Water gauge issue

Hi there,

I’m currently running a Maxitrak 3/4inch allchin and I’m having issues with an unreliable water gauge. When I’m running the traction engine I seem to be getting air inside the gauge causing the level to be inaccurate. The problem seems to be when running it on slight inclines, where perhaps air is entering the gauge. I’ve checked for blockages and can’t see any. It could just be a limitation of the model, any ideas? The glass doesn’t seem to be obstructing the inlet or outlet pipes from the boiler.

thanks Sam

Sam,

I see this sliding down the list, unanswered. I don't have a Maxitrak Allchin or experience of, I do have a Dixie loco though and have worked on a 3" Maxitrak Avelling. Standard gauge glasses on those worked but were rather a small diameter so didn't work as well as they might have.

Not sure exactly what you mean in your question? Are you saying you get a "bubble" under the expected level of the water or does the water disappear from the glass and not come back? What happens if you open the blow down, does the water disappear and then bounce straight back up when you close it? That would be the normal scenario if all passages are clear. You say you have checked for blockages and can't see any? Have you taken the fittings off the boiler and made sure there is no scale built up in either the fittings or the tappings in the boiler? Have you blown through both top and bottom fittings and made sure there is no restrictions?

With a proper 3 cock glass you would close both cocks to the boiler and open the blowdown and drain the glass to make sure both valves to pressure close off, then with the drain open open the water (lower cock) and make sure you have a good flow, you can tell by the sound what the flow is like. Then close the water valve and open the steam valve and make sure you have a good flow of steam, this will sound markedly different, higher in pitch. Then close the steam valve, close the blow down and open the water, water should go right to the top of the glass, then open the steam valve and the water should drop to the correct level. Finally open and close the drain and see the water bob down and then back up the glass. Unfortunately I suspect you have only a blow down so you can only do the last test. If the water does not disappear and return quickly then I would suggest one of the fittings to the boiler is blocked. You only have steam or water to play with when its in steam, no air!

Worth noting an incline (or decline) can have quite an effect on water reading. A trick from the old time enginemen when going down hill and the water disappeared from the bottom nut was to haul back on the reverser to slow the engine to get the water surging back and forth in the boiler to give an idea of the real level. One "mistake" of inexperienced drivers when the water reading was fine on the level is to top the boiler up when going down hill to bring it back up the glass (often causing priming) and then when they start up the hill the other side of the down grade there is a lack of steam space, lose pressure and more priming! Always good to know where exactly the water level is when on the bottom nut of the gauge in relation to the firebox crown, then you know what your margin is and when to panic!!

Good luck,

Paul.

Hi there,

thank you very much for taking the time to reply to me.

I get both of the above issues, bubble in the middle of the water and loss of water from the gauge, I have also encountered a full gauge even though the water level is truly half full. Unfortunately there isn’t a blow down on the gauge so there’s nothing I can really do.

I took the whole assembly apart today and checked for blockages and couldn’t find any. I did see a post elsewhere that said a piece of wire in the glass could stop the bubbles forming by reducing surface tension. I did this today.

I haven’t steamed it up yet so I’m not sure what effect it will have. I think the design is the issue. The piping doesn’t go straight into the boiler at the top nut, it goes at 90 degrees to another fitting that has a hollow bolt that then goes down into the boiler at the top. I reckon water/air is getting stuck in that bolt (after being sloshed about on bumpy ish ground) and causing the level to show incorrectly. My next step is to drill out the bolt diameter a little more I think.

thanks again

Sam

Hmm sounds a bit "unconventional" to me. Might not be the best plan to drill out the banjo bolt lest you make it too weak? Maybe post some pictures? Have you tried talking to mssrs Probyn at Maxitrak to see if they have any words of wisdom?

Paul.

I can't see the use of a banjo steam fitting would cause problems. If anything it should mean no water entering the top or the gauge, thanks to the extra height, but anyway blowing the glass down should clear any that might be there.

You don't say how long you have run this engine or if you live in a hard water area, but this sort of problem does suggests a blockage. If not in the gauge-glass and its associated fittings and boiler-bushes, then depending on how much the engine has been used and with what water, I would start worrying if scale or dirt is accumulating in the back-head water-space and affecting water-circulation.

I can't see this is a design problem, and I would not try drilling out fittings. As Paul says, that may merely weaken them.

Sounds like fitting a blowdown cock on the gauge would be a help. Isnt it dangerous to operate a boiler without one? You wouldnt even consider it on a full sized job. Or is it common model practice to go without ?

Edited By Hopper on 16/06/2020 02:31:01

Hi guys,

I have contacted Maxitrak but are waiting for a reply. The model is new (only a few weeks old) it’s only been steamed up 5 times using distilled water, so there shouldn’t be any scale build up. It looks like it May have to go back to them for a look over.

thanks

Sam

It's certainly not a good idea to operate without a blow down on the glass and it's unlikely a competent boiler tester would issue a certificate on a boiler above 3 bar litres without one but this boiler is so small I imagine it falls in the less than 3 bar litres category. The rules for less than 3 bar litres are rather loose from memory not even having a pressure gauge as mandatory!

Paul.