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| Question for the good Brains here https://www.ausmini.com/forums/viewtopic.php?f=2&t=70356 |
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| Author: | TK [ Tue Apr 26, 2011 7:13 pm ] |
| Post subject: | Question for the good Brains here |
After 2000K of driving I have pulled down my 1275 to find the big end Journel on number 2 conrod has a problem. The side faces of the rod journel have been rubbing excessively on the crank resulting in Blue heat marks and a bur that has been thrown up on the cap. This can all be seen in the Photos Below The Crank is unmarked. Any suggestions as to what may have caused this please Guys? Thanks, TY 
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| Author: | drmini in aust [ Tue Apr 26, 2011 7:17 pm ] |
| Post subject: | |
Bent rod is my first thought... Crank is harder than the rod, that's probably why it's unmarked. |
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| Author: | GT mowog [ Tue Apr 26, 2011 7:21 pm ] |
| Post subject: | |
Post up a pic of the piston skirt. <EDIT> I doubt it's a bent rod, it has rubbed in the wrong places, actually looks more like dirty assembly. |
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| Author: | drmini in aust [ Tue Apr 26, 2011 7:29 pm ] |
| Post subject: | |
I'm also wondering why it's not scored further round? Is the cap on crooked? ie dirty as GT says, or cap mismatched? How does the other side look? |
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| Author: | TK [ Tue Apr 26, 2011 7:40 pm ] |
| Post subject: | |
Here you go. 
The side of the Skirt showing the wear is on the opposite side to the wear on the rod! Thanks, TY |
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| Author: | TK [ Tue Apr 26, 2011 7:44 pm ] |
| Post subject: | |
drmini in aust wrote: I'm also wondering why it's not scored further round? Is the cap on crooked?
ie dirty as GT says, or cap mismatched? How does the other side look? Kevin, Other side looks fine and normal. Cap is original off rod. TY |
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| Author: | simon k [ Tue Apr 26, 2011 7:47 pm ] |
| Post subject: | |
wierd how the bearing isn't damaged from the rod distorting.... did the rod 'belong' to the crank, or were they put in the same motor recently? |
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| Author: | GT mowog [ Tue Apr 26, 2011 7:48 pm ] |
| Post subject: | |
Not a bent rod. Either dirty assembly, the bearing shells and piston skirt also tell this same story or possibly as the Doc has also suggested, mis-matched caps. Is that the only one like that? |
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| Author: | TK [ Tue Apr 26, 2011 8:01 pm ] |
| Post subject: | |
Rods Did not "Belong" to the Crank. It is just the one Like it. Note that the rod also has Blueing from heat .... TY |
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| Author: | Convertible Mini [ Tue Apr 26, 2011 8:47 pm ] |
| Post subject: | Looks like.. |
There is a possibility there that at some stage the rod has been resized and when they cut the faces they were not faced square and the side of the rod circle is now not Flat. This usually happens if the rod is slightly bent. You will find that one side is leaning the opposite to the other. Taking a light cut off the side of the rod will normally fix that to square it up. But check the wear marks on the piston first. You are not using a 12G1505 stroked crank by any chance ? |
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| Author: | VulcanBB18 [ Tue Apr 26, 2011 8:51 pm ] |
| Post subject: | |
What prompted you to pull the motor after 2000kms? Did you get the rods resized? It almost looks like the journal was too big for the rod??? strange. cheers,' Jacob |
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| Author: | TK [ Wed Apr 27, 2011 8:59 am ] |
| Post subject: | |
Not a stroker, I pulled it down as the gearbox that I was using had a crook second gear. I had the box rebuilt and though that I'd check on the enginebefore putting it back together. |
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| Author: | VulcanBB18 [ Wed Apr 27, 2011 1:08 pm ] |
| Post subject: | |
Sorry, didn't mean to suggest it was a stroker, was more interested if the rods were measured & resized to suit the journals or if the engine was assembled "as is"? Cheers Jacob |
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| Author: | TheMiniMan [ Wed Apr 27, 2011 3:17 pm ] |
| Post subject: | |
there are obvious signs of grit in the bearings, only small amounts of tiny stuff but still, it`s there The side clearance on the rods/bearings is not enough for the journal width, hence the heat-blue, check the rods are centered correctly to the bore & crank journal & i`d check the gudgeon-to-piston tightness, looks like you may have then a little to tight maybe? |
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