Water pump problem

I would suggest you double check that there isn't wear on the pump piston that may be bypassing water. Is there any way you can disconnect the feed line from the pump, fit a pressure gauge and a valve on a tee. Run the engine with the valve fully open then gently throttle the pump output to check the delivery pressure ?

The inlet ball valve of the pump may be leaking under pressure and allowing some of the water to go back into the tanks instead of into the boiler. It's also possible that the pump is simply not big enough to maintain the water level.

John

My first suspicion would be a leaking clack valve. Colin

It would be well worth while looking at the clack/check valves ,You've only got to look at the trouble Ron Hancock had with clack/check valves leaking on his Black 5 these were all 'NEW Commercial items and they all leaked. It was only after a great deal of help from a member of this forum he eventually managed to overcome the problems and is now happily steaming. Good luck and I hope you solve the problem quickly.

Hi John,

The axle pump should have a ball seating above and below the ram. In effect they are 2 check valves as part of the pump body.

I always test check valves quite rigorously.

As John Baguley suggests, yours may not be seating properly. It is also possible the boiler check valve is not seating properly (the water in the side tanks will heat up quite a lot if this happens).

It would not take much for the valves not to seat on a new loco - a bit of swarf or muck.

Another possibility (which is quite common) is for the bottom axlepump check valve to 'stick' especially if no 'U' bend incorporated. This isnt the case in your's as you have observed the bypass flow.

There may also be some restriction somewhere? Perhaps a pipe bent and kinked, or a nipple onto a pipe on the delivery side partly blocked with silver solder? Or perhaps there is a restiction in the water supply to the axlepump somewhere.

The Tich axlepump, if made to the drawings has not been commented upon, to the best of my knowledge, as being other than very effective.

I would disconnect the boiler feed pipe from the boiler check valve, and run the chassis on air with the bypass closed and trying to stop the flow from the pipe. The water should squirt a considerable distance.

Cheers,

Julian

Could be, once there's a gap the stem pressure might cause the valve to lift even more when running.

Neil

Hi John,

You are not the only one to find that some commercial check valves sold by the trade are poorly made - see Ron Hancock's posts re his Black 5.

Cheers,

Julian

Mr Hancock's Clack Valve problems.

If link doesn't work simply search site for Clack Valves as topic heading.

Regards,

Phil