1895 Otto Vertical Gas Engine

[zeeprogrammer]

Very sorry for your frustration and I wish I could help.
I'm sure many on the forum will provide suggestions.

Please keep at it. It's a beautiful piece of work.

[90LX_Notch]

Don't give up on it Ray.  You'll get get it.

-Bob

[Alyn Foundry]

Dear Ray.

I've worn that " T shirt " many times !!

It's probably been mentioned somewhere in the thread, but, what's the bore and stroke measurements, in Imperial please.

Once known, I'll have a ponder. 

Kind regards, Graham.

[Roger B]

Keep at it    It took me around a year to get my vertical engine running as I wanted 

Think about everything that has changed since the first run, can you go back to exactly those conditions? Did anything else change/get disturbed when you repaired the throttle lever?

[RayW]

Hi all and thanks for your words of encouragement. I have been playing with stationary engines, full size and model, ranging from 40cc to 12 1/2 horspepower, since 1985 and have never been beaten yet, so I am sure I will get there in the end. It's just at the moment as fast as I sort out one thing on the Otto, another problem seems to come up.
Graham, the bore is 1" (25mm) and the stroke approx 1 3/8" (36mm).
Roger, unfortunately, I have changed just about everything at one point or another since mending the throttle lever, so I am really starting again from scratch.
Compression is still not good and I am wondering if that is part of the problem. Also, so that it does not show, I have put the glowplug in the cylinder head, right at the bottom of the engine, whereas the plans provide for it to be positioned in the side of the inlet block. One potential problem is that excess oil will fall to the head end of the cylinder and possibly into the recess where the plug sits. I have checked the plug frequently and there has been no evidence so far of that happening.
 

[RayW]

The Otto still remains reluctant to start and run, although today I had a bit more success and managed several short runs, on a couple of occasions being long enough to let me adjust settings while it was running. The governor is working as intended, which is encouraging, but still needs playing with to get it running properly.
Compression had built up quite nicely after the last attempts to get it running, but after todays efforts, I seem to have lost a bit again. I suspect that the gaps in the piston rings may have moved round and aligned themselves, but other than pinning them , which would be almost impossible with such small rings (only 1.5mm wide), I am not sure how I could overcome that problem.

[zeeprogrammer]

although today I had a bit more success and managed several short runs, on a couple of occasions being long enough to let me adjust settings while it was running.

Progress! Come on...that had to feel good. 

[RayW]

Persistence is gradually paying off, with some decent short runs today and easier starting. Made the mistake of getting my wife to see it running, after which it became more and more reluctant to play! Must be a moral there somewhere.
One thing that has become clear is that I need to increase the weight on the governor pendulum arm to give more steady running. Although the governor is hitting and missing correctly, the pendulum arm is too slow to swing back up from the miss position, allowing the engine to slow down too much and lose all its momentum.
The other problem that I need to resolve is that the flywheel is a sloppy fit on the crankshaft, resulting in quite a wobble. The only way that I can see to resolve this is to enlarge the bore, then fit a bush, Loctited and/or held in by screws, then re-bore to correct fit, and re-cut the keyway. Alternatively, I wonder about the practicability of building up the bore with JB weld, then re-boring to a snug fit on the crank. The only problem I can see is that the bore only needs reducing by a few thou and I am not sure that it would be possible to leave such a thin film of JB Weld when re-machining. I suppose that all I can do is give it a try and if it doesn't work, then I can resort to the plug method.

[RayW]

Finally, proof that the Otto does actually run, even though it proved a bit camera shy. Every time I got it running and grabbed the camera, it decided to stop. Eventually, though, I managed to catch it by surprise and got this video. All that's left to do now is make a base and cooling tank.
<a href="https://www.youtube.com/watch?v=3IS74mHnDuY" target="_blank">http://www.youtube.com/watch?v=3IS74mHnDuY</a>

[Ye-Ole Steam Dude]

Watched the video on Youtube and gave you a thumbs up. 

[Dave Otto]

Congrats on a runner Ray, she looks and runs nice!
It appears that you are getting things sorted out.


Dave

[RayW]

Still having problems getting any decent prolonged running from the Otto, in fact, it has decided to play completely dead at the moment, despite having a good low pressure gas supply and a nice bright glow plug. Have checked both valves for leakage and no problem there, so I suspect that I am losing compression past the rings. I have taken the piston out a few times and found that the piston ring gaps have aligned. On a larger piston and rings, I would consider using a pin to stop the rings revolving, but these are really too small to use that method.
I am also getting quite a lot of oil getting past the rings into the head, which must be affecting the combustibility of the gas and air mixture.
Reluctantly, I think the ony way I am gonig to sort this out is by making some new piston rings.
 

[RayW]

Pulled the piston out today ready to make new rings to cure the poor compression and discovered a rather more major problem. The cylinder has two parallel score marks on each side caused by the end of the gudgeon pin. This is obviously where I have been able to hear air escaping past the piston.
On examining the piston, it appears that one end of the pin is protruding by a tiny amount, but enough to cause the grooves. The other end is well recessed below the outside diameter of the piston. The reason that there are grooves on both sides of the cylinder is that I have probably rotated the piston by 180 degrees at some point when removing and replacing it.
The cylinder is securely fixed in the engine and there is no way that I can remove it or replace it, so the only option is to rectify it in situ.
My plan is to re-hone the cylinder using a brake cylinder honing tool, then make new oversize rings for the piston. I will also make a new gudgeon pin with brass ends to avoid a recurrence of the current problem.

Just a final thought - has anyone any experience of filling cylinder grooves with JB weld, then re-honing?

[Ye-Ole Steam Dude]

Hi Ray,

It appears from the photo that the cylinder liner is thick enough to do a mild over bore if you cannot remove the score marks by honing. A new piston could be made along with new rings.

I don't think JB Weld would adhere to the shallow score marks.

It is a great looking engine and surely worth the effort to restore.

Thomas

[RayW]

Hi Thomas,

I agree that a light re-bore would be the ideal option, but it would be pretty difficult with the liner in situ and I am not sure that I have the confidence to tackle that.
My thinking with the JB Weld idea is that if I can get it to adhere in the grooves it would drastically reduce the amount of honing required as it would only be the filled areas that would need reducing. That way, the current piston and rings may well be OK.
Otherwise, it will be a case of gradually increasing the bore by repeated honing until the grooves are eliminated, which could be a long job, then making new rings and piston!