Southern Pa. | hogman_2002 - 12/11/2018 22:34
Pardon my ignorance, but how can a liner "drop down".
The liner sits in the counterbore of the block. The counterbore could be cut improperly from day one, allowing the liner to sit low. In this scenario, not enough "crush" is put on the head gasket on this cylinder. After a time, the head gasket will fail. This can be remedied by shimming the liner to proper height. Liner height is supposed to be checked during initial engine assembly, and at any overhaul. Also you have manufacturing tolerances. Potentially there could be a "thinner" liner set into a lower counterbore, or vice versa. If a liner on the low side of tolerances is sitting beside a liner on the high side of tolerances, that'll be problems for sure. Also counterbores aren't always cut properly due to manufacturing defects, and (even though the liner height may check ok) the liner may be merely sitting on a couple high spots, and not seated solidly. This can cause the liner to "settle" after a time, causing head gasket failure.
Cutting the counterbores properly, and then shimming the liners to the proper height should remedy these issues.
It all comes back to quality control during manufacturing and initial assembly. Somebody wasn't paying attention. |
Deere 13.5L head gasket
