liebherr 731c 1987 bulldozer.

Going to look at a liebherr pr 731c 1987 bulldozer and wondered if anyone knew anything about these. The guy says that on cylinder has a head gasket gone so its mixing oil & water or it could be a cylinder liner cracked if its the later can the liner be done in the machine or is it an engine out job.Are there any other things to look for that anyone has encountered on these machines.How common are the engines in these its a merc OM421 engine.


Thanks in advance.

liebherr 731c 1987 bulldozer.