Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

That can happen if your D-valve is a bit gummed up with old steam oil. I would suggest first trying some light degumming type solvent/lubricant/penetrant such as Break Free (PCL or equivalent) shot down the exhaust port to loosen it up a bit. Heck, even WD 40 would probably do the trick if that is in fact what the problem actually is that you are experiencing. If that doesn't work after a little while, then you are going to need to open up the steam chest to see what's going on in there.

Nice engine BTW, hope that helps and is actually all the problem that you are having.

It might be as simple as the D-Valve falling away from the port face. If this is the case tipping the engine so the steam chest cover is pointing straight up followed by a couple gentle taps with a wood handle or small rubber mallet and give it some air while it is still tilted on it's side.

Best of luck with your very nice looking engine.

Gil

Hi - I had exactly the same problem.
The slider was fitted too precisely and then jammed.
I had to open the slider box and take out the slide and cut off a bit with a file.
Now the D-valve can touch the port face fully.
The Maxwell Hemmens steam engine are very precisely made and they
have no "play" - better to loosen a bit.
Good luck and congrats for this nice one.
Arnold

Gil—I used your suggestion and with 3 taps of my mallet and a little air and off it goes. Now running as a Maxwell Hemmens should