Stuck piston

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Robert Luland
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Stuck piston

#1

Post by Robert Luland » Thu Jul 01, 2010 7:28 pm

Got a question for you gear heads. I know this has nothing to do with Harley but I'm going to ask it any way. We scored a restoration project for my 14 year old son, a 1967 Honda CT90 with 800 original miles on it. It hasn't been run since the early seventies and the piston is seized from sitting. I was going to hang vertically and put some penetrating oil down the plug hole and see if I get lucky. Any one got a better idea? This has got over head valves and I sure would like to avoid pulling it apart due in part to the fact that I don't have the ninety-five special tools that the land of the Rising Sun required then. Thanks Guys, Bob



steinauge
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Re: Stuck piston

#2

Post by steinauge » Thu Jul 01, 2010 7:46 pm

That was a really good little engine.You cant run one to death,you have to kill it with a stick. :) The penetrating oil is a good idea.I would add some heat from a heat gun.Get the cylinder good and hot and rock the crank back and forth by the flywheel,repeat until the piston comes loose.Best of luck.

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Re: Stuck piston

#3

Post by shooter15 » Thu Jul 01, 2010 10:19 pm

Robert Luland wrote:Got a question for you gear heads. I know this has nothing to do with Harley but I’m going to ask it any way. We scored a restoration project for my 14 year old son, a 1967 Honda CT90 with 800 original miles on it. It hasn’t been run since the early seventies and the piston is seized from sitting. I was going to hang vertically and put some penetrating oil down the plug hole and see if I get lucky. Any one got a better idea? This has got over head valves and I sure would like to avoid pulling it apart due in part to the fact that I don’t have the ninety-five special tools that the land of the Rising Sun required then. Thanks Guys, Bob
I had a '61 VW that had a stuck engine....I tried everything from penetrating oil to dragging it around in low gear behind a car tring to free it up,nothing worked......a friend of mine told me to try anti-freeze,told me it was "thinner" than oil and he had used it with good results.....I filled all 4 plug holes and let it sit for a few days....hooked it up behind a car and popped the clutch in low gear.....it freed up easily with out any damage........I've used it on many stuck engines since with the same results....just give it time to seep in........"SHOOTER"

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Re: Stuck piston

#4

Post by awander » Fri Jul 02, 2010 12:29 am

On old tractors, the usual recommendations are kerosene, or ATF. Sometimes a mix of ATF, acetone, and something else I can't remember right now.

james
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Re: Stuck piston

#5

Post by james » Fri Jul 02, 2010 1:10 am

Dump some Kroil in the plug hole and let it creep for a few days.

Jim

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Re: Stuck piston

#6

Post by FlatHeadSix » Fri Jul 02, 2010 2:49 am

james wrote:Dump some Kroil in the plug hole and let it creep for a few days. Jim
You beat me to it Jim, Kroil is amazing stuff and has worked for me on some pretty impossibly stuck things. Its pricey but you don't need much, and it works where other things will not.

But then again I've heard about the antifreeze trick too....

mike

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Re: Stuck piston

#7

Post by awander » Fri Jul 02, 2010 3:19 am

Kroil is good stuff. Yesterday, I was installing atrailer hitch on my (new but old) Jeep. I had to remove 4 bolts and 4 nuts that had been on there since 1997, and on the the right side, I was sweating it.

Halfway through, I got the Kroil out and gave a quick squirt to each of the bolts/nuts. I watched it creep right into the joints. Half an hour later, i was done withe right side. I moved on to the left side, and the nuts and bolts basically came out as if they were new-after letting the Kroil work for half an hour.

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Re: Stuck piston

#8

Post by Sir_Rat » Fri Jul 02, 2010 12:45 pm

I've seen this used to free up blocks that got submerged in salt water...it works....oil of wintergreen!!
smells good too ...good luck :D

Aloha...Mike

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Re: Stuck piston

#9

Post by Kuda » Mon Jul 05, 2010 12:44 pm

Robert Luland wrote:Got a question for you gear heads. I know this has nothing to do with Harley but I’m going to ask it any way. We scored a restoration project for my 14 year old son, a 1967 Honda CT90 with 800 original miles on it. It hasn’t been run since the early seventies and the piston is seized from sitting. I was going to hang vertically and put some penetrating oil down the plug hole and see if I get lucky. Any one got a better idea? This has got over head valves and I sure would like to avoid pulling it apart due in part to the fact that I don’t have the ninety-five special tools that the land of the Rising Sun required then. Thanks Guys, Bob
Kroil, without a doubt. I buy it two ways, in a spray can for hard to reach stuff and a 1 pint can for things like stuck pistons. I use about a 1/8 cup in the cylinder, let it sit for a day or so, then use a rig I made up using a compression tester adapter and an air line fitting. Loosen the rockers/pushrods to close the valves, then start with about 20 pounds, then gradually increase until the engine turns over. Hasn't missed yet. Even worked on a big block 390 Ford motor with all four right side pistons stuck from a leaking headgasket (and 20 years of sitting). Good luck,

-Kuda
'49 panchop

jason.weir
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Re: Stuck piston

#10

Post by jason.weir » Thu Jul 08, 2010 3:31 pm

Sometimes all the penetrating oil & heat tricks just don't work - this always does - cut up a spark plug and drill and tap for a grease fitting, fill the cylinder with oil and then install the spark plug adapter and use a grease gun to apply pressure on the piston. On really stuck ones, I've seen a porta-power used to generate lots of hydraulic pressure. They always pop free and really smoke for a while after you get it running. If your lucky the smoking stops..

-J

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Re: Stuck piston

#11

Post by Bosheff » Thu Jul 08, 2010 4:43 pm

The grease gun trick also works very well to free stuck disc brake pucks when tilted/cocked/stuck in the bore. Also works excellent for removing pilot bearings/bushings from cranksahfts in automotive applications....bosheff

Robert Luland
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Re: Stuck piston

#12

Post by Robert Luland » Thu Jul 08, 2010 11:06 pm

Good day lads. I figured I chime in and give ya and update on operation soy sauce. The penetrating oil and heat didn't work. After thirty-five year in hibernation. That puppy is stuck in there. We conceded to pulling the top end off next week and beat the ever living piss out of the thing! Below see a picture of my dedicated ground crew hanging the carcass. I'll keep ya updated. Bob L
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Re: Stuck piston

#13

Post by john HD » Fri Jul 09, 2010 12:43 am

fine looking pair of lads you have there bob!

do not forget to include pictures of the hammer!

john :D

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Re: Stuck piston

#14

Post by steve_wood » Fri Jul 09, 2010 2:27 pm

Bob:

Nice looking shop! Wish I had that much room.

On a more serious note, you might want to re-consider the brute force method. I had a topper with a stuck piston and the brute force method destroyed the piston and damage the surrounding parts as well.

The hydraulic method looks very cool - and it seems powerful. Have you tried that method yet?

Bosheff
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Re: Stuck piston

#15

Post by Bosheff » Fri Jul 09, 2010 3:01 pm

If the piston has to be sacraficed, so be it. I would rather waste the slug than the cylinder, although the jug will probably need to be bored anyway. If possible I would have a replacement piston in my possession before starting the teardown, being careful not to damage the cylinder or the connecting rod. If another cylinder was available, I'd grab that up too. Ideal situation would be to have a cylinder and piston of known dimensions before demo begins. A spare engine would be the ultimate....bosheff

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