[Bagshot]

Morning all, probably pushing my look for a long distance diagnosis, but here goes anyway. Original symptoms where a knocking at the top rear of the engine and smoking heavily on acceleration, resulting on a tow home to make sure, just in case. First diagnosis varied from piston slapping, broken injector, damaged valve or valve spring With now the head off no damaged valves I can see straight away,(though the head is going off for testing and valves recut if needed) but, all piston tops are clean with just s light carbon film that cleans off..however..No 6 at the back, where the noise seemed to come from is damp and has what looks like small peck marks all over the crown.
Broken piston rings anyone..?
And.. Pull the piston out from the top or through the bottom, if so anyone pulled these before .?

 

[jamesmartin]

piston will come out the top, its had something in the cylinder if piston top is marked, its worth pulling it out and checking

 

[Bagshot]

I was hoping it was through the top, cheers.
In addition.. If rings, do one set do them all..??

 

[jamesmartin]

I was hoping it was through the top, cheers.
In addition.. If rings, do one set do them all..??

generally you buy a piston set so a 6 pot would need 6

 

[Bagshot]

generally you buy a piston set so a 6 pot would need 6

Seems obvious really... Cheers.!

 

[Wazzajnr]

If it's wet, it might just be the injector putting too much fuel in.
Would have been nice to do a compression test before the head came off.

 

[brianp38dse]

If the rings have gone there would be marks in the bore and for it to do anything to the crown of the piston it would need to take a chunk out to get up there, I would think some metal item got in through the inlet, was the head marked as well.

 

[Bagshot]

If the rings have gone there would be marks in the bore and for it to do anything to the crown of the piston it would need to take a chunk out to get up there, I would think some metal item got in through the inlet, was the head marked as well.

No, the head from first inspection (!) looks pretty clean with just slight carbon on the face of the valves. Just seemed odd that the other 5 crowns are almost wipe clean, but this one is not so healthy.
Thanks to everyone here, I appreciate its difficult without seeing it, so I'll stick a picture on next

 

[Bagshot]

No, the head from first inspection (!) looks pretty clean with just slight carbon on the face of the valves. Just seemed odd that the other 5 crowns are almost wipe clean, but this one is not so healthy.
Thanks to everyone here, I appreciate its difficult without seeing it, so I'll stick a picture on next

Pics, first one is pot

No 1, second one is the offending article..

 

[jamesmartin]

Pics, first one is pot View attachment 133493 View attachment 133494 No 1, second one is the offending article..

not easy to see but the offending one looks more like water damage, need a few better pics to be sure

 

[brianp38dse]

That does not look like mechanical damage, may be over fuelling, it looks much wetter round the piston bore area.

 

[Bagshot]

Hi All, these might help more..