# Aster 5MT



## zephyra (Jan 2, 2008)

I was running my 5MT yesterday evening. Started with the cylinder drains open, turned off the blower and forgot that this would kill the draft with the drains open so the engine ground to halt about 1/2 way around the track. As I went over to kick it back into life, I noticed a fire under the engine - alcohol was streaming from the burners onto the track







. I opened up the blower and closed off the alcohol supply and got things back under control reasonably quickly. Only damage was a couple of melted - phew!

Question is whether this means that the outlet on the chicken feed system is a couple of mms too short on this model. If so, is there an easy fix beyond adding a short piece of silicone tubing to the bottom of the outlet.

Robert


----------



## SalM (Jan 2, 2008)

Robert.........my first thought would be to add 2 more strands of wick material to each cup.....I have seen what you described and that was the "fix"............


----------



## seadawg (Jan 2, 2008)

The short silicone tube *IS *the easy fix.


----------



## David Leech (Dec 9, 2008)

Robert, 
I would first of all check that the tank is not allowing air to enter. 
Maybe the cap is not sealing, which will allow the sump to overfill and the wicks to flood? 
1) With the tank out of the tender, and with the fuel control closed, make sure that fuel is not leaking out. 
2) With the fuel control open, place your finger over the 'return' tube and make sure that the fuel stops. 
If these both check out then make sure that the instructions are followed as to how long the silicon tube should be, if indeed it is required. 
All the best, 
David Leech, Delta, Canada


----------



## David Leech (Dec 9, 2008)

p.s. A couple of melted WHAT? 
Wheels, rods, ???? 
Ties, I hope!!! 
Cheers, 
David Leech, Delta, Canada


----------



## zephyra (Jan 2, 2008)

Ties! 

Robert


----------



## dougiel (Jun 3, 2008)

Robert, 

If the draught was not sufficient to keep the fire in its firebox it will wick outside looking for oxygen. When this happens the fire tubes can get very hot very fast. The alcohol will then start to boil and exit the fire tubes and out onto the track. 

If the loco ran OK before with no problem with the fire or alcohol spilling I would think this may be No. 1 culprit. 

Dougie L 
wishing he had got a 5MT when they were available !


----------



## Michael (Jan 6, 2008)

Robert, 

There's still the possibility that the track was not level. 
When the sump is "uphill" and the wicks are "downhill" you may spill spirit even if everything mentioned before is OK. This is more critical with tender locos where the distance between sump and wicks is long. 
It happened to me twice causing fires and burnt ties... 

Michael


----------



## zephyra (Jan 2, 2008)

Posted By Michael on 03 Jul 2013 05:34 AM 
Robert, 

There's still the possibility that the track was not level. 
When the sump is "uphill" and the wicks are "downhill" you may spill spirit even if everything mentioned before is OK. This is more critical with tender locos where the distance between sump and wicks is long. 
It happened to me twice causing fires and burnt ties... 

Michael 
As it happens the track isn't as level as I would like. It was built for me very recently by a local contractor who is also a steam enthusiast. I think he might used unseasoned timber so I am seeing some warping in the beams which is producing slight undulations. Everything looks great when you look down on the track but at eye level you see that it isn't completely flat.

Having said that, I don't think this is the problem here. I think it is simply lack of draft (draught) by having the cylinder drains open. The drains on this machine are controlled by a reach rod that goes back to the cab and it very easy to push them open while adjusting the throttle. 

Robert


----------



## David Leech (Dec 9, 2008)

A couple of things are bothering me with some suggestions here. 
I don't pretend to be an expert, but I have been running alcohol live steam for a while. 
Dougie, my experience with a lack of draught is that the flames will indeed flop around, and depending on the design of the firebox will come out and up the side of the loco, but I don't think that the flames are not particularly hot at this point which is why you don't have to worry about running dry. 
I have never seen what you describe with boiling alcohol flowing out of the burner tube when this happens. 
Next time I am running, I will attempt to duplicate it. How long does it take? 
Michael, I don't know which Aster loco that your problem happened, but 'most' burner tubes are probably what 3/4" high, and IF the sump and chicken feed are working properly, they would only be perhaps half full, and probably less. 
Yes, the wicks will 'wick' up the fuel, but not really as a liquid. 
So, if the distance of the tender to the burner tubes is 8 or 10 inches, it would need probably a 10º downhill slope for the raw fuel to get to the top of the wick tubes. 
Since Roberts track is reasonably flat, I can't see this happening in this case. 
Robert, lack of draught will cause flame to exit the firebox, although I am not familiar with the 5MT design, but I can't see how it would cause the fuel leak that you speak of. 
I run my Royal Hudson with drains open, but there is still plenty of exhaust still going up the stack. 
I still think that it was air getting into the fuel tank through the cap. 
Try it again sometime and let us know. 
All the best, 
David Leech, Delta, Canada


