Boiler rust removal & general Mamod resurrection.

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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Boiler rust removal & general Mamod resurrection.

Post by big-ted » Wed Nov 19, 2014 6:42 pm

So, I'm coming back to the UK for a Christmas visit, and high on my list of things to do is resurrect the Mamods out of my Dad's garage and give them a run. My dad and I each had a starter set. Mine is a maroon RS3 with the brass chimney, and his was a green RS1. Mine was fitted with a gas burner of an origin I've long since forgotten.

Aside from a thorough clean up and oil-round there are a couple of issues I remember from the last time I tried to run them ~ 12 years ago.

My set was bought from Reading Toys R Us for my 10th birthday/Christmas present for the sum of 124 pounds. The loco always ran fantastically, but at some point I let the boiler run dry (ah, the ignorance of youth!) and some of the black paint burnt off. I caught it pretty quick, so no further damage was done, but I suspect surface rust will have set in to the boiler. Is there any harm in rubbing it down and repainting with black high temperature paint? The idea of leaving behind a thinner wall thickness after rubbing down on a pressure vessel makes me nervous. Further, as it is rivetted together I'll have to drill out the rivets to remove the boiler and bolt back together. How easy is this to do with a hand drill as opposed to a pillar drill?

Dad's loco was bought second hand from a train show somewhere, and when we got it home we realised the previous owner had melted the sight glass. Dad sent it off to be replaced by one of the Mamod fettlers that were around at the time (again, ~20 years ago!) but when it came back it still leaked from the bottom of the glass, and we never fully sorted this. I'm guessing it needs the o-ring replacing? I'm going to have Dad check that the back plate is now bolted on following the glass replacement, and if so I'll have a go at replacing the o-ring myself. Does anyone know the recommended o-ring code? I realise o-rings are available from Dream Steam (who appear to have acquired a dubious reputation of late?) and Roy Wood models, but I feel bad asking them for a single part as the sale total wouldn't justify their time to stick it in an envelope...

I have a nasty suspicion at least one set was stored with the solid fuel tablets in the box. Fortunately the boxes were thoroughly disintegrated, so I'm hoping any outgassing was allowed to vent and hasn't corroded anything too badly. Again, I didn't know any better when they were put into storage all that time ago.

I'm thoroughly excited about being reunited with my trains and having a Christmas project to work on. Plus, I'm kind of hoping I can inspire my Dad to start to build a garden railway whilst I'm home... :)

Pics to follow when I return to UK shores Decemebr 22nd!

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Re: Boiler rust removal & general Mamod resurrection.

Post by Superbiker_uk » Fri Nov 21, 2014 7:15 am

Hi big-ted - sounds like some fun is planned for those Mamod Steam Railway sets over the festive period :)

Just thought I would pick up on your questions:
big-ted:105790 wrote:....but I suspect surface rust will have set in to the boiler. Is there any harm in rubbing it down and repainting with black high temperature paint? The idea of leaving behind a thinner wall thickness after rubbing down on a pressure vessel makes me nervous.
The boilers are made from drawn brass and will not rust. It is quite usual practice if re-conditioning / restoring the boilers to remove the old paint and then re-paint with VHT paint. You can use wire wool or a brass wire wheel to remove the old paint with very little effect on the metal.
big-ted:105790 wrote:Further, as it is rivetted together I'll have to drill out the rivets to remove the boiler and bolt back together. How easy is this to do with a hand drill as opposed to a pillar drill?
The rivets are easy to remove but care is needed to only remove the rivet head rather than drilling right though - that way there is less risk of enlarging the rivet holes and making it harder to seal with the new rivets. Once the rivet head is removed the boiler back plate will come off. You will then need to carefully remove the remaining part of the rivets. New rivets must be closed end copper rivets not the standard auminium type ones. I drill out using a hand drill. I think you would find it pretty difficult to set up the loco under a pillar drill - in any case, you don't need to as a hand drill will do the job perfectly well.
big-ted:105790 wrote:I realise o-rings are available from Dream Steam (who appear to have acquired a dubious reputation of late?) and Roy Wood models, but I feel bad asking them for a single part as the sale total wouldn't justify their time to stick it in an envelope...
Personally I would order the correct part from Dream Steam and purhcase a new o-ring and new sightglass kit. Roy Wood may have them available but he does not use standard Mamod/MSS boilers in his very fine models so may not be able to supply. I have used Dream Steam many, many times and the service is very good - whilst you are ordering the new o-ring and sight glass kit, order the correct copper rivets for the job aswell.
big-ted:105790 wrote:I have a nasty suspicion at least one set was stored with the solid fuel tablets in the box. Fortunately the boxes were thoroughly disintegrated, so I'm hoping any outgassing was allowed to vent and hasn't corroded anything too badly. Again, I didn't know any better when they were put into storage all that time ago.
Hexamine tablets love moisture and this is the reason they are not good stored in the loco boxes - unless the loco box is in an area with dry air. The damage from the storage will normally affect the mazak cast parts like hand rails and possibly wheels. The body work can also craze under the paint with the effect that the paint can detatch. Just give the loco a good looking over and service it prior to steaming and you should be fine.
big-ted:105790 wrote:I'm thoroughly excited about being reunited with my trains and having a Christmas project to work on. Plus, I'm kind of hoping I can inspire my Dad to start to build a garden railway whilst I'm home...
Have fun!!

