Water pump problem

[John LintornParticipant @johnlintorn87585]

Hi all!
Just tested my 5″ Tich 0-4-0 on steam for the first time the other day. She steams up well and runs well. The problem is the axle driven water pump is not able to keep the water level in the boiler up, even with the by-pass valve fully shut!
The pump isnt leaking and I can hear the clack valve working. I thought the problem might be an air lock so I fully opened the by-pass valve for a few minutes and it pumps fine. When I shut it you can hear the engine take the load as the pump begins to work against the boiler pressure. Why wouldn’t it be delivering enough water to keep the level up?
It annoying because as the water level drops so does the pressure so I have to shut the regulator and hand pump the level back up while also trying to keep the boiler pressure up using the blower. I just don’t understand it? Any help will be appreciated.

[John LintornParticipant @johnlintorn87585]

[Bob RodgersonParticipant @bobrodgerson97362]

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 ?

[John BaguleyParticipant @johnbaguley78655]

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

[colin hawesParticipant @colinhawes85982]

My first suspicion would be a leaking clack valve. Colin

[John LintornParticipant @johnlintorn87585]

I suppose the first thing I should do is try and fit a pressure gauge. Then that will show me if the piston is by passing and also if the In let ball of the pump is leaking.
The pump is a 3/8″ ram with a half inch stroke. Do you guys think this is big enough?

[Martin WParticipant @martinw]

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.

[John LintornParticipant @johnlintorn87585]

What do you mean by a leaking clack valve? The water passing back down the line?

[julian atkinsParticipant @julianatkins58923]

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

[John LintornParticipant @johnlintorn87585]

So I tested the inlet check valve by blocking the outlet and running the wheels round by hand. It’s so good that it hydraulically locked the chassis!
Now recently, as i have been running the chassis more, I have noticed the Starboard valve had a blow past. I opened up the valve block and found that the front web between the steam inlet port and exhaust port had no wear. So finding that I assumed that maybe this is why my boiler is loosing so much water and the water pump can’t keep up. What do you guys think? It can only be a thou at most be is that enough to cause the water pump not to be able to keep up?

[Neil WyattModerator @neilwyatt]

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

Neil

[John LintornParticipant @johnlintorn87585]

Well I thought I’d add the latest instalment of the problem solving I’ve been doing on this water problem. I decided to test everything on air. I found air bubbles coming out of the emergency water pump and when the engine is running, water was pumping back into the water tanks from the axle pump!
This is extremely frustrating as I bought the check valves from AJ Reeves so I had put some faith into them and did not expect them to be leaking!!
Of course, my own check valves were no better as I think when I seated the balls, I meerly used a drill and did not ream the seats. Now I have re-seated all the check valves and I’m happy to report the boiler filled up very quickly from both the axle pump and hand pump.
Of course only a steam test will show if this is the sole problem or weather there is a pass on one of the valves/pistons.

[julian atkinsParticipant @julianatkins58923]

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

[John LintornParticipant @johnlintorn87585]

Can you post the link to this thread please?

[WearyParticipant @weary]

Mr Hancock's Clack Valve problems.

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

Regards,

Phil

[John LintornParticipant @johnlintorn87585]

This is disgusting though! How can they sell such faulty steam fittings, so regularly and not be held accountable. Hopefully I have have re-seated mine well enough. Proof will be in the pudding I suppose!

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