seized piston help please

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BOATKID

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My Panda Genset has a seized piston/rings due to sea water lying in it for 18 months and I cant get it to budge, the liner looks salvageable with a hone, so what are my options the get the piston to budge ????

Engine is single cylinder farymann 7.7HP

should have said that the piston is still connected to crankshaft but the cylinder pot is free from crankcase
 
hot oil

a couple of years ago i was talking to someone who had a seized 2 stoke outboard he was told to heat some thin oil up on a primus really hot, tho carefull not to set it allight and then put that in . he tried it and got the engin turning ... Its still running !:)
 
The old remedy is a 50/50 mixture of parafin and engine oil, mix up a bucket full and leave the engine in it for a week. it should free every thing off.

good luck
 
thanks for tips guys - I left penetrating oil in for a few days however I did notice it did not drain down - maybe worth trying again for a bit longer !!!
 
BOATKID said:
My Panda Genset has a seized piston/rings due to sea water lying in it for 18 months and I cant get it to budge, the liner looks salvageable with a hone, so what are my options the get the piston to budge ????

Engine is single cylinder farymann 7.7HP

should have said that the piston is still connected to crankshaft but the cylinder pot is free from crankcase
Click to expand...
Its a combination of moving, bashing, wd, penetrating oil, bash, fiddle bash, heat and eventually it moves a bit then its a case of working it until it comes out, resist too much movement when it starts to move because you can break things. When you get the piston out do the same sort of thing and you might get away with a set of rings plus a hone. If you are near Llangollen or Pwllheli, I have a hone that peeps can hire for a modest beer tokens contribution!
Stu
 
Humblebee said:
Cola is a weak acid and might work, it's good for cleaning bright metalwork and coins, but i think vinegar would be more effective on an engine.
Click to expand...

The "working" bit of Coke is phosphoric acid which actually is a stronger acid than vinegar... (pKa of H3PO4 ~ 2.1 v's CH3COOH ~ 4.7).

I wouldn't put acid in the "pots" as you are trying to "dissolve" rust down a very fine cavity between the piston and the cylinder, which is going to take a very long time. In the meantime the cylinder and piston will be getting damaged/pitted.
 
Similar thing happened to an old Matchless 350cc single I had in the late 50's and I got a result. Never stripped it and it went on for years after..

A LOT of heat around the outer cylinder/barrel. We had blow lamps. Four I think.
With boiling hot diesel poured in on top.
A round wood bock placed down through the diesel to touch piston top.....with some firm bangs.
More heat, + all of the aforementioned.
Don't try too hard too soon.
Wear safety googles, gloves etc, with hot oil etc...
 
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Thistle said:
Do remember that hot oil has a "flash point" ... it's called that for a pretty good reason.
Click to expand...

true but is this only likely to flame rather than have any other serious consequences?

Mind you, when we were kids, it was fun to make explosions with sawn up pieces of lead pipe hammered over, fertilizer, sugar and a penny banger fuse. It's a wonder I got to the age of 12.
 
Scotty_Twister said:
Mind you, when we were kids, it was fun to make explosions with sawn up pieces of lead pipe hammered over, fertilizer, sugar and a penny banger fuse.
Click to expand...

Scary to think that these days you could be blowing bubbles for the CIA in a bath of water in Egypt if you got caught doing this - especially if you've got a permanent tan :(


For the siezed cylinder, I wouldn't put anything water-based into it (vinegar, coke, etc.). Fill the bore with diesel and let it soak for a week. Meanwhile whittle a piece of strong timber to be a good fit in the cylinder - it must bear on as much of the piston as possible. Return to engine, insert timber and give it a reasonable thump.

If the piston moves a little, STOP! try and bring it back in the opposite direction by turning the crank / tapping on the big end, if you've got access. You should find that the piston will move a little bit in each direction quite freely, but will then come up against corrosion, etc. More diesel in the top, and keep turning it between its two limits. The travel will gradually increase until it will go the full stroke.

If piston doesn't move, then try warming the block up by whatever means you have at your disposal and try again. You can hit the top of the piston quite hard if your piece of timber covers the whole of it. (It's very easy to knock a hole in the piston crown otherwise.) As soon as you get it to move, try and work it backwards and forwards, as above.

18 months is a long time for it to have been full of water, though.

0.02p

Andy
 
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Thistle said:
Do remember that hot oil has a "flash point" ... it's called that for a pretty good reason.
Click to expand...
We used to "boil" bearings in oil to make them expand, used an oxy acetylene torch one time, fecked up and got it too hot, the bearings turned blue. The oil didnt ignite even at that temp. Dont forget engine oil is designed to be sprayed on the under side of v hot pistons at full chat, it is designed to continually lube cylinder walls at full chat in the middle of controlled explosions. Under the circumstances being discussed I dont think that he needs to worry about it combusting.
Stu
 
Scotty_Twister said:
true but is this only likely to flame rather than have any other serious consequences?

Mind you, when we were kids, it was fun to make explosions with sawn up pieces of lead pipe hammered over, fertilizer, sugar and a penny banger fuse. It's a wonder I got to the age of 12.
Click to expand...
We used to use copper pipe, then we found out that if you trap a bit of the powder in the fold it would spontaneously combust!
We then moved on to welding nuts together and screwing short pieces of thread in to each end. Think of one and a half inch BSW studs and nuts, made rather satisfying bangs! My mates uncle had a disused garage which we used to test one, feckin hell, it nearly demolished it!
At one point, when we discovered the ingredients of gun powder, the local chemist was quite happy to sell us potassium nitrate and sulphur! Wouldnt happen today!
Stu
 
Agree from the seized engine I have worked on over the years. lots of thin penetrating oil for a couple of days followed by a judicious belting with a timber thid is probably the best course of treatment.
I had not thought of Coke, but the combination of phosphoric and citric acids is a potent mixture as the citric reacts with iron to produce ferrous citrate, and this is why it is used for boiler cleaning.
If you can make the timber thid slightly concave so that the pressure is transmitted to the edge of the cylinder head, you have less chance of damaging the crown.
When you get the piston out you will find it was the rings which have corroded into the bore, and almost invariably they will come out in bits, having broken in the extraction process. If you have access to a large propare gas torch heating up and cooling down the engine can break the seal so that the oil can start to work. Good luck!
 
BOATKID said:
My Panda Genset has a seized piston/rings due to sea water lying in it for 18 months and I cant get it to budge, the liner looks salvageable with a hone, so what are my options the get the piston to budge ????

Engine is single cylinder farymann 7.7HP

should have said that the piston is still connected to crankshaft but the cylinder pot is free from crankcase
Click to expand...

C'mon BOATKID how'sya doin.......can't you see we're all trying hard for you.......result???
 
skipper_stu said:
We used to use copper pipe, then we found out that if you trap a bit of the powder in the fold it would spontaneously combust!
We then moved on to welding nuts together and screwing short pieces of thread in to each end. Think of one and a half inch BSW studs and nuts, made rather satisfying bangs! My mates uncle had a disused garage which we used to test one, feckin hell, it nearly demolished it!
At one point, when we discovered the ingredients of gun powder, the local chemist was quite happy to sell us potassium nitrate and sulphur! Wouldnt happen today!
Stu
Click to expand...

thanks skipper_stu, just got in from a few days on the boat.....shattered..... and needed a laugh.
It's amazing what we used to do before t.v. was in every home
At about the age of 11-12, we used to have a big rope swing in the woods... from the bow of an enormous tree. The swing crossed a pond.
We used to play chicken on who could swing the most times before jumping off the other side.
Too few swings and you went in the deep end of some very smelly deep mud. :-)

beat that!
 
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