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Post by Chris Cairns » Fri Nov 21, 2014 7:41 pm

Peter has comprehensively covered your questions but I would just like to reiterate the damage caused by storing it with damp solid fuel tablets. It will discolour all the brass fittings (which can then be difficult to clean off) and causes a sort of corrosion to the mazak fittings. This can include eating away the handrails, and some serious bubbling into the smoke box casting & rear drag beam. I was discussing this particular problem with a visitor to our layout at a recent Show who had his father's old RS set stored away in the loft and recommended he removed any solid fuel tablets straight away.

I have discovered over the years that the seal used for the sight glass plastic has changed (originally it was an oval seal, then became an 'O' ring) and with inconsistencies in the depth that the boiler back is punched out to you can find that the current supplied MSS 'O' ring (sold by Dream Steam & RWM Steam amongst others) does not have sufficient cross section to be compressed properly to make a seal and if you are using blind copper rivets these would need to be drilled out again to start over again. I have found that an 'O' ring of 18mm inside diameter & 2mm cross section works OK, although I prefer to use the oval seal that Mamod use with their current sight glass models (it may need trimming down to fit your particular boiler fitting). If you talk to Mamod nicely they may send you one or two in the post for free.

I would recommend soft soldering 2 x 6BA bolts/screws into the boiler backplate and use 6BA nuts & washers to retain the sight glass fitting, it makes it easier to replace the plastic sight glass the next time. See here - http://www.hglw.co.uk/Replacing%20a%20M ... lastic.pdf and here - http://gardenrails.myfreeforum.org/about7433.html

Be aware that old solid fuel tablets retain moisture that can cause the tablets to explode firing bits out everywhere when firing your locomotive. So no running it around on a carpeted floor indoors!

Chris Cairns

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Post by big-ted » Fri Nov 21, 2014 9:13 pm

Thanks a lot for the input both of you. Interesting the boilers wont rust. I definitely remember mine having what looked like rust on it, but maybe my memory is playing tricks on me.

Yep, I have soft soldering equipment available to me, so maybe soldering bolts to the inside of the boiler is the way to go. I'll try and pick up some suitable bolts here in Canada before I leave as I wont have time before places close for the holidays when I arrive in the UK.

And I'm just crossing my fingers re: damage done due to the solid fuel storage situation. My Dad's garage is certainly not the driest environment...

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Post by steampig » Sat Nov 22, 2014 12:16 pm

Good luck. I find the pleasure of fixing up something broken much greater than acquisition or construction - possibly because the gratification is cheaper and faster!

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Post by big-ted » Sun Nov 23, 2014 2:19 am

WARNING! The following photos are not for the faint of heart!

So my Dad went out to the garage to inspect the locos and take pictures for me. This is what he found. Bear in mind these have been in storage for ~15 years or so...

Image

Image

Image

He's given them a bit of a clean as he felt bad sending the above pics to me!

Image

Image

Clearly, I'm going to have to get the black paint out on the handrails etc. I can't really tell from the pics how bad the wheels are...

On the bright side, the water gauge on the green loco is already screwed on, so that should make resetting the seal a little easier...

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Post by Chris Cairns » Sun Nov 23, 2014 4:22 am

OMG!

A picture or two which clearly shows why you should not store those mazak castings near damp solid fuel.

Looks like it is all just on the surface so hopefully those wheels are salvageable.

Worth carefully looking over the track as well as it is also made from mazak.

Those are going to keep you very busy, with all the cleaning and painting required.

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Post by Superbiker_uk » Sun Nov 23, 2014 8:31 am

WOW :shock: :shock: :shock: That's as bad a case I have seen of errosion of the mazak wheel castings on a Mamod. I do hope those wheels are going to be OK. Good luck and most of all have fun!

