The Unofficial Mamod and Other Steam Forum

MooseMan · Posted: Tue May 20, 2008 6:49 pm Post subject:

As far as I know all Bowman safety valves (I have 9) unscrew at the bottom end, but sometimes they stick - in that case a bit of heat invariably frees them up....you just need to break the lime bond that will have formed on the threads.

I missed Pete's original post.....the valve on the left is a boat valve, it dooesn't have the stickyout bit (technical term

) because that would foul the boiler shroud.
_________________
Stands the glass half empty,
Or stands the glass half full?
Blast your Buddhist mantra, man,
I'll take another pull.

johnreid · Posted: Tue May 20, 2008 7:09 pm Post subject:

It is possible that mine isnt authentic then I guess. No evidence of threads even, However like I said, the Safety Valve on my M158 is threaded and after a soaking in Vinegar it unscrews with ease.
_________________
Your life is an occasion...Rise to it

steamgranny · Posted: Tue May 20, 2008 7:33 pm Post subject:

OK lads, I've answered the question myself

Had a good poke around & under the crud detected a screw thread at top end, just as MM suggested.
Therefore confirm that this type of Bowman SV (& I'm sure it's a genuine one, John) unscrews at top. See below:

johnreid · Posted: Tue May 20, 2008 7:48 pm Post subject:

Well, it looks like mine is going to spend some time in the Vinegar now.
_________________
Your life is an occasion...Rise to it

flywheel61 · Posted: Tue May 20, 2008 8:31 pm Post subject:

SG, if it won't come undone, see if you can get several circlips small enough not to interfere with the SV thread but big enough to go over the SV spring shaft. Then add them, one by one, betweeen the 'nut' on the end of the shaft and the spring, until you have the desired tension. May save you a bit of money and you'll be using the original SV.

Cheers

Chris
_________________

Mamod mania strikes again

Atticman · Posted: Tue May 20, 2008 8:42 pm Post subject:

Thanks for that SG, the strange thing is that I was steaming my M158 on the weekend and noticed that its SV is the same as yours. Will have a ferret around and see but am pretty sure that the others are all screw at the bottom ones.

steamgranny · Posted: Tue May 20, 2008 8:48 pm Post subject:

mc_mc · Posted: Tue May 20, 2008 9:24 pm Post subject:

I've tried stretching the middle of spring whilst it's still installed and was successful (I just gripped either end of the spring coils and pulled the middle ones out a bit with my fingers). That wasn't on a bowman valve though but the principle is the same, you haven't got much to lose really.

I also managed to "wind on" a new spring on to another SV post with out disassembling anything too. (Most of the modern valves don't come apart easily). Getting the first coil round the post is the trickiest bit but once one part is wrapped round the next follows easily.

Atticman · Posted: Tue May 20, 2008 9:39 pm Post subject:

johnreid · Posted: Tue May 20, 2008 10:05 pm Post subject:

Soaked it in Vinegar, no luck, soaked it in heated Liquid Wrench ( penetrating oil ) and Eureka! it unscrewed!!!

I believe that I will place a Teflon washer between the two top parts till I find a suitable spring. I bet my M135 will run twice a fast now.
_________________
Your life is an occasion...Rise to it

steamgranny · Posted: Tue May 20, 2008 10:25 pm Post subject:

Les · Posted: Tue May 20, 2008 10:27 pm Post subject:

Glad to hear you have both sorted out your safety valves.

_________________
Les - Old age isn't so bad when you consider the alternatives.

www.freewebs.com/lesmarsh