Liner protrusion

[Hammerhead]

(02-22-2018 )tree98 Wrote:  What causes liner fretting anyway? Is 15 thou the magic number?

(02-23-2018 )Signature620 Wrote:  Liner movement and vibration (generally from the power stroke)

Increasing the liner protrusion to 0.015" increases the clamping force. When the head gets installed and torqued down, the head gasket crushes to final thickness to make the oil and coolant seals along with the combustion rings that contain the cylinder pressure. The increased vibration cycles, especially in 2250 and later engines with pulse injection making several bangs* during combustion increases liner vibrations. By raising the liner height the head gasket doesn't quite crush as much in the oil and coolant passages area, but still enough that the sealing isn't affected, however the liners get pushed down into the liner shelf with much more force.
The ISX is a mid-stop liner, meaning the liner is prevented from being pushed out the bottom of the block mid way down the liner as opposed to the older Cat and S60's that the liner stop was right at the top. The theory behind a mid-stop is that you are supporting the liner in two places (mid-stop and head) instead of one so it should be more stable. In the 570 & 870 with CDI combustion technology and lower static compression there wasn't enough pressure and vibration cycles to show that the OEM spec of 0.009-0.010" didn't have the necessary rigidity to stand up to the increased pressures and vibration cycles.


Using the old verbage of Suck, Squeeze, Bang, Blow to describe a four stroke engine...to describe pulse injection technology it's now Suck, Squeeze, Bang, Bang, Bang, Bang, Blow