1895 Otto Vertical Gas Engine

[RayW]

Cleaned the cylinder thoroughly with Acetone to ensure good adhesion for the JB Weld. Put a thin layer into each groove, then removed excess by inserting a nylon plunger which I had machined to an exact fit with the bore of the liner.
The result has been to leave the grooves neatly filled, with just a very slight smear of JB Weld around the rest of the bore, which will be easily removed with light pressure from the honing tool. I am just hoping that the honing process won't pull the JB Weld out of the grooves.
I have also made a new gudgeon pin with brass ends glued in and ensured that the ends are well recessed within the piston to avoid any further possibility of scoring.
Just waiting for my new honing tool to arrive, then will have a go at cleaning up the bore.

[90LX_Notch]

I'm glad that you are staying with this Ray.


-Bob

[Dave Otto]

Hi Ray

The repair is certainly worth a try, I know guys do this with the large one cylinder stationary engines and have success with it; hopefully it will work for you.

Dave

[Zephyrin]

I'm not sure the hone and JBWeld would do it, I'm afraid that the resin will rapidly embed in and clog the hone, and destroy it...
I suggest you check first that the lack of compression results from air escaping trough the scores. I have an engine with scored cylinder and simply did a new piston ring (and a shorter gudgeon pin too!!) to restore it.

[Nick_G]

.
You probably know this already but the 24 hour cure stuff is far, far stronger than the rapid set version.

Although it 'says' 24 hours it still takes a few days before it's cured to full hardness.

Nick

[RayW]

Thanks all for your responses. As Dave says, the JB Weld method has been used with success on full sized engines so I see no reason why it should not work on a model one.
I don't think there will be a problem with the hone clogging as there is only the thinnest film of JB  Weld to remove and I will lubricate well with WD40 or paraffin (kerosene).
I am pretty confident that the loss of compression is via the grooves. I held up the cylinder to a strong light with the piston in situ and could see two clear spots of light where the worst grooves are on one side of the cylinder. There was no evidence of light getting through anywhere else, even through the shallower ones on the opposite side, so the rings seem to be a good fit.
I will report back once I have had a go with the hone. The aim is to just remove any excess JB Weld without taking off any metal.

[RayW]

Thanks Nick.I am using the 24 hour stuff and it will have set for several days before honing.

[RayW]

The JB Weld repair to the cylinder grooves proved very successful. Once it had really set hard after several days of curing, I lightly honed the cylinder, removing the thin film of residue around the walls of the cylinder, just leaving the grooves themselves filled.
While I was at it, I bit the bullet and made a new set of piston rings as the first ones that I had made had much too big a gap.
With the new rings fitted, compression was noticeably improved, and today, by spinning over the engine with an electric drill, I got it up and running for several short runs, although it is still not starting by hand like it was before.
I am still toying with the idea of changing over to petrol or Coleman fuel and I would be interested to hear from anyone with experience of using vapour carburettors on small engines. Also any advise on vapour carb design would be welcomed.

[Zephyrin]

Good to see that this fix works...but new piston rings need some break-in !
You may add oil to the petrol, 5%, or little more to improve compression.

A great engine, a nice build, worth these efforts !

[RayW]

Hi Zephyrin,

I am running on propane at the moment and lubricating the cylinder well to help the rings bed in nicely. The cylinder is lubricated via a drip oiler which drips into a trough around the top of the cylinder liner which has four holes in it to allow the oil to enter the top of the cylinder.
Thanks for the kind remarks about the engine.

[RayW]

The paintwork on the Otto had got pretty knocked about during my efforts to get it running, so decided to do a complete strip down and re-paint. Got a good finish on the main body but ran out of paint before I had done the flywheel. Bought another aerosol can of the same colour from the same motor accessories shop and sprayed the flywheel, only to find that it had come out a much browner (and nicer) shade than the rest, so left with no option to but strip the whole engine down again (having just assembled it all) and re-spray with the same can that I had used for the flywheel.
I have seen some very nice pinstriping on the flywheel spokes of other Ottos and would like to do the same on mine, but rather apprehensive in case I mess up. I bought a small EmBee pinstriping machine, but the stripe is coming out a bit wider than I had anticipated, so undecided whether to attempt to stripe or not. The other alternative, I suppose, is to use masking tape and a brush.
After re-painting, I added a couple of finishing touches - glued the dummy hot tube in position on the inlet block, and attached the two name badges purchased from Heinz Kornmuller.
I also bored out, and re-bushed, the flywheel, to cure the wobble due to the bore being slightly oversize. Looking much better now with hardly any runout, and I have not finally adjusted the fit of the key yet. Finally, I made a new split big-end bearing as there was slight play in the original.

[Dave Otto]

Looks very nice Ray!

Dave

[RayW]

Since my last posts, I have been tearing my hair out trying to get any signs of life from the Otto. It absolutely refuses to run, or even fire. I have tried different glow plugs, different gas pressures, different valve timings and, today, a crude vapour carb with Coleman type fuel, all to no avail.
Compression is quite low at the moment, but is no worse than it was when the engine ran OK before. I thought, perhaps, that the low compression was the problem when trying to run on Propane, hence the trial with Coleman fuel today.
I have checked the action of the gas inlet valve in the carb and it is opening and shutting off correctly, and I have checked both the inlet and exhaust valves for leakage.
Currently, I am at a total loss as to where to go next. It is so frustrating when it was beginning to start fairly easily and run quite well before.

[Alyn Foundry]

Hi Ray.

Sadly I have literally zero knowledge of “ Glowplug “ operation with IC gas/petrol engines.

What thread do they use, or are there many and which one have you chosen?

I would much prefer to see if an HT spark will ignite your mixture.

One thing at a time..... 

Cheers Graham.

[Jasonb]

Glow plug has the same thread as a 1/4" Rimfire sparkplug