Stuck piston

[Peacons]

Restoring a 64 Allstate Vespa (similar to VNB4/5).

Engine has a stuck piston. What would be the best method to free the piston. 😕🙄

[Dart]

Hi!

The best metod is to spray the WD40 into the cylinder and let it act for at least a day.

Then try to be a piece of wood resting an the piston crow and tap it with a rubber hammer.

Many people use Coca Cola instead of the WD40, you can try both.

[Peacons]

It's been sitting with PB Blaster on the piston top for about a week but no movement that I can see when tapping with a hammer and wood stick.

I may try the cola trick next. Either that or heating the cylinder with a torch and then freeze spray on the piston.

Maybe pull the cylinder studs and twist the barrel to break it free?😳

[Dart]

Well, I would try CocaCola, or to heat the cylinder and cool the piston.

I would keep the last solution as an "extrema ratio".

 

Extrema ratio is a Latin term that means "when you are in despair" 😎😎😉

[Peacons]

Ordered some Kroil, supposed to be best penetrating oil on US market. Creeps into microscopic spaces to dissolve rust. We'll see how that works before the other  methods are tried. I'll keep you all informed on the progress.

[Dart]

1 ora fa, Peacons ha scritto:

Ordered some Kroil, supposed to be best penetrating oil on US market. Creeps into microscopic spaces to dissolve rust. We'll see how that works before the other  methods are tried. I'll keep you all informed on the progress.

Ok, let us know!

[Alevespa]

Hi,

follow Dart's tips.

I were in the same condition, some years ago, with VBB1 piston. In the end I break the connecting rod. But before to to this, try all the alternatives 👍

[Peacons]

Will definitely try everything first. I would really like to salvage this as much as possible.

[Alevespa]

It's the right approach to a good restoration👍

[Peacons]

Thanks all. A photo of the victim.

Also is the number on the sticker in the second photo a paint code?

 

Modificato 7 Giugno 2021 da Peacons

[Alevespa]

Quite similar to the conditions of mine vbb...you need a lot of patience!

the sticker is referred to a final control before leaving from the workshop

[Peacons]

Well engine has been sitting with penetrating oil in it for a few weeks now and the piston still won't budge. Appears to be at BDC so rapping on the piston won t be effective. 
Rotating as far as it will move makes the jug ride up the studs and blocking the bottom of the jug before rapping the piston is still not effective.
Any suggestions to be able to at least salvage the cylinder, crank and con rod, the most expensive parts to replace?

[Dart]

I don't know, honestly it never happened to me. Try asking in a grinding workshop. You can try to open the crankcases and bring the crankshaft, cylinder and piston to them.

[Alevespa]

@Dart it's a good idea. Once removed from crankcase, cylinder can be put into a hydraulic press and piston + shaft can be pushed out.

 

[Peacons]

Excellent suggestion! Will have to remove the stubborn cylinder studs first. Hacksaw as a last resort but will try a stud extractor first as the double nut trick didn't work this time.

[Dart]

Before using the hacksaw know that just remove the two side of the frame, the others you can leave them. Separate the crankcases and take everything to the workshop.