateur on the engine.

This will be a tedious task for me as my bolt has a screw thread. It's much better to have a hex bolt head so you can use a ratcheting spanner on it, however my local DIY store doesn't have these big ones with hex heads, and I'm not feeling inclined to go into Châteaubriant just for a bolt.

Trust me, that belt did not cost anything like €70. Even the most deluxe bomb-proof reinforced German technology available at Nessycar doesn't cost anything like €70!

Rotavator repair

Perhaps I ought to rephrase that. After two cranks it started having not been used in something like twenty years, and with twenty year old petrol in the tank.

It started, it ran...

Rotavator in action.

...and it died spluttering in a cloud of smoke.

Now, you really have to be some kind of malicious bastard in order to kill one of these engines. So I dragged it back to the shed and cranked it. Nothing.

Well, not exactly nothing, it sounded like it was trying to fire but just not getting there.

I removed the air filter, and the engine fired and died.

I wedged a screwdriver into the carburettor to hold the choke valve open. The engine fired and ran hesitantly and slowly. Okay, the engine itself isn't dead, it's the carburettor.

As it was gone sunset, I put everything away until this morning.

This morning I looked at the petrol, and got the shock of my life (slight exhaggeration!).

Looking in the petrol tank.

There's only one sort of petrol that's that colour - two stroke fuel/oil mix. The hell is that doing in a four stroke engine?

As there was very little, I tipped it all out in a dank corner and resisted the urge to toss a match at it. Before you complain about the environmental impacts, I'll point you at, well, any local farmer. There wouldn't even have been enough to half fill a teacup, I've probably spilled more than that filling mower tanks in my lifetime.

The next task was to strip down the carburettor and give it a clean. I was expecting the carburettor to maybe have gunge blocking the float value or the little needle. I really wasn't expecting whatever the hell this is.

Carburettor.

A moment of Googling shows that it is a type of carburettor known as a "pulse jet", that is actually rather clever. If you look at the photo, you'll see that there is a part moulded into the fuel tank, and a part that screws on to that with a little rubber diaphragm in place.
If you look at the tank side, there's a part (upper right in the photo) like a shallow pan. This is actually a fuel pump. It works by a spring where the suction of the air in the carburettor on the intake stroke sucks the diaphragm up, and the spring pushes it down on the other strokes. If you look at the diaphragm, you might spot two little flaps to either side of the fuel pump. These flap open and closed to ensure that fuel passes through the pump in one direction.
Fuel is constantly pumped into the 'M' shaped section. A shorter suction pipe (the big one goes into the fuel tank) descends into this reservoir, and suction from the engine's intake pulls fuel up the pipe and into the carburettor.
Now, you might be wondering what happens if the pump just keeps slinging fuel into the reservoir. Well, nothing. Just to the left of the shallow pan is a slot. This is the overflow. Any fuel that overflows just falls back into the tank.
I'm not sure about the purpose of the second larger bowl and the big spring thing. The other end appears to be connected to a throttle valve, so I'm just going to guess that it's some sort of automatic engine speed adjustment.

Put it all back together, and...

I should point out that if the rotavator hasn't been used in twenty years (maybe even a quarter century), then I haven't used the rotavator in twenty years (maybe even a quarter century). When it was munching its way through dirt, all was fine. But the moment it hit a sturdy bit of root, it was bouncing around like a possessed balloon in a gale. And if the ground contained large stones, oh my.

Friday, at work, I think I must have been walking around like a Cyberman. My shoulders hurt, my arms hurt, my back hurts... now, it was worse yesterday!
To think, my neighbour was an eighty-something year old woman dressed in the way of all old French mémés - a sort of floral pinafore dress, plastic clogs, and tearing through the ground like a frigging boss. Did I mention she was eighty? Or that her rotavator was larger than mine?

It is an experiment to see if breaking up the roots will stop the brambles in the section of ground that I cleared. You can see in the photo below the part that I did turn over (where brown meets green). God (other deities may apply) help me if I need to turn the rest of it. Maybe I should make myself a DIY plough out of a log with bits of metal bolted to it, tie that to the back of Felicity, and just drive in circles for a while?

Still, mower electrics fixed, rotavator fixed, car to be fixed (by a real mechanic).

Now for tea, doughnuts, and either "The Haunting of Bly Manor" or ... something. So many choices, so little time.

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John Williams Eglwys Bach, 18th October 2020, 10:48

Felicity Servicing was a little disappointing as a topic.    Your story of the girl who helped replace the gutters and her apparel was much more stimulating! But that is probably pre-blog.

Rick, 18th October 2020, 16:54

Pre-blog to the point where mom and I probably told you of how little she was wearing (and how flustered she was when the good looking meter reader turned up) in person. Very pre-blog. And no, it wasn't at all stimulating. There are words, none of them polite.    As for "servicing" as a euphemism for sex, do remember who's blog you're reading. The ones around here most likely to have anything resembling sex are the cats or the wildlife...

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