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After repairing my engine I thought I might cut up one of my cracked pistons to see how bad the crack was and if there was a fault in the casting.
I put some pictures of the rings in as well, you can see at 100 000 Km they are showing stuff all wear. These engines should do 400 000km a peace of piss if the pistons will hold together.
You can see from mine that it was only a matter of time before it cracked clean into the oil gallery and blew a hole in the piston. the oil cooling gallery is coloured in blue, on the bottom of the piston you can see the oil squirt hole arrowed and the oil return circled and smaller arrow.
A mate has just bought a 2000 Gu with the older block and a blown piston. it has a crack in the same spot as mine. he is going to rebuild it with all after market stuff which will give him a pretty cheap car. I don't think he is even going to bother with the upgraded block.
I reckon the crack is heat related, my No 1 &4 pistons were cracked in exactly the same spot. I will do everything to control exh temps I can and see what happens.
Not sure if the moderator can make my pictures bigger or let me know how to get them bigger so you can see the cracks properly.
This is just for educational value and I needed practice with the hacksaw :p
 

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Discussion Starter #4 (Edited)
Righto here are the pictures at a decent size I hope this works

This shows the crack on the engines front side extending down from the crown


The shiny mark on the surface of the piston ring shows the wear area that has been polished smooth.


These are the holes in the bottom of the crown, the larger one with the blue arrow should be where the squirter puts the oil in. the other smaller hole is a drain as are the small holes that have been circled.



This is the number two piston ring and you can see that it is worn less than the top ring as it is not subject to the same pressures as the top ring.



This is the outer part of the piston and you can see how the crack was very close to or into the piston cooling gallery (blue) it was only a matter of time before I blew a hole in the piston.



The last picture is of the crown and you can see how I cut down through the middle of the crack on the front side of the piston. the 4 scratches denote #4 piston.

Bloody wife changing files around lol
 
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well that was ****, I used the image code on photobucket. Some help please!
 
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Cheers Yom, :bananaro: Your blood is worth bottling.
 

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This shows the crack on the engines front side extending down from the crown




The shiny mark on the surface of the piston ring shows the wear area that has been polished smooth.




These are the holes in the bottom of the crown, the larger one with the blue arrow should be where the squirter puts the oil in. the other smaller hole is a drain as are the small holes that have been circled.





This is the number two piston ring and you can see that it is worn less than the top ring as it is not subject to the same pressures as the top ring.




This is the outer part of the piston and you can see how the crack was very close to or into the piston cooling gallery (blue) it was only a matter of time before I blew a hole in the piston.




The last picture is of the crown and you can see how I cut down through the middle of the crack on the front side of the piston. the 4 scratches denote #4 piston.

Sorry!
 

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..............d`oh!!!!!



:(
 

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Very good thread and worth a bump!!
I can guarantee if you had cooling issues resolved those pistons could go another 200k
A lot of small cracks can be stress, age related marks but overheating can cause dramatic cracks fast or lack of oil flow.
Which year Patrol was this piston from??
I have just posted a thread on the very same topic.
I bought an early failed engine 2000era engine one of the first water cooled turbo version just to tear it down, strange thing and unusual was the head was mint but bottom end was scrap with two of the pistons cracked also!!
Even stranger was that No 2 and 4 were like new!
 
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