this one just came in yesterday, no history 2005 seriel#1562 pc78mr--6 5360 hrs yanmar or komatsu s4d95le-3 engine. there is engine oil leaking out of the middle of the starter drips bad enough that it needs fixed, owner before has put rubber red silicone on the bell housing joint, and installed a air coupler on the bottom of bell housing plug. is this a wet hole flywheel set up or is it just a mechanic who did not install the rear main properly trying to find the leak. if this is a dry hole setup would the lovejoy/dampener need replaced since its probably been in oily conditions?
also looks like there is a breather tube canister setup on the top side of the bell housing, if this is plugged would it cause higher then normal pressures in the bell housing
I have not had a PC78 apart before but Komatsu generally runs a wet damper case. If it is a wet case you will be able to look at the damper case under the pump and see a plug about a half an inch from the bottom of the case. If it is there you can remove it and there should be little to no oil come out of it. If there is a lot of oil you will know that oil is leaking in. It can come from the rear main seal on the engine or the front seal on the input shaft for the pump. On the larger machines I would replace both of them. Here is a video showing older Komatsu excavators and their maintenance. These machines use a pipe plug for the level instead of a cap plug but the procedure is the same. Good Luck!