Pitted pistons

1. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

   #1 25th October 2009, 21:17

   I've had a look at my pistons today, and noticed some damage. There are scratches down the sides of one of them where they have obviously made contact with the cylinder bore. The top edge is also uneven because of this.
   
   However, more worrying is the sides of this piston, as it is quite heavily pitted, especially round the edges of the grooves that the rings sit in. Some of the metal has 'fused' over the grooves as well in places.
   
   One of the other pistons also has a few pitts/mark on it as well.
   
   Now I'm guessing that the worst one is well and truely f**ked, but would the one which is only slightly marked still be useable? Just trying to decide if i need to go and but a full new set, as this will probably be cheaper than replacing 2 pistons plus rings
2. ryanmt Established Member Joined: Oct 2004 Warrington Posts: 1987 AX VTS 57 3.0 TDI A5

   #2 25th October 2009, 21:28

   Pics? sounds like det to me.
   Is it like this
   http://badger-5.com/bin/badgerwagen/...ton-damage.jpg
3. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

   #3 25th October 2009, 21:30

   No its different I think. Like bits of the piston have disintergrated.
   
   Think its run lean/hot. I'll try get a pic of it
4. Olly Saxperience Forum Bum Joined: Dec 2008 Meerkat Harborough Posts: 2638 Saxo vtr mk 2

   #4 25th October 2009, 21:45

   Andy one piston will be just as expensive as a set nearly. If you havent got your rings yet, maybe some wossners?..
5. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

   #5 25th October 2009, 21:46

   The worst one:
   
   
   
   
   Can just about see the damage above the top ring in the close up pic
   
   Other piston:
   
   
6. ryanmt Established Member Joined: Oct 2004 Warrington Posts: 1987 AX VTS 57 3.0 TDI A5

   #6 25th October 2009, 21:48

   I had a brillant pdf hosted on my site but i deleted it since it was getting linked on every forum under the sun. Ill post it up tomorrow. Shows detailed pictures of damage and the usual cause/solution
7. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

   #7 25th October 2009, 21:49

   Quote:

   Originally Posted by sax-oli Andy one piston will be just as expensive as a set nearly. If you havent got your rings yet, maybe some wossners?..

   Thats what I'm thinking Oli. Especially if its 2 pistons I need.
   
   Pistons are at least £100 each I'm guessing
   and rings are £100+, so thats over £300. A set of Wosners are £490 off GMC including rings etc
8. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

   #8 25th October 2009, 21:50

   You can see where the metal has fused on the first pic. The ring is now fixed into the piston
9. Thecherry0121 Established Member Joined: Dec 2008 Great Barr Posts: 1489 Cherry red 106 GTi

   #9 25th October 2009, 21:51

   ooh that would be interestin ryan as my old ones were pitted on the top im thinking either pre ign or det
10. ryanmt Established Member Joined: Oct 2004 Warrington Posts: 1987 AX VTS 57 3.0 TDI A5

    #10 25th October 2009, 21:54

    Yeah i hope ive still got it on my pc somewhere to reupload. It was a really good read, hence everybody copying it lol
11. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

    #11 25th October 2009, 21:55

    Yeah would be useful to see the pic. I'm pretty sure its from runnining lean with the boost. Previous owner Must have had the MF2 set up wrong. The scratches are deffinately from contact withthe block as the cylinder bore was marked as well
12. Sophia_Bush Saxperience Post Whore Joined: Jan 2007 Shropshire Posts: 9994 Moonstone Blue 106 GTi

    #12 25th October 2009, 22:05

    shit sorry but I wouldn't even risk it mate even if it only needed a small amoun to get right it will be in back of your mind
13. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

    #13 25th October 2009, 22:09

    Hmmmm, bugger. More money
14. Sophia_Bush Saxperience Post Whore Joined: Jan 2007 Shropshire Posts: 9994 Moonstone Blue 106 GTi

    #14 25th October 2009, 22:16

    how rough we talking on the marking Andy? If it will only take small amount of work fair enough but they look to much
    
    sorry to say it is white bread and water for a good while yet!
15. Ste Saxperience Post Whore Joined: Mar 2007 Yorkshire Posts: 5415 Saxo

    #15 25th October 2009, 22:19

    Looks to me like somethings been in the cylinder head. Maybe run a bit lean and melted the plugs or bits of them!.
    
    Not sure if its the pics, but if it was heat damage that effected the pistons the pistons would have literally melted down the 'scratches'. Hard to describe but almost like a mini lava flow had passed through each scratch.
    
    That looks like its dragged some debris up and down for a few seconds.
16. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

    #16 25th October 2009, 22:21

    Arsecakes. Hate bread and water.
    
    Worth going oversized again?
17. Ste Saxperience Post Whore Joined: Mar 2007 Yorkshire Posts: 5415 Saxo

    #17 25th October 2009, 22:22

    Quote:

    Originally Posted by Andy_K Arsecakes. Hate bread and water. Worth going oversized again?

    
    Depends on the head damage, but as usual with the little monsters to be safe.........
18. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

    #18 25th October 2009, 22:24

    Quote:

    Originally Posted by Ste Looks to me like somethings been in the cylinder head. Maybe run a bit lean and melted the plugs or bits of them!. Not sure if its the pics, but if it was heat damage that effected the pistons the pistons would have literally melted down the 'scratches'. Hard to describe but almost like a mini lava flow had passed through each scratch. That looks like its dragged some debris up and down for a few seconds.

    Know what you mean. Strangely the bolts on the crank cap on that cylinder were very tight compared to the others. I wonder if they had been overtightened and the piston had skewed in the cylinder so it could touch the sides maybe?
19. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

    #19 25th October 2009, 22:25

    Quote:

    Originally Posted by Ste Depends on the head damage, but as usual with the little monsters to be safe.........

    Using a newer bottom end. Just it would be wanting honing anyway, but worth a slight overbore instead. Virtually no difference in cost