wrist pin stuck in piston

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K

Kez

Well-Known Member
Joined
Feb 27, 2003
Messages
1,230
Have a K&B 7.5 OB in storage years ago. I loaded the case with MMO before I put it away. Everything looked good with smooth bearings etc. but the wrist pin is now stuck in the piston from the castor oil that gummed up.

Because the K&B piston has a closed end, there is no way to push the pin out. The small end of the rod rotates freely on the wrist pin. I am thinking to run it as is and hope that the heat will free up the pin. Anything thoughts or suggestions?

Thanks,

kez
 
Hey Kently, Equi used o use the MMO as a locktite since it would actually evaporate over time it worked very good and never left any residue.
 
Last edited by a moderator:
bzubee said:
Hey Kently, Equi used o use the MMO as a locktite since it would actually evaporate over time it worked very good and never left any residue.
Click to expand...
Are we talking about Marvel Mystery Oil? MMO? If so , I would run the engine to temp.if possible, that should loosen up

the internals to get it apart. I put mine in trans.fluid for storage.
 
Last edited by a moderator:
Hot soapy water and a strong magnet while working the conrod has worked for me on stubborn K&B wrist pins.
 
See if you can gently start a tap in the hollow of the wrist pin for pulling. The tap and wrist pin will be hard material so do not use a lot of force or things will chip. If you can get the wrist pin to turn, your half way there. Keep it wet with penetrating oil also while doing this.
 
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Run it, or soak it hoppe's #9 Nitro solvent (gun cleaning solvent), or the crock pot on low with cheap green antifreeze in it for a few hours. other antifreezes seem to darken the aluminum, & don't clean as well. if you've never cleaned nitro engines this way, try it - you will never do it another way! thanx , jetpack for this cleaning trick.
 
moparbarn said:
Run it, or soak it hoppe's #9 Nitro solvent (gun cleaning solvent), or the crock pot on low with cheap green antifreeze in it for a few hours. other antifreezes seem to darken the aluminum, & don't clean as well. if you've never cleaned nitro engines this way, try it - you will never do it another way! thanx , jetpack for this cleaning trick.
Click to expand...
I can verify that the orange Dexcool antifreeze does not work with a flip. A total waste of time. Will use the green Prestone kind the next time.
 
The newer yellow/gold organic antifreeze is just as bad. the old basic green works the best, & that is excellent. throw in the engine or parts, let marinate on low for a few hours, remove & rinse - done. clean down in every crack & crevice. about as painless as it gets. a small fryer basket or strainer to put the parts in makes it easy to get them out of the hot antifreeze. don't let the parts cool in the antifreeze, some deposits will harden & not rinse off as easily. all lessons learned the hard way.........
 
Thanks all for your suggestions. I am wondering if running the engine with the wrist pin stuck in the piston will harm the engine in anyway. I can't think of any reason...unless I miss something obvious. I would not run the engine if the wrist pin is stuck in the small end of the rod.

I am also thinking that heat and stress from running the engine will un-stuck the pin

Thanks,

kez
 
I have personally used MMO to dip my head bolts and others to lock tight them. There is a shalack (spelling) in the MMO or something that will harden when heated and have done this for about 10 years now with out a bolt backing off. Everytime i tighten them to spec and then try to loosen after running the engine there is that (crack ) sort of sound like a tight bolt should be with out over tightening. Just a FYI

Jeff
 

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