seized piston

If the piston is not right at the top of its stroke, I would pour in some diesel and leave it for a couple of weeks. Then try to wriggle the barrel up off the piston. 

Best of luck.....Doug

If the piston is at the top of the cylinder then I read of a tip many years ago that may help.  Basically you make a thick metal plate with holes to bolt it tightly down onto the top of the cylinder with an extra hole in the middle for a grease nipple.  Once it is bolted up firmly, use a grease gun to force grease into the gap above the piston and hopefully the hydraulic pressure will force the piston downwards.

I'm not sure how the seized big end will effect this method.  May be worth a try.

Phil.

Just take care it's not overpressurised so much that it doesn't blow up....

It does not blow up unless you use air, grease/oil is uncompressible so as soon as it finds a leak point the pressure/energy dissipates instantly with no dangerous bang. Hence why when you pressurise a central heating system to find leaks you add extra fluid but adding air is not allowed as that still expands explosively.

I found I had a similar problem recently on a Navigator. The piston was not at TDC, but luckily about 1/3 down the bore. Having soaked the top of the piston with diesel & WD40 for a few days, I simply used the cylinder head as a removal tool, by placing a small block of wood on top of the piston and getting the cylinder head to press down on it. If the block of wood does not project too much above the height of the barrel, the existing studs can be used. This proved to be very effective!

I suspect that this method (including the grease version above) will not work if the piston is EXACTLY at TDC, but you would be very unlucky if that was the case.

Having said the above, years ago when i was more green/impatient, I discovered that on a Dominator (unlike a Navigator), one can lift the barrel(s) clear of the crankcase and unbolt the big ends.

I then laid the barrel on its side, stood on it, inserted a block of wood into the cylinder & belted it with a sledge hammer. Cost me 1 fin, but it worked & the barrel was salvaged for further use!

Hi Gary,

Can you say whereabouts in the cylinder it has seized, as in near the top, near the bottom, etc? This could help with suggesting the best way of getting it out.

Regards, 

George 

A friend of mine has use Seafoam additive to free a stuck piston. Pour it into the barrel and let it sit for a few days. My dad did used Marvel Mystery Oil the same way with success.

On youtube, I watched someone try to free a seized piston with a pneumatic hammer. The piston did come free, in several pieces. 

The one time I was faced with a similar problem, paraffin, a block of hardwood and a lump hammer did the trick. And the piston was reusable.