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Apr 29, 2010 17:38:02 GMT
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ive got a old polo engine I'm cleaning up before fitting,bought untested but was a "good runner " suposedly
anyway ive been cleaning the piston CROWNs up today , i noticed the pistons move a slight amount in the bores ....didnt really expect them to tbh
is that normal for some slight slight movement on a used engine or no
the bores look fine with no step or socres etc
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91 golf g60, 89 golf 16v , 88 polo breadvan
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nutter81
Part of things
I joined facebook so i could talk to the missus
Posts: 928
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Apr 29, 2010 17:40:23 GMT
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sounds like the big end bearing
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Apr 29, 2010 17:46:11 GMT
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sounds like the big end bearing whys that? |
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91 golf g60, 89 golf 16v , 88 polo breadvan
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Apr 29, 2010 17:51:59 GMT
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How much movement is there? Are they rattling round in the bores or is it only measurable with a feeler gauge?  |
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Apr 29, 2010 17:54:30 GMT
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deffo not rattling around , just visible to the eye ..
i just assumed they would be rock solid and not move at all
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91 golf g60, 89 golf 16v , 88 polo breadvan
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Steve
Posted a lot
Making progress in small, easy to handle chunks of awesome
Posts: 2,028
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Apr 29, 2010 17:55:28 GMT
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sounds like the big end bearing Might be that the engine in question has a floating type gudgeon pin which will allow the piston to move side to side. One way your gonna be able to tell if there is any unusual wear is to take the pistons out, remove the rings then put them back into the bores and measure the gap.....but don't know if there is a set measurement for new rings in any book  |
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Apr 29, 2010 18:00:39 GMT
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You should be able to move them side to side a little bit, because the rings will be a little worn and the crank will allow them to move in that direction. If you can move them front to back then the gudgeon pin in the piston or the big-end bearing is worn, which is not such good news.
If they are really slack then the rings are too worn, but a bit of movement isn't anything to worry about. While you've got it apart you could always replace the rings though, should only be about £35.
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Apr 29, 2010 18:00:48 GMT
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Its normal even on a new engine to have side to side movement, the piston rings are springy, and when on the piston (out of its bore) they are loose. This is why a ring compressor is used to get the piston into its bore. Once it is in,the rings will allow the piston to move about . Serious big end wear would give you up and down movement........on a polo, I cant see you are going to have any issues unless its been to the moon and back on a daily basis for the last 10 years. :-)
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nutter81
Part of things
I joined facebook so i could talk to the missus
Posts: 928
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Apr 29, 2010 18:20:31 GMT
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sorry i thought it was up and down movement not side to side my old mini had up and down and it was the bearings ill get me coat
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Apr 29, 2010 18:31:48 GMT
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Lol.
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Apr 29, 2010 18:59:34 GMT
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deffo not rattling around , just visible to the eye .. I just assumed they would be rock solid and not move at all The clearances improve as the engine heats up. Cold, it'll have a bit of movement, especially if you've taken the rings off and have the piston in the bore by itself. Excessive movement usually shows up as scored bores on the thrust face, I think? --Phil |
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Apr 29, 2010 19:14:07 GMT
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right cheers all sounds fairly normal then...i wasnt too sure not sure i can re ring it that cheap , its vw only as far as i know , the big bolts are near £5 each with the vat on  didnt ask about rings |
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91 golf g60, 89 golf 16v , 88 polo breadvan
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didnt ask about rings