fixing two Century (or at least one)

[Romainpek]

With the help of my son, I managed to remove the flywheel of my engine.



First question: in order to access to the cranckase, I guess I have to remove the ignition base plate, right ?

And in order to do this, I guess I must remove this screw in the center, right ?



It seems very tight, any trick you might help me with ?

[Romainpek]

Finally I removed this screw without damaging it too much.



But then how to remove the ignition base plate ? it doesn't move at all... should I hit it upward with a hammer ?

[Collector Inspector]

You are doing a great job.

Base plate....lubricate heaps and twist side to side.

It will come free.

B

[Romainpek]

Thanks a lot Collector Inspector,

I followed your advice and the base plate came out suddenly



You can see the crankshaft is a bit bent on top, I'll see if I can straighten it.

I then removed the cylinder head, no problem at all, surprisingly.



I removed then the 2 upper nuts holding the cylinder base, but I can't reach easily the 2 lower ones. Do you know which size they are? item 26 below...



In metric, they are between an 11 and a 12, in whitworth, they are bigger than 3/16 and smaller than 1/4. I need to find the right tool...

[never-outbored]

did the flywheel give you some trouble when removing?

[Romainpek]

Hi, not too many problems to remove the flywheel compared to other stuff I must still separate.

Right now I'm stuck with the exhaust pipe for example.

It cannot slide down (due probably to dirt and rust that accumulated) to give me access to the water pipe attachment nut, but also I cannot lift the block away from it because this silly water pipe must be frozen in position in the bottom aluminium piece that receives it.

So in effect, the water pipe keeps everything together, I can't remove it from either end.

[geofflena]

Those nuts should be 1/4 bsf - which equals 3/16 whit ? Maybe someone has bodged some different nuts on.

Even with the correct spanner some can be a tight fit - Its something I have noticed on seagull fixings ?
Tight nuts ( don't search that phrase ! )

[Romainpek]

Hi Geofflena, I think you're right, it's just that my socket wrench was not fully aligned with the nut. I need a set of spanners.

Anyway, I removed the nut with a wrong metric spanner, but gently and after applying heat.


Yesterday I made giant progress, and got most of the parts separated, including the removal of the exhaust tube ! I could force it down enough to have access to the upper nut, which I unscrewed easily



I could play a bit with the exhaust pipe which was heavily bent, and using precision tools, managed to straighten it a bit

BEFORE:


AFTER:



The two most stubborn pieces are these, hopelessly stuck into that "exhaust flange and water pump housing" aluminium thing...



I tried heating it, whacking it, nothing moves.

Is there any easily accessible liquid that could separate this bond between aluminium and steel ?

[Johanna]

Nice work!

I‘m using ceramic paste for nearly every screw that will be need to be untighten one day, especially if it’s getting hot like an exhaust or heater plugs of a Diesel engine. Like this: https://products.liqui-moly.com/ceramic-paste-3.html

And there is also a special stuff called Tefgel, used for any screws in aluminium things in marine use. Like this: https://www.tikal-online.de/produkte/te ... l-tef-gel/

May this is helpful?

[Romainpek]

Thanks for the tip Johanna!

I think it will be great to coat these pieces once freed, before I screw them again.

But now, I need a liquid that will find it way inside, between the seized parts, so I can separate them... coca cola ? gasoil ?

[Johanna]

For a lot seized parts there is a helpful mixture of fire, oil and patience. I’m using a propane gas burner at home and WD40 is my favourite.
For some things we have a oxygen/ acetylene cutting torch at work, what’s a little hotter and helpful for some other things like hard- soldering.
Also helpful is a wheel gun, I own an old manual thing for hammer on and an electric one.

[geofflena]

The leg tube into the gearcase top will not move without heat generally - even with the bolt out its an interferance fit. A lot of heat and tap it off. Getting it back on aligned straight is more a problem - it sometimes helps to tap a wedge between the lugs - and heat it !

Nice tube - brass ? - Would look good polished. They are always difficult to split - just awkward to hold.

Once one has been completely stripped they are a joy to work on. I have just had one apart I had on the rail of my boat as a spare ( 22/ yacht ) - that i rebuilt many years back. I needed to fix some wear on the water jacket - they come apart so easy then.

The proper bsf ' obstruction' spanner ( side jawed ) is a boon to have for a few nuts, I also have a useful array of bsf sockets I picked up on ebay.
I have thrown out so many Whit spanners over the years ! - now I'm re-buying.

I have also made very good use of a simple array of 1/4 and 5 1/16 bsf taps - I bought them singly as 2nd and plug and a small bar holder - very usefull !

[Romainpek]

I got a brand new set of whitworth spanners!!! It will be very useful to re-assemble the thing.



I finally dismounted the damaged half of my crankcase, broken at the stub holding the tiller.



I've sent the two parts to one of my friends, he runs a metal workshop and for him, soldering aluminium is easy. I wait for the return of one single part...

[Romainpek]

I got my part back, I think I can start reassembling this Seagull





I need to order a few bits from John

[Charles uk]

Never weld crankcases without having both halves bolted together, helps prevents distortion.

Reassemble the crank & the 2 crankcase halves, oil the main bearings, check they mate properly, very small gaps can be sealed using RTV silicon as a gasket paste & rotate the crank to ensure it rotates properly with NO tight spots.