HELP big mistake done

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HELP big mistake done

Post  elwood-59 on Sat 05 May 2018, 4:13 pm

Hi all,

Guess I did a big mistake just now affraid

Was trying to fit the cross heads as per instruction, after adjusting the weighshaft bracket firstly. In order to have more room between weighshaft bracket and cylinder I tried to push the HP piston a bit further down the bore. As I had already fitted (but not tighten) the glands it asked for a bit more persuation until it overcame the friction, ending in the piston moving a bit further than expected and wanted.

To make a long story short, it seems like the front piston ring is engaged in the front port. I can move the piston back and forth a bit, but it seems like it is stuck at the piston ring.

Upon assembly of the piston plus rings some time ago I made sure that the ends of the rings were pointing towards the middle of the cylinder block (staggered of course), I made a mark on the piston. Piston still was in the same position, but even by turning the piston now I cannot free it any more.

Yes I khow it was in the instructions to watch out for that...but too late.

Any suggestion?

Elwood, quite desolate Embarassed Sad

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Re: HELP big mistake done

Post  Mark the spark on Sat 05 May 2018, 5:11 pm

I have had similar problems in the past with locos the only thing you can do is try a old type feller gauge down the side of the piston and rotate it to lift the ring out of the grove if that fails then plenty of oil and gentle tap the piston and see if it will move
but you never know someone on here might know a different way

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Re: HELP big mistake done

Post  elwood-59 on Sat 05 May 2018, 6:52 pm

Hi Mark,

Yes, tried that already but either the feeler gauge was too thick or not strong enough, could not get it between cylinder wall and piston ring. Gave up for the moment as Government called to come in.

Hope to find a good solution

Elwood

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Re: HELP big mistake done

Post  lynnr on Sat 05 May 2018, 7:50 pm

Hi

Take the cover studs out where the steam port is. These studs poke through in to the steam space.

Feed a hex key short end of the L in to the hole aiming for piston. It should be able to push the ring back enough to pop the piston out.

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Re: HELP big mistake done

Post  elwood-59 on Sat 05 May 2018, 11:57 pm

Hi Lynn,

Yes that was my next move; I seem to remember having read that somewhere before, maybe in your diary? I’ve given it a halfhearted try l, maybe not with the correct tool though, will search the tool box tomorrow to see which one to try, maybe with some alternations.

Still I would assume there must be a easier way to remove a piston if something fails and piston needs to be out?!? Just wondering.

Thanks and I keep you posted. Will be at STW week after next but would like to avoid to remove the cylinder block just to sort it out Embarassed

Cheers

Elwood

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Re: HELP big mistake done

Post  lynnr on Sun 06 May 2018, 9:41 am

Hi

A 1.5mm or so "L" shaped hex key will be ample. You are only looking for a couple 100ths of a mm movement.

The only safe alternative is drilling the piston out to protect the cylinder bore from any and all damage. I would at this point consider the piston being consumable as fairly "cheap" in comparison to the block in cost and manufacture.

Depending on the gap position and which ring is in the hole a feeler gauge with a thin point on the end might get in to the ring split and allow wiggling but I do not give that much hope.
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Re: HELP big mistake done

Post  elwood-59 on Sun 06 May 2018, 12:27 pm

Hi Lynn,

You saved my day! bounce

Thanks for the help, tried as you suggested with a 2 mm hex key and, after some fiddling as I did not know where the end would be at, I managed to free the piston with some light taps on the piston, just as you explained. Puah!
Piston moving freely again, seems like there was no damage done to neither cylinder block nor piston ring.

Was trying to add some before&after pics, but have not managed imgur yet, and I am at my iPad right now, typing this. Embarassed

Again, thanks a lot Lynn and Mark and for all of you out there: do as I should have and put some cloth or cardboard between piston and front cover until the cover is closed for final step to limit travel of piston. Lesson learned!

Elwood  Very Happy  Very Happy

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Re: HELP big mistake done

Post  lynnr on Sun 06 May 2018, 12:35 pm

TA DA


sehr gut

auf Wiederhören

Lynn
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Re: HELP big mistake done

Post  elwood-59 on Mon 07 May 2018, 11:19 am

As promised:

Before


piston ring in port Embarassed

with tip / trick of Lynn



solved

As you can see the two „middle“ threads to end in the port. Just had to figure out where to press, top or botton end of port.

tool used:



hex head key 2mm with mole grip for leverage

and in order to remove the studs I used this tool:



long nut with grub screw to lock the stud in the nut. I find this easier than the dome nut supplied and you can also use it to uncrew the stud in case of need. Just use a bit more torque on the grub screw. Yes, double nuts also work, but I found this gadget easier to work with.

Cheers


Elwood

PS yes I cleaned up the threads before reinstalling the studs Very Happy

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Re: HELP big mistake done

Post  Capricorn1 on Wed 16 May 2018, 11:12 pm

In case this happens again try some 0.010" thick shim steel, a length long enough to go almost the circumference of the piston, feed it in opposite the steam port and with some patience and jiggling you should be able to lift the offending piston ring out of the steam port.

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Re: HELP big mistake done

Post  elwood-59 on Thu 17 May 2018, 12:49 am

Hi Capricorn1,

That actually was my first idea: to get a feeler gauge between cylinder bore and piston ring, tried 0,2 mm so less than what you suggested but gave up after about 10 min, just could not get the strip in. And thinner shims like 0,1 mm (~0,004”) just was not strong enough, it just buckled.

So in the end Lynn’s idea proofed to be the best way to go for me, took me longer to prepare than to actually push back the ring.

Might try again next time, but will postpone that to first major overhaul, hopefully still a long time in the future.Very Happy  

Cheers

Elwood

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