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Post by big-ted » Tue Dec 23, 2014 3:59 pm

Work has begun!

However, first problem & potentially most troublesome thing I notice is that, on the red loco, 3 of the 4 wheels spin freely on the axles. Is there an approved method for re-quartering & re-fixing the wheels?

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Post by Chris Cairns » Wed Dec 24, 2014 1:36 pm

big-ted wrote:Is there an approved method for re-quartering & re-fixing the wheels?
Various techniques have been adopted over the years, but here's mine that uses the original components.

After moving the bearings to the opposite end hold the axle using a pair of mole grips (yes they will burr the axle which will need carefully filing down) and gently prise off the offending wheel vertically. Degrease the axle end and wheel hole, then roughen up the axle end with coarse sandpaper. Using Loctite 603 (with activator first if available) fit the wheel back onto the axle end making sure it is square to the axle, and you can set the 90° quartering manually by seeing the inside end of the coupling pin on the opposite wheel through the appropriate hole in the wheel being fixed back on. Let the Loctite set (I leave mine for a day) then wipe off any remaining Loctite left on the axle (otherwise it will set the bearing in place later!). If both wheels need repairing you will need to file the mole grip burrs off the axle to allow the bearings to be moved to the opposite end, then repeat as above for the 2nd wheel. When doing both axles on a locomotive make sure the 90° quartering is the same on both axles.

There are other methods like re-punching the axle ends (never worked for me long term), or fitting a pin between the wheel and axle to stop it rotating. A Mamodification offered in the past was to replace the shouldered axles used by Mamod/MSS with plain axles but that needs the wheel hole opening out carefully (many of these wheels were drilled out of true).

Best of luck!

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Post by big-ted » Thu Dec 25, 2014 6:44 pm

Thanks chris. Turns out the crank pins are also loose in the leading wheels, so I think a new set of wheels is on the cards. That said, the loco ran remarkably well all things considered. It pulled 3 mamod wagons around for 10 or so laps of the large oval my dad & I built in his conservatory. It clearly wasn't happy from the clicking of the motion from the timing being so far out, but after 15 years in storage I was remarkably impressed!

The green loco even managed to pull all 5 of our Mamod wagons for a couple of laps after I replaced the sight glass & oiled around.

What was less successful was the dream steam meths burner I bought specially for the occasion. Try as I might I cannot get it to stay lit. Time to search the forum & figure this out as I know someone has covered this somewhere...

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Post by Chris Cairns » Fri Dec 26, 2014 4:18 pm

Yup, loose crank pins is another failing which then leads to permanent wear of the cylinder end cap by the piston rod due to all the sloppiness. I repunch the coupling pins when I remove a wheel from the axle.

With regards to your 3 wick burner you probably need to repack the wick material. If it is packed in too tight it will prevent the meths flowing due to capillary action. It is also quite common for the front wick to go out quite early into a run which I understand is due to the design of the burner tube, so putting a slight bend downwards between the front & second wick tube may help there. Dream Steam also use a vented filler bung - worth checking the vent is clear (most of my burners came without vent bungs/caps but I've yet to suffer a flare up in the cab because they are missing).

Chris Cairns

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Post by big-ted » Tue Dec 30, 2014 5:59 pm

Well, I fly back to Canada in the morning. Dad & I almost managed to get video of both locos running at once, but chasing two mamods, operating points, AND taking video proved too much for two people. Still, I think I have the meths burner working to my satisfaction, only now the reverser valve seems to be leading stream faster than the boiler can make it on the green loco (soon to be named Rhiannon & numbered no. 3 according to dad). No. 4 ran well up until this evening when I think the slop in the motion finally got the better of it. However, dad & I had a lot of fun resurrecting them, & that's the main thing.

I'll be back again with some new wheels, a drill to get the reverser out of no. 3, & some more meths (& possibly some more wagons!).

Pics to follow when I get back to Canada!

Thanks for all the advice, & happy new year to all!

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Post by Superbiker_uk » Tue Dec 30, 2014 6:14 pm

Well done with the loco's and it sure does sound like fun - and like you said the fun you had with your father is the best part :)

Safe travels and I look forward to some pictures/video when you get back to BC.

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Post by Chris Cairns » Thu Jan 01, 2015 3:21 pm

I echo Peter's (Superbiker_uk) sentiments that it is great to read that a good time was had by all as running Mamod's can be frustrating at times.

The reverser valve leak can have several causes, with one being the steam takes the least path of resistance to escape thus if the quartering is badly out that could be a cause - there are several more like duff 'O' ring seal, etc.

Look forward to the photos and the next Chapter in due course.

Chris Cairns

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