When you first open the regulator the cylinders will be cold and much of the steam will condense, hence water and steam from the chimney, quite normal. As the cylinders warm up only steam will be emitted, if water continues to flow you may have overfilled the boiler, eventually this should stop.

Andy

You mention the drain cocks starting to blow steam, and then refer to opening the regulator. The cocks shouldn’t be blowing with the regulator shut, is it leaking?

Not a steam man, but bear in mind that when full size steam locos start away, the cylinder cocks are open, and left open, for some time.

This prevents condensation in the cylinders causing damage to cylinder, pistons and motion work.

May i suggest that you are suffering because the cocks are closed too soon, and condensation that should be ejected via the cocks is being sent up the chimney?

Try opening the cocks before opening the regulator, and leaving them open for three or four revolutions of the driving wheels. Life might be a little cleaner!

Howard