More mamod frustration

R

RMurphy195

Registered
2 Feb 2020
16
Birmingham, UK
So, after a few frustrating things that shouldn't happen, now at last learning how to actually run the brunel MK3.

Finally manged to use the boiler topup valve, but...

After its first use, the loco took much longert to build up pressure! After a bit of experimentation trying to trace a leak, I noticed that if I pt a blob of water into the recess on top of the topup valve - air bubbled through, just like when testing a car tye valve for leaks.

So I took the valve off, checked that I hadn't squirted any debris through it, squirted some water through just to make sure. but still no luck.

Its a strange looking affair - like a hollowed-out plug with a tiny bit of silicon tube blocking the inner exit, works a bit like an old bike Woods valve I guess.

Ideas anyone, short of simply converting the valve into a blanking plug with a dab of solder?

Thanks - Richard.
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
17,867
72
St.Neots Cambridgeshire UK
So, after a few frustrating things that shouldn't happen, now at last learning how to actually run the brunel MK3.

Finally manged to use the boiler topup valve, but...

After its first use, the loco took much longert to build up pressure! After a bit of experimentation trying to trace a leak, I noticed that if I pt a blob of water into the recess on top of the topup valve - air bubbled through, just like when testing a car tye valve for leaks.

So I took the valve off, checked that I hadn't squirted any debris through it, squirted some water through just to make sure. but still no luck.

Its a strange looking affair - like a hollowed-out plug with a tiny bit of silicon tube blocking the inner exit, works a bit like an old bike Woods valve I guess.

Ideas anyone, short of simply converting the valve into a blanking plug with a dab of solder?

Thanks - Richard.
Hm sounds like the Safety Valve so do not do that! Sounds as if you may need a new revised one but be sure. I assume you mean the Valve on top of the boiler?
 
S

Stuart Timms

Registered
2 Jan 2015
42
Bedfordshire
does it have an O-ring, that sits between the top up valve and the stubbing on the engine?
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
17,867
72
St.Neots Cambridgeshire UK
does it have an O-ring, that sits between the top up valve and the stubbing on the engine?
More than likely, if not that could be where you are loosing preasure.
 
P

Paul M

Registered
25 Oct 2016
5,315
57
Royston
It's not the safety valve, that is on the standard water filler. I have never used thetop-up valve. Try changing it for a standard bolt and O ring and see what happens
 
Last edited:
Northsider

Northsider

Registered
3 May 2012
823
It sounds like you have a Goodall valve -the steam pressure forces the silicone tube into the hole, sealing it off. There's not much to go wrong provided the tube is cut to the right length. Might the water be boiling on the top of it?
 
R

RMurphy195

Registered
2 Feb 2020
16
Birmingham, UK
It sounds like you have a Goodall valve -the steam pressure forces the silicone tube into the hole, sealing it off. There's not much to go wrong provided the tube is cut to the right length. Might the water be boiling on the top of it?
I think you are right about the water boiling on top of it. Did find some debris on the burner from a match I used to light it with 'cos my gas lighter packed up, so maybe that's the problem!