Q: Dismantle, yanmar 2GM20F mated to MECC-ALTE MR2 through a MD35 interface?

[vas]

OK, that's a tricky one, bear with me!

yanmar 2GM20F decided it's had enough and wont start after only 1000h. Was difficult to start and had low compression for the last couple of years at least.
Said engine runs a 3000rpm generator so governor stuck to almost WOT all the time. Engineer said it's typical issue stuck rings.
Indeed removed all paraphernalia, as well as cyl.head cylinders are nice and smooth, no probs, valves/seats almost perfect, so stuck rings it probably is.
Assembly is on a reasonably difficult spot against the e/r to lazarette bulkhead with decent access on three sides, and just 80mm from the top!!!

Was worried how I'm going to handle the motor/generator combo and how I'm going to take them apart, but on closer look, the U-shaped frame running under the combo has an extra bracket where the generator is bolted on. Engine has 4 mounts to this frame and the elastic mounts are between the frame and the tray it's bolted on.
So simple job to undo the four yanmar mounts, undo the 8 M8 bolts that hold the MD35 (I guess it's some sort of ISO standard thing...) to the motor and slide the yanmar out keeping the generator secured on the frame.
Alas, not that easy, I mean I have an easy 2mm all around, a bit of hammering or fitting a massive flathead screwdriver and trying to lever shows that things are somehow connected...

Now, before removing the 4 M8 (or smaller) bolts that hold the generator casing to the MD35 interface and taking all things apart with dubious results in terms of putting it back together... anyone familiar with this thing???

A few pics from today:

and a link to online drawings of the generator MR2 and the MD35 interface:

https://www.hsaoy.com/2.4_Generaattorit/2.4.1_Meccalte/mr2.html (bottom of page inset is the MD35 which doesn't look good...)

Now looking at generator x-rays online it seems that the rotor shaft has a woodruff key, so in theory I'd expect that to slide out.
However, on the MD35 interface, there's clearly a disk plate engaging to engine. SAE 5 is mentioned and disk dia of 314.3mm is shown.
Mind I haven't the faintest idea of how the outlet side of the yanmar looks like. For sure there's no "clutch" as such as it's always mated to the generator.
On the pics you can see a biggish cylindrical piece lightly rusted, smooth all around, no key on it (I think I did a whole rotation of the crank!) so no outside access.
I'm worried that once I try and remove the generator I'll have to take the whole thing apart and remove the back side and the stator and end up with the rotor mounted on the crankshaft...

Anyone knows if that's the idea of taking these things apart, and if so anything I should take care of when doing it?

cheers

V.

 

[ARE]

Normally with generators you need to remove the end bell which contains the rear bearing, then remove the outer stator by sliding it off the rotor. This then allows you to unbolt the flywheel flexplate from the flywheel.

 

[Portofino]

Stuck rings - WD 40 overnight. Is there a crank bolt you can get purchase on ?

I tend to run my geny every month. Salt air can get into the cylinder ( yanmar 1GM ) through open exhaust valve .
Main engines get a frequent run out too .
There was a thread on winter off season engine activity recently it divides opinion. Those with inter cooler corrosion anxiety that run freshwater through tend to leave them redundant over the closed season . That’s not proper winterisation btw .

 

[vas]

Normally with generators you need to remove the end bell which contains the rear bearing, then remove the outer stator by sliding it off the rotor. This then allows you to unbolt the flywheel flexplate from the flywheel.

thank you Anthony, I was afraid that's what I had to...

Any caveats on this?
any fancy springs and bushes ready to pop-out?
Need extractors for bearings?
Do I have to mark anything in order to put it back as it should?
Finally, I'd expect there are accurate matings between the crankshaft and generator rotor so that when I put everything together it's still going to be balanced and not wobble to destruction on first run!

I'll have a go tomorrow if everything is straightforward.
Wonder if I can access the bolts on this disk from the vent openings and avoid the dismantle!

cheers

V.

 

[vas]

Stuck rings - WD 40 overnight. Is there a crank bolt you can get purchase on ?

I tend to run my geny every month. Salt air can get into the cylinder ( yanmar 1GM ) through open exhaust valve .
Main engines get a frequent run out too .
There was a thread on winter off season engine activity recently it divides opinion. Those with inter cooler corrosion anxiety that run freshwater through tend to leave them redundant over the closed season . That’s not proper winterisation btw .

Porto,

it's complicated... All this heat/cool cycling at 3000rpm is killing these small yanmars.
I'm setting up a system to avoid that (starting at idle, let it warm up for a couple of mins, then up the revs to 3K and when turning off, idle for 3mins and then turn off)
Apparently it's an issue with 2pole generators non existant in 4pole ones (they only run at 1.5k rpm though...)

When I finalise and test it I'll let you know.

cheers

V.

 

[Portofino]

After an overnight soak of the cylinders can you attach a oil filter removal tool to that rusty shaft / f wheel and turn that ?

 

[Portofino]

Porto,

it's complicated... All this heat/cool cycling at 3000rpm is killing these small yanmars.
I'm setting up a system to avoid that (starting at idle, let it warm up for a couple of mins, then up the revs to 3K and when turning off, idle for 3mins and then turn off)
Apparently it's an issue with 2pole generators non existant in 4pole ones (they only run at 1.5k rpm though...)

When I finalise and test it I'll let you know.

cheers

V.

Thought these paddy pump engines were and can run in extremely harsh environment unloved .
So a loved one on a boat should be ok ? Ie regular oil changes etc .
Manual does suggest run it for few mins then turn on demand and similarly at the end turn off demand and let it cool for 5 mins before killing the engine.
Mines actually a 2600 rpm . If the oils correct a low first number it’s thin when cold ( esp synthetic) to rapidly circulate- get under those rings splash about when it’s cranking a few seconds before it fires and heat arrives on the scene.
I use 15/ 40 semi synthetic- replaced every year .

Lack of use that kills them .

 

[ARE]

thank you Anthony, I was afraid that's what I had to...

Any caveats on this?
any fancy springs and bushes ready to pop-out?
Need extractors for bearings?
Do I have to mark anything in order to put it back as it should?
Finally, I'd expect there are accurate matings between the crankshaft and generator rotor so that when I put everything together it's still going to be balanced and not wobble to destruction on first run!

I'll have a go tomorrow if everything is straightforward.
Wonder if I can access the bolts on this disk from the vent openings and avoid the dismantle!

cheers

V.

I am not sure if your unit is brushed or brushless? But if brushed you will need to remove these first.

No marking is required as the unit is balanced separately to the engine, so you can refit the rotor in any position.

Regards Anthony