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Q&A's > Engines - General
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3. ENGINES – GENERAL

Q. Why do we advise against the use of compressed air for running an engine?

A. We sell “Steam” engines – not “Compressed Air” engines! All engines require lubrication of the internal components while running. Model steam engines provide this lubrication using a simple device called a “displacement lubricator” that does not work with compressed air (see next question). We know of one client who has several engines run by an air compressor through a well-designed oil injection system. By all means use compressed air, but make sure you maintain the lubrication of the internals of the engine. WE WILL NOT ACCEPT warranty claims for engines that show excessive wear through inadequate lubrication.
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Q. How does a displacement lubricator work?

A. The word “displacement” is in the description of the lubricator because of the way it works.
With a full lubricator the steam is directed across the top of the oil column, picking up a small amount of oil and in doing so a little amount of steam condenses to water. This drops to the bottom of the oil column, pushing the top of the oil column up to replenish the oil supply to the steam flow.
The fitting at the bottom of the lubricator allows you to drain off the water before refilling with oil.
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Q. What is “steam oil” and why is it needed?

A. This is a very good article that answers this question generally.
http://www.southernsteamtrains.com/misc/steam-oil-petitjean.htm
We use and supply the lightest grade of steam oil available in Australia – International Grade 469
Manufacturers of steam oil are usually reluctant to sell less than 20 liter containers, sometimes more. That is more than you will use in a lifetime.
We are happy to supply internationally (P/N 8321) but suggest looking for a local steam club that buys the big containers and sells it off to members in sensible sized bottles.
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Q. What other lubrication is required?

A. All external parts that rub against another surface should be lightly dosed with a light machine oil after every run. The MSM slide valve engines have small lubricator cups to help direct the oil to some, but not all, critical parts.
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Q. Do engines need to be “run in”?

A. New MSM engines should not need "running in" before they achieve free running. If there is stiffness that is "firm" but otherwise smooth, proceed to powering the engine and allow it run for about three boiler loads of operation.
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  1. Engine is stiff or won't turn over at all.

A. When cold the engine should turn freely but firmly under finger pressure on the flywheel.
There several possible causes and corrective actions:

- Oil used during engine assembly to lubricate the moving parts can “dry out” over time. Fix by applying fresh light machine oil while turning the engine over by hand.

- Uneven tension on engine mounting screws that could be twisting the engine frame causing the crankshaft to bind.


- Excessive packing or tightening of connecting rod stuffing boxes.


- Incorrect re-assembly of crankshaft bearings & crosshead occurring when maintaining the engine


- Misaligned propeller shaft where fitted.

-Incorrect use of the bearing alignment shaft supplied with the kit (Avon self-assembly kit only)
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Q. Engine runs freely but does not generate expected power

A. Check valve timing (slide valve engines only)
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