Topic: piston ring removal

[taymoor]

I have a 72 cb350f and here is one of its pistons.  I have new rings on it, but I can't figure out how to remove the old ones without damaging the piston.  I've already ruined one piston trying to get on of these out.  Also, should they be this tightly embedded?

[taymoor]

here is another pic, not that its so different from the first

[mystic_1]

Piston ring expander.





mystic_1

[taymoor]

on that first pic you can see how deeply embedded the ring is in the land.  Will an expander be able to get to the rings?  I'll go check it out at a parts store tomorrow.

[mystic_1]

Those look fairly normal to me, unless I'm missing something?

Use Easy Off oven cleaner and a brass brush to remove some of the carbon, that may help.  Note that oven cleaners react with aluminum so don't leave it on there overnight.

Pry the ring gap open a bit, which will cause the ends of the ring to stick out a bit.  Then clip on the expander, squeeze to stretch the ring open, while using your other hand to steady the other side of the ring.  Finally, lift the ring straight up off hte piston.  Don't let the piston twist when you expand it.

How did you ruin the one piston, it it gouged?

mystic_1

[taymoor]

The rings are so tightly embedded in there that I got a set of picks and hooks to get it out, and the ring gaps still won't open up.  To see how I ruined another piston, please refer to one of my other posts at   http://forums.sohc4.net/index.php?topic=49837.0      Just today, I was told by a neighbor that the piston is still good with the chip in it.  What do you think?

[Burnboy]

yeah I would soak them in something and it should releas the rings a bit

[mystic_1]

For sure.  The rings look normal to me, but there's a ton of varnish and crap holding them into the ring grooves. You need to break that stuff up.  Soak it in Acetone mixed 50/50 with transmission fluid, that's supposed to be the magic penetrating formula.

Sadly the one chipped piston is no longer usable, particularly given the location of the damage.

mystic_1

[bryanj]

Those rings are stuck down in the grooves and should sit "proud" and springy.

Soalk the pistons in boiling water might loosen enough to pry the gaps open, dont burn youre hands tho'

Or leave in a penetrating mix for a while but nothing caustic

[mystic_1]

Yup, that's what I meant.  I should have said "look normal to me except for being stuck down in the grooves." 

mystic_1

[05c50]

If you haven't got the rings out yet, try soaking the piston in combustion chamber cleaner. It worked for me. Heat the piston up (on the grille outside?!!), put it in a metal container,spray on the cleaner and let it soak for an hour or so. The stuff breaks up carbon and frees up the rings.

......Paul

[Frankencake]

If worse comes to worse, I've got a 350 motor that turns over, for sale.
I'm having the same problem with a few 550 pistons.  I used heat on the last one I did.  I just let the torch heat the top of the piston and then I went at the ring gap with a dental tool.  The ring came out in pieces but it's out and I can still use the piston.  Take your wrist pin out first.  (learned the hard way)  Can I still use it if it's blue?

[mystic_1]

If it's blue, the metal (or coating if it's hard chromed) has changed it's chemical composition.  I'd replace it rather than risk a broken wrist pin 

mystic_1

[Frankencake]

If it's blue, the metal (or coating if it's hard chromed) has changed it's chemical composition.  I'd replace it rather than risk a broken wrist pin 

mystic_1

Thanks.  That was quick.

[taymoor]

thanks, I'll try heat and soaking and see if those work.  I'll let you all know what the end result is!