Rusted Piston Removal

[Art]

'72 M10 block.  Everything is off and out except for two pistons.  I have soaked them with PB Blaster for days and penetrating oil 24 hours.  Using wood and rubber mallet from underneath trying to not damage piano pistons.  I plan to use the block for rebuild and possibly the pistons but I am concerned the medium force of beating them out will damage them. Contemplating heating the block with propane torch. There is a good amount of surface rust above the remaining pistons.  Looking for advice.  

[PhilC]

Deffo get some heat on those. MAPP would be better than propane. The heating/cooling cycle will free them up eventually with some battering with a mallet and wooden block. I watched it done on TV and it was surprising how hard the guy was hitting them.

[tech71]

1 hour ago, Art said:

Using wood and rubber mallet from underneath trying to not damage piano pistons.

Those are most likely done for, the ones I have encountered in your situation have been pitted/corroded.

Clean the bores, sandpaper, hone, something. Try driving them downward just a little to break them loose. Use more penetrant . 

I wouldn't worry about damaging those pistons, they have had it anyway.

 

1 hour ago, Art said:

There is a good amount of surface rust above the remaining pistons.

remove it

Edited March 5, 2023 by tech71

[2002Scoob]

Yah, I dunno why you're even thinking about the pistons having any sort of after-life. Those things are more than likely cooked. 

 

And judging by how rusty the cylinder walls are you're gunna need to bore them out a bit to clean it up so you'll be sourcing up-sized pistons and wouldn't be re-using the slugs anyway. 

 

Clean up the walls as best you can to prepare them for coming out the top.

 

If the cylinders will hold liquid I was always curious how well it would work to put the block in a plastic bin, fill the cylinders with some rags or sponges and top em up with Evaporust- With the idea that the rags/sponges would help retain the product- and keep things bathed in it's juices. 

 

Never tried it. You're welcome to guinea-pig it for me

 

Or just bust out the heat and abrasives!

-J

 

Edited March 5, 2023 by 2002Scoob

[tech71]

Make something like this from an old hacksaw blade and dig out as much of the crud around piston as possible.

Apply penetrant, repeat.

This one is a chip chaser, you could omit the hook, just square off the end.

How big is your hammer? 

Edited March 5, 2023 by tech71

[roadhog0]

No way I would rerun those pistons if it was me. Especially since that engine will need a rebore with rust like that. Wire brush the area around the top of the piston then cover piston area in an ATF/Acetone mix and let sit overnight. You can also heat as it will definitely help. Then you're going to have to get the wood and a big hammer out. 
Good luck!

[Mike Self]

Agree with other posters...the required whanging at those pistons will most likely damage the ring lands, as most of the "stuckness" is the rings rusting themselves to the bore, vs the pistons themselves.  But it's worth a try to extract them (kinda) gently, if for no other reason to see what they look like--for future reference yourself, and your audience (we can learn stuff too!).

 

The larger the wood block you can stuff down the cylinder, the better chance you have of freeing those rings without collateral damage.  A small round(ish) tree trunk or limb section that will just fit down the bore will put more of the pressure on the outside edge of the piston; or, the largest piece of plastic plumbing pipe that'll fit down the bore--topped with a piece of wood--will concentrate the force around the piston's edge, where it's stuck...

 

This is the time you may wish you had a wet liner engine with removable cylinder barrels, like the old Triumph TR 2/3/4, older Peugeots and Renaults.  Just unbolt the connecting rods and pop the stuck pistons and cylinders out of the block, replacing with new.  Job done.

 

mike

 

PS 

[TobyB]

At the risk of sounding defeatist,

 

the only reason to remove those pistons is if you want to save the rods.

 

The block may be sleevable- but there are lots of M10 blocks out there, still.

I suspect.

 

I agree with all of the above, as to getting them out- but in your place, I'd mount

that boat anchor onto the mill, and open each bore with a boring head and

a carbide tool to skuzz out the rust.  But I suspect you'll be well past 89mm by 

the time you hit solid iron...

 

t

glass mostly empty

[jgerock]

BTDT.  Ball peen hammer and piece of thick walled pipe eventually freed the pistons from their rusty bores. This was after I soaked the bores with PBlaster, ATF/Acetone. Engine was toast and hauled to the metal recycler.

[Art]

7 hours ago, Art said:

'72 M10 block.  Everything is off and out except for two pistons.  I have soaked them with PB Blaster for days and penetrating oil 24 hours.  Using wood and rubber mallet from underneath trying to not damage piano pistons.  I plan to use the block for rebuild and possibly the pistons but I am concerned the medium force of beating them out will damage them. Contemplating heating the block with propane torch. There is a good amount of surface rust above the remaining pistons.  Looking for advice.  

Great advice everyone.  I included photos of the other two cylinders.  Not ready to give up on  the block yet but I understand the odds are against me. Pistons are toast but will be liberated soon after some applied heat.  I will post some photos later of the crank and the head as they are in better shape.  

[Conserv]

Looking at these latest photos, those are mighty-low piano tops. They may be 8.3:1, but are possibly 8.1:1, pistons. 8.1:1 piano-top pistons for a standard bore — we don’t yet know if these are standard bore — have little market value even if they are in very good and cautiously re-usable condition. Maybe $100-$150, for the set of four (if not free). Again, that’s in very good condition.

 

As to the block, your best hope, short of sleeving, is probably that the worst of your bores will clean up at second oversize (approx. 89.5 mm.) or third/fourth oversize (approx. 90.0 mm.).

 

Sleeving is proven technology, and not particularly expensive since you’re re-boring anyway. But… as @TobyB and others have said, why sleeve when good blocks are plentiful? For ‘02’s, where nearly a million were manufactured, I’d reserve sleeving for saving an original numbers-matching block.

 

The secret to old car happiness — and happiness in general — is low expectations. Assume this block and these pistons are going to the crusher. Be thrilled if either survives!

 

Regards,

 

Steve

 

 

 

 

 

 

 

 

[Dudeland]

Perhaps if you ask nicely the machine shop will extract those for you.  It likely isn't the first time at this rodeo.  They may be able to measure the pits and see what is feasible. Perhaps line boring 

 

That being said it would be very satisfying to pound those old boys out. 

 

... nice hammer. 

[Joesprocket]

This thread is giving me hope for the pistons I'm about to knock out. Thanks for posting and keep us updated with pics and progress

[02Pilot]

White vinegar, especially the strong "cleaning" variety, is your answer here. Get a few gallons and put it and the whole block in a Rubbermaid tub. Wait. Inspect. Wait some more.