Success rate in freeing seized motors

[jerseydave69]

After wrecking another motor while trying to free the seized piston ! The question is ...What success rate do you get from trying to un-seize a motor?
I have tried various ways ..All the tips passed on from you guys ! And in reality ,the chance of freeing a seizure is pretty slim with out damage to either the conrod or piston .....or both ! I tried a Century, Silver Century, and two Forty series motors , All seized at TDC .
On a separate Seagull ,because the outer block was cracked , I used an angle grinder to cut part of the way through and split the block away from the piston to save it! That was a success.

Question.. How many Seagull outboard motors, have you had any success in freeing ?

[Nudge]

I have done 3, All a success. I made up a bung that fits in the plug hole with a grease nipple on it. First off, clean up behind the piston (if you can get to it) no point in trying to push against all that crud!
I start off by filling the bore with oil / diesel, put the bung in then heat the head / block with a gas torch. it has to be quite hot - you need the oil to expand and force its way down past the rings. leave it to sit for a day~ week or so for the oil mix to do its work.... dont rush it. Next is the grease gun, just pump enough grease in there to get things to move or you will end up using the entire tube!! once the piston has started to move take the bung out and push the piston all the way back in. Repeat the process as many times as required .
The thing with using oil and grease to push the piston; is it keeps an even pressure over the face and you won't punch a hole in it or otherwise crack it.

[jerseydave69]

With all the motors i tried freeing..All were TDC so couldn't get to the back of the piston. I soaked the piston crown with plus gas with the head off after trying the deisel/oil and even the plus gas wouldnt drop down the side of the piston.

The grease nipple on a bung sounds interesting though.. What sort of preasure is needed to force the piston down? My grease gun would break with such a force pushing the handle that hard. Not much grease would be needed as it's at TDC.

Dave

[Keith.P]

I do pretty much the same thing, plus gas, WD, what ever you use, put plenty in the plug hole, then put the spark plug back on and add a little heat, don't go made just enough to get things bubbling and then let it cool, this can be repeated, if needed.
I use a threaded bar the same thread as the plug hole in the spark plug hole to start moving the piston, it works better on some than others, because of the angle of the plug hole, I have not lost a con rod or piston yet.
If you rush, it will break.

[Hugz]

When you say threaded bar do you mean 18mm wound down to keep pressure on the piston? Sounds logical.

[Keith.P]

When you say threaded bar do you mean 18mm wound down to keep pressure on the piston? Sounds logical.

The piston crown is pretty heavy duty, so I just do the heating process until I get some movement, but either way will work, you just don't over tighten it, its only the rings that need to be freed up most of the time, that,s an 18mm 1.25 thread.

[jerseydave69]

That sounds like a really good idea Keith, I will definitely adopt that idea on the inevitable next seized motor.

[Hugz]

Maybe a small thrust washer added to the end of the threaded rod to stop grinding into the piston. Can be tapped and screwed into the end. How strong is the head thread? I've never stripped one but I hear it is common but then again making a plug with a nipple and putting it under hydraulic pressure would also put a strain on the thread. Maybe they strip because of peeps crossthreading?

On the square blocks wouldn't you just take the head off?

[Oyster 49]

Patience is the main thing!

[Charles uk]

Gently does it!

& perhaps the end from a small G cramp.

[Hugz]

I think we should give Keith the most innovative Seagull tool of the year award.

Who has a lathe that can make these and spread far and wide?

[Keith.P]

I have an old three legged puller, you all know what that is used for and before you say it, its not for pulling your leg.
The centre threaded bar is an HT 18mm 1.25, made with a nice nut on the end, that's what I use.
If you are worried about damaging the 18mm plug thread, why not use an old two piece spark plug, just the bottom, drill and tap a thread in the plug centre and use a threaded bar of the reverent size, it wouldn't take much to make one.

[Hugz]

They have become a bit too collectible to modify

Its had a hard life

[Hugz]

How cool is this, shame it is not 18mm. A whistle on our seagulls. Wonder if you can get a 1/2inch to 18mm adaptor? 3mm sides might be a bit thin after thread cut into it.

http://www.ebay.com/itm/Spark-Plug-Whis ... SwX~dWnA0i

Toot toot. I think it might warble a bit with suck and blow action

[Keith.P]

Ok, use this. http://www.ebay.co.uk/itm/Spark-Plug-Th ... xygLxSZoeS

Yes, we all have the odd old spark plug.