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Discussion Starter #1
Hi folks,

I got a 156 2.5 with 300000km on it.

The car is serviced every 10000km with oil change etc.

But the engine has never been cracked open before, and has never been rebuild.

I know that Busso engine use O-ring to seal the cylinders and the block, how long do I need to replace the O-rings?

And also, how many O-rings are used for a single cylinder?

Thanks!
 

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I would only change the O-ring if you are rebuilding the engine anyway. If it aint broke dont fix it, just dont touch or move the cylinder liners.

one o-ring pr. cylinder.

Mine failed when i had the head of and then turning the engine without the liners locked to the block. resulting in the liners to lift. i assembled the engine and at first startup, mayo in the oil....
One more time disassemble the engine, replace the O-rings and then assemble.
it can be done without removing the pistons and liners completely, but you have to be careful not popping out the piston rings because that is even more difficult to get in the liner with the piston attached in the engine.
 

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Discussion Starter #3
I would only change the O-ring if you are rebuilding the engine anyway. If it aint broke dont fix it, just dont touch or move the cylinder liners.

one o-ring pr. cylinder.

Mine failed when i had the head of and then turning the engine without the liners locked to the block. resulting in the liners to lift. i assembled the engine and at first startup, mayo in the oil....
One more time disassemble the engine, replace the O-rings and then assemble.
it can be done without removing the pistons and liners completely, but you have to be careful not popping out the piston rings because that is even more difficult to get in the liner with the piston attached in the engine.
Got it. Guess I don't need to worry about it shortly.

Just curious, are the liners easily lifted or rotate when the head is off?
 

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yes, if you turn the engine the liners will lift together with the piston. there is a special tool, but it's easily done with some pipe and washers to hold them down. I just stacked different size socket on top of eachother. do not rotate the liners ether. The o-rings are very thin. mine was also brittle when i removed them so if you are in doubt, replace them.
maybe you could do a leak test after torque down og the heads, before assembly the rest of the engine. mine leaked without pressure, so just add water through the cooling channels with a funnel.
 

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Discussion Starter #5
yes, if you turn the engine the liners will lift together with the piston. there is a special tool, but it's easily done with some pipe and washers to hold them down. I just stacked different size socket on top of eachother. do not rotate the liners ether. The o-rings are very thin. mine was also brittle when i removed them so if you are in doubt, replace them.
maybe you could do a leak test after torque down og the heads, before assembly the rest of the engine. mine leaked without pressure, so just add water through the cooling channels with a funnel.
Thanks a lot for the info!
 
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