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Question with my piston

  #1  
Old 05-23-2018, 05:03 PM
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Question with my piston

After being cleaned!
The pin that goes through, itís sort of stuck with the connecting rod! Is that normal?
I thought the piston should ride smoothly on that pin but it seems that the rod is moving along with the pin.
I did a search and it seems that in order to remove it? It needs to be heat it? I donít have a press to remove it.
Iíve seen videos when people repack it they would used assembly grease but if heats needs to be apply to install it would be melted!

how loose the piston needs to ride on the pin or spins with it as one piece?

right now the connecting rod spins with that pin as of one piece!

i hope you understand what Iím trying to say😳

 
  #2  
Old 05-23-2018, 06:18 PM
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I've got Mahle Motorsport replacements for the Cooper . Better pin and much better piston strength than the stock cast ones. They also come with some killer rings. Let me know if you need them
I have a sale on them.
 
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  #3  
Old 05-23-2018, 07:52 PM
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Originally Posted by gum View Post
After being cleaned!
The pin that goes through, itís sort of stuck with the connecting rod! Is that normal?
I thought the piston should ride smoothly on that pin but it seems that the rod is moving along with the pin.
I did a search and it seems that in order to remove it? It needs to be heat it? I donít have a press to remove it.
Iíve seen videos when people repack it they would used assembly grease but if heats needs to be apply to install it would be melted!

how loose the piston needs to ride on the pin or spins with it as one piece?

right now the connecting rod spins with that pin as of one piece!

i hope you understand what Iím trying to say😳

This may be out of my league here. I learnt all my auto wrenching from myself, and books in the library.

There are a few methods in which the piston, wrist pin, and con rod are secured together. Some older motors utilize a circlip on each end of the wrist pin to keep it in place. I infer newer motor design tend to rely on interference fit between the wrist pin and the small end of the con rod. From the photo the Mini must fall into the latter. Obviously you will need a good hydraulic press to press out the pin. By this I exclude the bench top toy press HF sells.

May be the retired tool and die maker with extensive heat treating experience can chime in.
 
  #4  
Old 05-23-2018, 08:27 PM
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I saw in YouTube that I would need a torch to hit the rod by the wrist pin then extract it. or taken it to a machine shop; but my worry is that the rod is sort of stuck on the wrist pin and when it swivel as one unit together the rod and wrist pin so, itís spinning on the skirt of the piston.

may be there is a builded up of dirty stuff in there, the piston are good itís a shame replacing them, I would look for a cheaper alternative which is cleaning them and lube them and see if I could get them move as they should.
 
  #5  
Old 05-23-2018, 08:33 PM
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If I have not mistaken on the Mini con rod. Interference fit means they are practically fused together as one, as intended by the design. Hence the wrist pin only swivels about the piston bores. Unfortunately when it comes to this kind of work, Bentley manual is less useful than a roll of toilet paper.
 
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  #6  
Old 05-23-2018, 08:45 PM
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Yes I do have the Bentley manual and I agreed with you!

woa I didnít know that, how can I improve that stiffness? It is worthy doing it or just put the new rings back after honing the walls?

every day I learn something new:

tks
 
  #7  
Old 05-25-2018, 07:57 AM
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I’m getting ready to do some pistons(walls) honing since I have the pistons out on cyl 1&4 then I would do 2&3 cyl, I m doing it while the engine is mounted.

thinking ahead to break the engine I’ve read that I should no used synthetic oil? Is it right to do this?
The reasons being that it would prevent the rings to properly fitting with its cylinder walls!

 
  #8  
Old 05-25-2018, 08:03 AM
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Sound to me like hog wash advise - not the synthetic oil on the freshly honed cylinder walls.
 
  #9  
Old 05-25-2018, 12:10 PM
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Cylinder block, much better lol I’m not a mechanic as you can tell
 
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