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displacement lubricator

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John gallo20/06/2016 14:39:48
26 forum posts

I am finally getting to steaming up my recently completed Stuart beam engine. To any one who has used one of Stuart's displacement lubricators I have a question.

What is the proper level to fill it with steam oil? I notice that there is a valve tube near the top. Should that be covered? Thanks in advance, John.

JasonB20/06/2016 16:18:50
17856 forum posts
1954 photos
1 articles

My stuart catalogue says "do not fill above the cross bar"

If you fill above this you will just get oil run out into the steam pipe, too far below and you won't get any oil to the engine until the condensate has brought the oil level upto teh oitlet.

Bryan Bushranger Red14/06/2017 10:29:25
5 forum posts

How does the displacement lubricator continue to work once the lubricator body gets too hot to allow condensation of the steam which enters it?

I have made a lubricator and find that it works well for the first 10 to 15 minutes but after that can stop dispensing oil completely. Do you need to be continually adjusting the needle valve during operation? I am only experimenting at the moment with a small PM # 7 engine. I am happy to be getting some oil into the cylinders as opposed to none.

Also, is there anyone who has tried to make their own SCO? As here in Australia I think it'd be easier to find fresh rocking horse faeces. Currently I am using a mix of about 80/20 of sewing machine oil and lanolin with a small amount of tallow melted into the mix.

I think my engine runs at very low pressure, as I can actually make it run by blowing through the inlet. But not for long though lol, as I begin to see many stars very quickly. Any help or advice would be greatly appreciated and thanks in advance.

Regards... Bryan

Neil Wyatt14/06/2017 17:15:45
17729 forum posts
697 photos
77 articles

Hello Bryan,

Welcome to the forum. What is the consistency of your mixture? Sewing machine oil is like water, but steam oil is thick.


Bryan Bushranger Red14/06/2017 23:13:28
5 forum posts

Hi Neil, thank you for the welcome,

Yes the machine oil is quite light and the Lanolin doesn't really add the viscosity. I have never seen true SCO as I have only just begun.. well only been trying to make model steam engines for about 6 months now. I think I went for machine oil for the ease of clean up. At the moment I am trying to "Nut out" some sort of condenser/catcher for the exhausted steam. I will admit to cutting short in a number of area's on the engine due to my limited experience on a lathe and therefore lack of skill. So should I try for a heavier oil then? At the moment I am happy to have a little lube going into the engine, anything's got to be better than nothing?

Any advice from anyone is greatly appreciated, as my knowledge is very limited.

Regards Bryan.

Pero15/06/2017 04:02:08
105 forum posts

Hello Bryan

Steam oil is available in Australia from Miniature Steam. I have some but haven't used it in anger as yet. They do send it by post/courier - quite successfully as I am located in Western Australia.

There may be other suppliers about but this is the one I know of through buying their engine kits - superb castings by the way.

Welcome aboard, Pero

Bryan Bushranger Red15/06/2017 04:12:13
5 forum posts

Thank you Pero,

I'll have a look at their site. But I must be careful that my enthusiasm doesn't over ride my ability and skill. Although having said that, I did buy this kit for my son's 16th and I am starting to become a little worried he'll never get it lol.

​Thanks for the help.

Regards Bryan

Bryan Bushranger Red26/06/2017 07:40:12
5 forum posts

Well I finally received my "Steam Cylinder Oil" and initially I was amazed at it's visual characteristics. It's quite unique, thick and has a sticky almost spider web consistency. Of course an immediate run was required to assess the difference to what I had been using. When I started using my home made concoction in my newly made lubricator there was a marked difference in the noise my engine made along with an expected improvement of slow run capability. I even had to make a new crank bearing as the noise it was making was quite notable.
​But now running with the correct oil the difference in the noise made and smoother running is even more improved. Initially I think I had a little too much oil running in, possibly because I'd over filled the lubricator slightly. It was difficult to get the SCO to run as it was about 5 degrees Celsius. Of course once the steam began to flow this was reversed very quickly.
By using my .... "Modified" picnic burner I am able to get my small engine to run at about 75RPM, and I could not be happier.

Thanks again Pero and Neil.

Regards to all, Bryan

Henry Artist26/06/2017 21:29:32
68 forum posts
46 photos

Good to hear you have your engine running happily now. You may like to read this article - **LINK**

As you have no doubt realised a Displacement Lubricator is so called because steam condenses in it and as oil floats on water it displaces the oil forcing it into the steam line and thus it is carried to the engine. But that's not the only thing that is going on.

Can you say "water hammer"?

The pressure in the steam line (the pipe that goes from the boiler to the engine) is not constant. No sir, it is not. While the engine is running it fluctuates slightly. As a steam port opens and the piston begins moving into the cylinder the pressure momentarily drops. When the steam port closes a pressure wave travels back up the steam line (at the speed of sound for the medium through which it is travelling). Go look up "water hammer" for more information.

This is why it is a good idea to locate a displacement lubricator as close to the engine as possible where the effect is greatest.

Bryan Bushranger Red26/06/2017 23:19:28
5 forum posts

Hi Henry, I have actually read that article before.. But my reasoning for trying something I could make was because of the fact I am somewhat isolated, and even when I do go into town asking for steam oil is like asking for a long weight for a pull through.

Initially I was happy simply to have some sort of lubricant running through my engine, far better something rather than nothing. And I am happy to have found a place where I can actually get SCO, thanks to Pero. The difference is as remarkable as running from dry to my sewing machine oil concoction so obviously way better.

Yes I have noticed the "Water Hammer" characteristic, as I am only using aquarium air line which is almost clear. I can see all the pulsing and the movement of the SCO through the line between the engine and the lubricator. Even if I cannot see the lubricant in the line it's easy to check simply by rolling the tubing between my fingers for a moment. If it is completely dry of lubricant it simply will not roll. I will keep in mind the requirement of mounting the lubricator as close to the engine as I can, and when I am all sorted I'll replace the silicone tubing with copper lines.

​Thanks for the info,



Brian John30/06/2019 02:07:45
1455 forum posts
579 photos

1. How often should a displacement lubricator be cleaned ie. open the bottom plug and drop everything out then replace with fresh steam oil ? (I am running small stationary steam engines from PM Research and Bengs Modelbau.)

2. I have noticed that there is water that accumulates in the bottom of the lubricator. Should this be dropped out after each run ? Up until now I have been leaving it there with no problems.

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