Forum

[Chris Tindal]

My old seized bullet engine that has been stood for decades still wont budge. Its been soaked in diesel for about 6 weeks now but is still stuck solid. Any more tips on how to free it up? Will I have to drill through the piston crown and gradually break it up?

Cheers

[Mark M]

Chris, I think you should persevere with the Diesel method but with a bit of variety, that is, drain off diesel, heat piston with hot air gun or similar and then a few stout wallops with big hammer and a wooden drift on the crown and if it doesn't move then, re-fill with diesel and soak. I've heard that Coca Cola can work to free rusted rings but don't have any experience of this! Heat force and penetrating oil do tend to work in the end! Good luck,
REgards, Mark

[Les H]

I don't think heating the piston will help much as it will expand in the bore and just ram the rusted rings even harder against the bore. Heating the barrel would help in theory but in practice would be nearly impossible to get enough heat into it. I would get a length of 3"x2" timber and about 6" long and thump it down hard against the piston with a club hammer. Your soaking will have helped and now it just needs a clout to shift the piston. Hopefully the piston is not at TDC or BDC?

[Les H]

The fact that Coca Cola might have some effect is that most fizzy dinks contains Phosphoric Acid. Most metal cleaner/rust removers are based on phosphoric Acid, so if you have some try that sloshed around the piston, it will not need soaking more than half an hour, and don't let it dry out as it forms a black residue, if left too long.

[trevorch]

Hi Les H, You were writing while I was still thinking and trying to watch the Open. Heat, I agree with your sentiments entirely.

Rather than the " if at first you don't succeed, get a bigger hammer" approach", I would suggest air pressure. Modify an old spark plug and attach to an air compressor, assuming head is on and valves not leaking too much. This will certainly help to push the diesel oil down quicker and 150 PSI on this size of piston is over 1,000 lbs force. Worth a try? Cheers TrevorCH

[simon]

I think coke works on the same basis as molasses in removing rust. I don't know if any of you have tried this but molasses diluted at around 20:1 in hot water will in about a week to ten days totally remove rust from any ferrous metal leaving it completely clean and grey. It's slow but totally non destructive. With a seized piston though I agree with the 3x2 method a gentle thump with a big lump hammer on a bit of 3x2 framing timber should get things moving.

[Chris Tindal]

Thanks everyone, I'll give all the suggestions a go a let you know when, if and how if frees up.

[Mark M]

Les, the idea behind heat and a wallop is to break the rust seal allowing the penetrating agent to do it's work once the piston has cooled. It's the same principle as used on other stuck items, for instance I recently got the seized swinging arm spindle out of a Connie by repeatedly using this cycle of heat, cooling and oil. Black syrup (molasses) is a fantastic rust remover as described, I've used it to de-rust the inside of tanks before, really effective!
REgards, Mark

[Chris Tindal]

Its free! a good wallop on a piece of wood and the piston slowly went down, sprayed some WD40 in and it soon started moving easier until I could turn the crank by hand. The diesel must have been working all along, I was just reluctant to hit it. Any tips on how to seperate the crankcases? I'm a bit hamfisted and dont want to damage anything.

[Mark M]

Well done Chris, what did I say?! To split cases, just undo every through bolt you can see and gently tap round the main joint with a soft hammer until it starts to part, then you can tap on either mainshaft to help assist passage through bearings. These may be tight if it's that rusty. Do remember to take the timing gear off the end of the right hand mainshaft first! The oilpump worm is Left Hand thread and tricky to get at, I use a cheap 19mm spanner that I've ground thinner. The gear on the crank can be hard to remove as there's little room for a puller, this is one of the few special tools that are a good investment on a Bullet.
REgards, Mark