Marcher twin cylinder marine steam

[Team ricky]

Thanks for adding your experience

Today I made the intake manifold and banjo bolts and banjos….

Too tempted by a compressed air run I tried!

It’s a fail as of now as it won’t run, gave it a good spin on the flywheel, adjusted timing slowly all the way to run in the opposite direction and never got more than 3 un aided turns ! Won’t even try to self start

I have No gaskets under the the lower cylinder covers and a little soapy water shows big leaks so probably a factor…. I will fit gasket’s and test but I’m not hopeful…..

Down the steam rabbit hole me thinks!!!

[Team ricky]

Here’s a short video showing where all the steam’s going!!

Effectively the pressure is just venting to exhaust

I re-made both piston valve to give 0.2 mm extra ‘Land’ over the ports thinking if the pressure is overlapping some, Does not seem any better and then the lack of eccentric travel starts to show up as the port not being open even with the piston still needing to travel down the bore….

Which leads onto the following issues I’ve found:

1) the crankshaft is scrap ( I didn’t make it ) - only gives 7mm total stroke as a pose to 11mm
Ordered material to make a new one.

2) The piston valves are made from ground stainless but slip in too easily in my opinion…
I’ve ordered 5mm silver steel to re-make another pair provided the material is tight fit - If no I’ll make the material to the tolerance needed and run them in …

3) replace the vitron piston rings just as a matter of course
I have material in stock and should eliminate any blow by

Beyond that lot I’m not sure what to do !!

The steam I think can’t be getting by the pistons at the rate in the video

I think the main issue is the piston valve tolerance to bore but we will see!

Lastly I probably will re-make the eccentric’s to give a 3/4 open condition vs less than half port open condition- even more important when I have the correct stroke as at present the port shuts as the piston is still travelling down say and that’s on 4mm reduced stroke!

[MJM460]

Hi Ricky, frustrating when an engine does not run, but most issues are solvable, the trick is to work out which issue is at the root of the problem.  I have a couple of thoughts which may help, help to avoid time wasting on unlikely issues anyway.

First, I would keep experimenting on air, it’s so quick to start and stop the compressor, and no waiting for heat up and cool down that makes each steam test more time consuming.  If it won’t run on air, it won’t run on steam.  On the other hand if it runs on air, steam is then straightforward.

It’s desirable to make the new crankshaft for the sake of efficiency, but I don’t think it will stop the engine running.  It will use more steam than necessary, and produce less power with the short stroke, but should run, as you are not really giving it any load.

The valve is normally made a little longer than just bridging the ports, this is called lead, and requires the timing to be adjusted so the opening starts very close to the end of the piston stroke.  This means the port closes before the piston reaches the bottom as you have noted, but that is normal.  The engine continues to do work to the end of the stroke after the valve closes as the air or steam expands.  No real difference in this respect.

The fact that the ports do not open fully also should not stop the engine running.  Again, it will affect the maximum power from the engine, when it is fully loaded, but again, should not stop the engine running, even if it requires more pressure than you would like for unloaded running.  When you have it running, you can try making an eccentric with bigger throw.

I have found a little leakage past the piston can be tolerated, but you don’t want the rings making the piston too tight.  Just check that it is not really loose.

I have not yet tried a piston valve, but the piston valve fit would be high on my list of suspects, I think engines are more sensitive to leakage past the valve than past the piston as this leakage steam does not do any work.  I have had the occasional issue with slide valves not seating correctly, and the resulting leakage definitely stops the engine from running.  So that is where I would start looking.  No doubt, others with more experience of piston valves will chime in here.  If you hold the flywheel and turn the engine to a little before bottom dead centre, where the ports should be closed, then the valve leakage will be visible and you will get a good idea if there is too muck leakage.

And of course, the valve travel needs to be set so the movement is symmetrical for the up and down ports.  And best to set the piston rod length so the piston travel is also symmetrical about the centre of the cylinder.

It may be worth removing the pin from the eccentric strap so you can move the valve by hand.  Moving the valve should move the piston up and down unless the leakage is excessive.  Then reconnect and reset the timing.

Unfortunately my iPad doesn’t want to run your movie, so I haven’t been able to view that.

There may be several factors at the same time, but you should see some improvement with each thing you fix.

I hope those comments help you find the key issues.  We are all barracking for you to get it running.  It’s usually small things at this stage.

MJM460

[crueby]

Hard to tell from the video where its blowing out the steam, though it looks like it might be at the bottom of the block, piston rod seals or valve rods?
I like to do leak checks with compressed air, a lot easier and safer on the fingers! At a low pressure, I'll use either bits of tissue to track them down, or water on a swab, usually shows the leak spots very quickly for ones on the outside at gaskets/glands/pipes/etc. Piston/spool valves are always tricky things, a very minor gap will blow a lot of pressure by. If you can tighten up the gaps enough to get rid of most of the blow by, it will run fine. Some leakage is not a problem, and any full-size engine I've seen running has some around the piston/valve rods. What I see in the video is too much though, but should be fix-able.
As MJM said, the piston valve is a likely suspect, either too poor a fit and blowing around it, or if either the center gap is too wide and bridging the ports, or the overall length is too short and not closing ports like it should. Again, putting it on compressed air and turning the crank over slow by hand should identify the issue pretty quickly.

[Team ricky]

Hi,

Thanks for your support and time

I went through a similar thought process re- finding the problem by changing ins thing at a time with the piston valve suspect number one !

I had a happy thought to nickel plate the piston valves until they won’t fit then polish them carefully and get a slip fit to run in !

The video if you get to see it shows pretty much all the steam bypassing and coming out of the exhaust ports at an alarming rate !!

I’ll try the plating first
New piston rings second
Re make eccentrics to give 3/4 port thro
Make a crank if I see a good improvement

I think you are right in saying I will get it running as it’s possible to eliminate issues one by one  ☝️

[Team ricky]

Here’s one valve coated …

I have since polished it and it comes up very well too tight to fit now which is perfect…. I’ll slowly polish down to a fit!

[crueby]

Now thats a neat idea! Never thought of that one, that saves a lot of work making a whole new one.   

 

[Kim]

Who says you can't put metal back on!  Ha!  You proved them wrong there     

Kim
 

[john mills]

I would not expect the piston valve to completely seal it will have clearance so it can move  .have look at full size engines full size sissan engine
when stopped quit a bit of steam will go out the exhaust they have a plain piston valve with clearance so will leak but when running work.
we would just like it to be minimal.
john

[Team ricky]

Yes there is definitely going to be some pressure loss due to design!

The short video was at 50psi and it won’t run…. It sure looks like most of the steam was bypassing straight to exhaust…. Just have to fully track that down …. The one valve I’ve plated I polished and fitted and is much harder to blow by now , Just need to make a second and repeat the process and see what happens

[Team ricky]

Good news on the replacement silver steel stock for the valves …

I’ve made one and pressure tested it in its bore and it’s a damm sight better! Not completely sealed as you’d expect but hard to get volumes past it ! Probably 3x better I’d say

[crueby]

Thats great!!

[Team ricky]

Here’s a short video just after putting better fitting piston valve in …

I’ve ordered some Teflon tube to see if I can sleeve the piston valve bores, It might not work so I went with I’d that will slip in the bores and I’ll make under size piston valves 

At least I know where to put time into the project! And I’m only 30/40% off good running

[crueby]

Thats MUCH better!!

[Kim]

Looks like it's running pretty nicely to me! 
Kim