Hi Will,

This is a not an easy question to answer at a distance and could be
any combination of a number of things. I presume we are talking about
a 2½" loco. It would be useful to know which one.

As suggested already, is everything steam tight? Can you hear any
steam escaping from anywhere when you open the regulator but the loco
is still stationary?. You're running on the edge with a 2½" engine and
you can't afford to waste any of the steam.

If you're starting the fire with soaked charcoal, are you waiting
until all the charcoal has burnt away and you've just got coal
burning? Charcoal quickly builds up pressure but won't maintain it
when you are running. I've made that mistake myself!

What coal are you using? If it's a small firebox you may not get
enough heat from just steam coal. Try mixing anthracite with it say
50/50. Some people run on pure anthracite but it burns fast and needs
constant firing. What size coal are you using? If the lumps are too
big, you can't pack enough in the firebox to get the heat. Most people
use lumps from pea size up to bean size. It's worth experimenting to
see which gives the best results. A lot of locos run best with a deep fire
- I run Helen with the coal up to the bottom of the firehole.

Are you getting sufficient blast to keep the fire burning brightly? If
the fire is only burning a dull red, you need to increase the blast by
reducing the diameter of the blast nozzle. The problem I've found with
using a rolling road or just running on blocks is that there is no
load on the loco when it's running and you only get a very soft blast.
The true test is out on the track when the loco is working.

Are you getting sufficient air through the ashpan? Often the ashpan is
badly designed and restricts the airflow through the grate and hence
through the fire.

Is the smokebox sealed properly and airtight. If not, you'll lose the
vacuum and get no air through the fire. The blower may be strong
enough to overcome any leaks but the blast may not be.

Re the water consumption - I couldn't believe how much water these
little locos use when I first started running them! There's very
little water capacity in the boiler so it soon disappears!

Before you start off running, make sure that you've got a good fire
with plenty of coal and a full boiler at blowing off pressure. Then
try and only add water and coal (little and often)when the safety
valves are blowing off. If you have to pump in a lot of cold water or
add a lot of coal in one go, you'll kill the pressure straight away.
And as Keith says, let the engine warm up otherwise the steam will
just condense in the cold cylinders.

Sorry to go on at length but hope some of the above helps,

John

--- In halfinchlivesteamforum@..., "eng10trig" <wjt@...>
wrote:
>
> I am new to running locos, after years of building them. I can get the
> fire up ok, svalves blowing off, but if I turn the blower off and the
> regulator on to move forward I seem to loose all the steam in the
> boiler and the water level goes very low. if I then stop and turn the
> blower back on I can bring the pressure backup. using the tender pump
> to bring the water in. I have tryed running with the blower in but have
> the same results.I then tryed running on blocks of wood so no
> resistance on the wheels, I can get the loco to run for a short while
> but I loose pressure but I can maintain the water.
> Any hints on what I am doing wrong? or anything I may need to change on
> the loco?
> the loco runs well in forward and reverse on air.
>
> Hope someone can help
>
> Will.
>