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Recently we received an Aster Berkshire that was a bit "under powered." Despite making steam it did not have much for power, speed, or for that matter,
To find the problem(s) it was necessary to break in down to the base units: wicks, fuel flow, exhaust, water pump, cylinders, etc.
A major problem was found with the cylinders, with gasket that were deteriorated and the compression o-rings on the steam tee fittings badly deteriorated, causing severe steam and oil leakage. Made quite the mess under the smokebox, oil everywhere. The passages were also badly clogged with sealant, a reduction from 1/8" ports to >1/32" this meant that there was a full cylinder rebuild in store. The oil was very acidic in nature, possibly due to too much tallow and ate through teh silicon and fluoride o rings in the fittings and glands
The pictures tell the story:
Poor condition of gasket and clogged passage ways that was a major cause of the poor power delivery:
Outline of the crossporting....YOU SHOULD NOT SEE THIS! This is due to overzealous use of sealant and is restricting steam flow to the cylinders. If your kit looks like this when looking down into the ports, disassemble the cylinders and correct it.
http://www.mylargescale.com/1stclass/Charles/TR3 services/Berkcylindexportrgasket.JPG
![]()
![]()
Cylinder ports are clogged:
[/b][/b]
![]()
Here is the plug pulled out of the ports
![]()
Combine with the bad "O" rings that allowed loss of steam at the tee fittings :
[/b][/b]
"O" ring comparisons (Bad on left and right, new OEM replacement in center):
![]()
New "O" ring
[/b][/b]
![]()
The cylinder faces were then wet-lapped with 600 and 1000 grit sandpaper. All of the gasket mating surfaces are lapped as well to rid them of any old gasket material or scratches from the removal of old gaskets, some see it as over kill, but it is good practice, ensures a tight seal without a gasket (static friction), and makes the surface level and easier to assemble. All threaded holes were cleared with a tap to be safe.
New gaskets were applied using a thin film of non-rtv sealant (OEM Aster works very well for this, no acetic acid or other heat reactive chemicals to worry about) impregnated into them. The easiest way to do this is to use a dab on your thumb and forefinger and pat the sealant into the gasket, working your way around until the gasket is saturated. carefully lay the gasket on the part and assemble. No excess mess, just wipe the little bit of overlap from the outside of the part and you are done.
Photos of the gasket impregnating technique:
![]()
Here is the gasket laid atop the crossport plate:
![]()
Wiping the overlap from the outside faces:
![]()
On to the track for a steam test:
Drain cocks
![]()
Running well on the straight:
![]()
About two days worth of work and the engine is as good as new. Tomorrow is the shakedown run with a long haul freight.
Back to the shop for the next locomotive, an Accucraft GS4 (demonstrator model) then onto the test track again!
To find the problem(s) it was necessary to break in down to the base units: wicks, fuel flow, exhaust, water pump, cylinders, etc.
A major problem was found with the cylinders, with gasket that were deteriorated and the compression o-rings on the steam tee fittings badly deteriorated, causing severe steam and oil leakage. Made quite the mess under the smokebox, oil everywhere. The passages were also badly clogged with sealant, a reduction from 1/8" ports to >1/32" this meant that there was a full cylinder rebuild in store. The oil was very acidic in nature, possibly due to too much tallow and ate through teh silicon and fluoride o rings in the fittings and glands
The pictures tell the story:
Poor condition of gasket and clogged passage ways that was a major cause of the poor power delivery:
Outline of the crossporting....YOU SHOULD NOT SEE THIS! This is due to overzealous use of sealant and is restricting steam flow to the cylinders. If your kit looks like this when looking down into the ports, disassemble the cylinders and correct it.
http://www.mylargescale.com/1stclass/Charles/TR3 services/Berkcylindexportrgasket.JPG
Cylinder ports are clogged:
[/b][/b]
Here is the plug pulled out of the ports
Combine with the bad "O" rings that allowed loss of steam at the tee fittings :
[/b][/b]
"O" ring comparisons (Bad on left and right, new OEM replacement in center):
New "O" ring
[/b][/b]
The cylinder faces were then wet-lapped with 600 and 1000 grit sandpaper. All of the gasket mating surfaces are lapped as well to rid them of any old gasket material or scratches from the removal of old gaskets, some see it as over kill, but it is good practice, ensures a tight seal without a gasket (static friction), and makes the surface level and easier to assemble. All threaded holes were cleared with a tap to be safe.
New gaskets were applied using a thin film of non-rtv sealant (OEM Aster works very well for this, no acetic acid or other heat reactive chemicals to worry about) impregnated into them. The easiest way to do this is to use a dab on your thumb and forefinger and pat the sealant into the gasket, working your way around until the gasket is saturated. carefully lay the gasket on the part and assemble. No excess mess, just wipe the little bit of overlap from the outside of the part and you are done.
Photos of the gasket impregnating technique:
Here is the gasket laid atop the crossport plate:
Wiping the overlap from the outside faces:
On to the track for a steam test:
Drain cocks
Running well on the straight:
About two days worth of work and the engine is as good as new. Tomorrow is the shakedown run with a long haul freight.
Back to the shop for the next locomotive, an Accucraft GS4 (demonstrator model) then onto the test track again!
![[/b]](http://www.mylargescale.com/1stclass/Charles/TR3%20services/Berkcylinderplugged.JPG){kind=link}
![[/b]](http://www.mylargescale.com/1stclass/Charles/TR3%20services/berksOringsbad.JPG){kind=link}
![[/b]](http://www.mylargescale.com/1stclass/Charles/TR3%20services/berksvalveOringgood.JPG){kind=link}