----------



## Michael (Jan 6, 2008)

David wrote:

_.... I don't know which Aster loco that your problem happened, but 'most' burner tubes are probably what 3/4" high, and IF the sump and chicken feed are working properly, they would only be perhaps half full, and probably less. 
Yes, the wicks will 'wick' up the fuel, but not really as a liquid. 
So, if the distance of the tender to the burner tubes is 8 or 10 inches, it would need probably a 10º downhill slope for the raw fuel to get to the top of the wick tubes. 
_ 
David, 

I am sorry that you feel bothered, however, since I have also been running spirit fired locos for more than 20 years, I am just sharing my experience.
Taking your figures: with a 3/4" burner tube half full it takes just 3/8" to the brim. Now with a length of 10" between sump and the most distant wick that yields a slope of 3/8/10 = 4%.
But don't think of real slopes or grades only. On undulating track it suffices if the loco sits in a "hole" that's just 3/8" or 10mm lower than the tender. That's not too unlikely.
It has happened to me with an Accucraft GS4 and an Aster S2.
By the way - I think the spirit level in the tubes should not be less than half full and wicks not too densely packed. That's what the Swiss importer of Aster once recommended for good performance and that's what I always check with my locos.
Again - just my experience, however, I am happy to learn from others.

Regards
Michael


----------



## AsterUK (Jan 2, 2008)

Robert

I have sent you a PM which goes into details. 

However, I guess you may have swapped the fuel tank from your Bulleid pacific with your 5MT - they are interchangeable. A curious feature with the Bulleid was the sudden leaks of fuel because the breather tube in the tank has spilt. Reasons for this is still unknown although the tanks supplied on later models have been free of this issue.

It is quite easy to change the breather by melting the soft solder and replacing with a length of K&S thin brass tube 1/4 inch dia.

Let me know how you get on with that.

Andrew

Aster UK


----------



## David Leech (Dec 9, 2008)

Posted By Michael on 04 Jul 2013 12:48 AM 

Again - just my experience, however, I am happy to learn from others.

Regards
Michael

Hi Michael,
Thanks for sharing.
I will try and make sure that I don't run on tracks with dips THAT bad.
All the best,
David Leech, Delta, Canada


----------



## zephyra (Jan 2, 2008)

Posted By AsterUK on 04 Jul 2013 07:07 AM 
Robert

I have sent you a PM which goes into details. 

However, I guess you may have swapped the fuel tank from your Bulleid pacific with your 5MT - they are interchangeable. A curious feature with the Bulleid was the sudden leaks of fuel because the breather tube in the tank has spilt. Reasons for this is still unknown although the tanks supplied on later models have been free of this issue.

It is quite easy to change the breather by melting the soft solder and replacing with a length of K&S thin brass tube 1/4 inch dia.

Let me know how you get on with that.

Andrew

Aster UK

Andrew, thanks for the input. I didn't know that the Bulleid and 5MT fuel tanks were interchangeable.....


I don't think the problem is the breather tube. I added a small piece of silicone tube to the end of the feed pipe in the chicken feed system and all looks to be well. I ran the machine on rollers for about 30 minutes and deliberately killed the draft by opening the cylinder drains and stopping the motion. No sign of any over-spill from the burners. I put the whole thing at a 5% slope and still no issues. 

Robert


----------



## AsterUK (Jan 2, 2008)

Hi Robert

The split in the breather tube if it occurs, is inside the tank and not visible, that is the annoying aspect. However the outcome of this malfunction is a flare-up exactly as you describe. 

You can check the tank's integrity by filling with fuel, open the valve and see if fuel is stopped when you put your finger over the end of the breather tube. If it stops and starts then no worries. If applying your finger has no effect on fuel flow then the breather has split inside the tank.

Andrew


----------



## zephyra (Jan 2, 2008)

Andrew, thanks - I checked as you suggested - all is fine. 

Robert


----------



## dougiel (Jun 3, 2008)

David, 

Not seen the meths overflowing on an Aster as I have only just got into G1. 

It has happened though on two 16mm narrow gauge locomotives I own. Both Archangel with a meths burner and chicken feed as Aster but in the loco rather than a tender. When it happened once the unseen flames were extinguished the flow of meths stopped. I can only presume that there was enough heat in the tubes and sump to expand the liquid enough to force it out of the buner tubes. 

Dougie L


----------



## David Leech (Dec 9, 2008)

Hi Dougie, 
Tank engines where the fuel tank and burner are all in one, or at least joined by metal, do suffer from this. 
As everything heats up the alcohol will expand, normally in the tank which often have an overflow, so the excess fuel will dribble out, hopefully not to be ignited. 
My guess is that yours do not have an overflow, which of course will cause 'burning' fuel to leak from the wick tubes. 
Best not to fill the fuel tank to it's maximum, and leave some expansion room. 
All the best, 
David Leech, Delta, Canada


----------

