Fitting a standard o ring to a mamod/mss boiler sight glass

A very popular starting point for Live Steam. With their low cost comes a number of problems which can be discussed here
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Lner fan Sam
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Fitting a standard o ring to a mamod/mss boiler sight glass

Post by Lner fan Sam » Wed Jul 17, 2013 7:08 pm

Hi all,

I have steam tested my mamod and found that there was a steam leak on the sight glass. I now have a replacment o ring and I am having trouble getting it to stay in the recess as it is not a oval shape.

Does anyone have any tips for fitting this to the sight glass?

Thanks in advance.
my first live steam engine build thread:
http://gardenrails.myfreeforum.org/about6685.html

Sam Wake

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Chris Cairns
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Post by Chris Cairns » Wed Jul 17, 2013 7:22 pm

Sam,

Lightly coat it with oil or washing up liquid. It should fit around the boiler cut out (I tested it on my workshop Mamod boiler before I sent it). Put the sight glass plastic on top of the 'O' ring centrally. Hold the plastic in place with one finger at the bottom and slide your brass back plate down from the top till it meets your finger. Put something like a flat edge screwdriver or small paint brush end through the slot in the brass back plate to continuing holding the sight glass plastic in place whilst you line up the holes in the brass back plate with the boiler threaded inserts. Do up your screws snug but not over-tight. Job done.

That 'O' ring should work OK (I previously sent one to Doug [dougrail] although he never provided any feedback whether it was used, worked OK, etc.).

Chris Cairns.

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Post by dougrail » Wed Jul 17, 2013 8:46 pm

Hi Chris,

Sorry about that, the drop was muchly appreciated! Your o-ring went into one of my pool of boilers and worked pretty darn well, so I left it be.

Sam - has the one I sent you hen not worked? :(

- Doug

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Post by Lner fan Sam » Wed Jul 17, 2013 8:51 pm

I keep trying using oil and washing up liquid but the o ring keeps sliding out of the recess. When ever I put the glass on it. :roll:
my first live steam engine build thread:
http://gardenrails.myfreeforum.org/about6685.html

Sam Wake

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Post by dougrail » Wed Jul 17, 2013 8:59 pm

Is this using mine?

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Post by Lner fan Sam » Wed Jul 17, 2013 8:59 pm

dougrail:86081 wrote: Sam - has the one I sent you hen not worked? :(

- Doug
It would have had I fitted it correctly to the boiler. :roll:

Its now damaged so I can't use it. :cry:
my first live steam engine build thread:
http://gardenrails.myfreeforum.org/about6685.html

Sam Wake

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Post by dougrail » Wed Jul 17, 2013 9:31 pm

Sam, Sam, Sam....;)

Want to try again? ;)

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Chris Cairns
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Post by Chris Cairns » Wed Jul 17, 2013 9:35 pm

OK Sam, just tried it again so here are some amended illustrated instructions.

1. Put a light coating of oil or washing up liquid onto 'O' ring and push 'O' ring to fit in the boiler cut out. Hold 'O' ring in place with finger (I've not completely covered the 'O' ring with my finger so you can see what I'm doing).

Image

2. Insert plastic sight glass between finger and 'O' ring and slide it down to completely cover the 'O' ring.

Image

Keep finger on bottom of sight glass plastic to keep it and the 'O' ring in place.

Image

3. Whilst holding the plastic and 'O' ring in place slide the brass back plate down over the plastic (my boiler is a riveted back plate version that has been converted to a threaded version so I cannot slide the back plate down any further - the trick is to have your finger in such a place that the slot in the back plate is now over the plastic).

Image

4. With an appropriate tool in the slot holding the plastic & 'O' ring in place continuing sliding the back plate down until the holes line-up with the threaded collars. Fit screws and do them up equally snug - do not over-tighten as that will force the 'O' ring out of the boiler cut out.

Job done.

Chris Cairns.

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Post by Boustrophedon » Mon Aug 05, 2013 11:01 pm

I haven't fitted one to a loco but I have fitted several to Mamod stationary engines. I held them in place with "Hylomar Blue" a Rolls Royce developed sealant than never sets. It has worked so far.

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