Dismantling the Bookham 12/2 CS

[dieselgman]

If that piston was in a typical chromed bore, then the corrosion will likely be isolated in the iron piston and rings. Relatively easy swap to new ones, and another life for the machine! Sweet old machinery, even after it is badly abused!

dieselgman

[vdubnut62]

One can "usually" get a pretty badly stuck iron piston out of an iron cylinder. Try it with an aluminum piston in an iron bore and it will break before it moves.
That's been my experience. Or lack of experience, take your pick.
Ron.

[Samo]

If that piston was in a typical chromed bore, then the corrosion will likely be isolated in the iron piston and rings. Relatively easy swap to new ones, and another life for the machine! Sweet old machinery, even after it is badly abused!

dieselgman

Gary,
Both bores have been sleeved. So I've had them honed by the local engine rebuild shop. There's some stains on the bore, but no pitting that I can see or feel. It might not be perfect but probably good enough for 10-20 years?

Ron,
I think I'm lucky I've got a cast piston.... and I think it will clean up ok. Will share the after pics, after....

Samo

[mikenash]

FWIW I just un-siezed an old 3/1 that had been out in the weather with the ports exposed for at least ten years.

Took the head off, wiped/scraped all the crud out of the barrel above the piston, sprayed a bit of INOX/CRC around the edges of the cylinder and then heated gently with a propane torch until watery, rusty gunge started to bubble up around the edges - no big temperature rise on the cast piston you could still put your hand on it

Wiped that bubbled-up crud away and sprayed some more INOX around the edges and watched it fizz satisfyingly (is that a word?) and left it to cool for a few minutes then heated again.

Did that four or five times then tapped the piston with a bit of wood and a hammer until it started to move

After that it was just a matter of more INOX, patience and a pair of pipe tongs on the crankshaft.

FWIW it has been my experience of many years that heating judiciously, allowing to cool, and application of a penetrant will loosen almost anything. 

Cheers

[Samo]

Mike,

I still have 2 very stubborn change over valves, have the heads upside down, with ATF/Acetone in the void. I've got a 3' long spanner, and tried it a couple of times for naught. I'm expecting it's carbon more so than rust. Reading the forums it taken some huge torque to loosen these, I will try some gentle heat cycling and see how that goes.

John

[veggie]

Yep, mine took a big pipe wrench with a 4 ft pipe extension to get it loose.
The head was still bolted to the engine when I did it so the head was held solid while I reefed on the bar.
Once removed...it did not go back in. I installed a blanking plug.

veggie

[mikenash]

Mike,

I still have 2 very stubborn change over valves, have the heads upside down, with ATF/Acetone in the void. I've got a 3' long spanner, and tried it a couple of times for naught. I'm expecting it's carbon more so than rust. Reading the forums it taken some huge torque to loosen these, I will try some gentle heat cycling and see how that goes.

John

Y'know I had a COV that just WOULD NOT come out.  Tried compression, heat, heat-and-INOX, patience etc etc.  In the end I took the head off, drilled the COV's hole out to 1/2 inch, got a M12 X 120mm long Capscrew and a nut.  Drilled and tapped several M10 threaded holes in a bit of M16 Flat, drilled a central 1/2 hole (cos 1/2 inch is 12.7mm-ish) in that M16. Used my fingers and some cursing to introduce a nut into the combustion chamber and thread it onto the end of the M12 capscrew (already through the bit of M16 flat) so that I had a big solid capscrew through the hole in the COV out the COV port and holding a little bit of M16 flat hard against the side of the head.  Then I used four M10 full-threaded capscrews threaded through the holes in that bit of flat to push against the head and just pull the capscrew & COV out . . . took a bit of doing and a lot of tension before it moved.  I like capscrews cos hey're grade 10 or 12 or something.  Cleaned up the head and stuck a glow plug insert in there.  Just my $0.02.  Good luck with yours

[mikenash]

Mike,

I still have 2 very stubborn change over valves, have the heads upside down, with ATF/Acetone in the void. I've got a 3' long spanner, and tried it a couple of times for naught. I'm expecting it's carbon more so than rust. Reading the forums it taken some huge torque to loosen these, I will try some gentle heat cycling and see how that goes.

John

Hey John - I realise I didn't read your comment properly - you're still trying to get the "outer" bit out.  Sorry - excuse previous rant.- unless you have trouble with the "inner" bit later.  But gentle heat, INOX, and a spanner with a metre of leverage will get that out as long as you have a way to hold the head/motor solidly somehow.  Patience + force will = extraction

[mikenash]

Mike,

I still have 2 very stubborn change over valves, have the heads upside down, with ATF/Acetone in the void. I've got a 3' long spanner, and tried it a couple of times for naught. I'm expecting it's carbon more so than rust. Reading the forums it taken some huge torque to loosen these, I will try some gentle heat cycling and see how that goes.

John

Hey, further to that - in my industry we often have big old irrigation or water supply fittings that have been in place in a well head or similar out in the weather for half a century or so.  You can get one man to hold one end with a pipe wrench and an extra metre of pipe on the handle, and another man to swing on a second pipe wrench with a metre of pipe on its handle too - and they WILL NOT yield.  Eventually you give up because you are going to break something and make the situation worse . . .  But if you heat the "outer" fitting with the butane torch; and take care to heat it all over by moving the torch around its whole surface; and stop what feels like about "half way" to red hot; and occasionally take the torch away from the work and watch for the quick puff of smoke from the joint that tells you the carbon/rust has started to burn - if you do that and then let it cool down naturally, maybe squirting a bit of INOX into the joint and watching it bubble it's way in as the material is cooling from just-a-bit-warm down to cool - then nine times out of ten that fitting unscrews as nice as pie.  IMHO if you warm up the COV valve with the butane - moving it all over and watching for evidence that the carbon is burning out of the join - once it has cooled it will "crack" with leverage and unscrew easily.  Good luck

[Samo]

Thanks I'll let it soak until the weekend, bolt the head back on and try heat cycling it as you describe. Then I'll attack the inside, hopefully it's a bit easier than you describe. The manual suggests to use the engine's compression, but that's out of the question....

Spent last evening in the shed cleaning up the piston, couldn't believe how much carbon was under the rings. Can it build up enough so it seizes the engine?