Have started the process of possibly pulling the engine from our D5C Hystat- looking for the cause of a significant oil leak at the back of the oil pan area. The oil pan bolts are tight- when running, there is a wide broad oil leak the full width of the back of the oil pan. Will a bad rear main seal actually leak at the back of the oil pan area? Everything is dry topside on the engine. The leaking oil comes right at the back of the pan and runs down the full width of the bellhousing. Definitely engine oil , not hydraulic oil. Oil pressure about 45 psi cold, and drops off to 15-20 when warm. Will a bad rear main seal cause any loss of oil pressure? Can the Oil Pan gasket be changed with the engine in place, or does the engine have to come out? What are the main signs of a blown rear main seal on this engine? Still deciding whether or not to pull the engine- big job working by myself. Started this post separately as my other post was about pulling the engine. Thanks for any help.
Nobody responded to my post, but just in case anyone was curious about the problem- I went to a local Holt cat tech rep and he suggested that the leak is not the rear main seal, but rather there is a gasket between the bellhousing and the back of the engine block- he says the gasket can fail and the bellhousing bolts can loosen and then oil will stream down the gap between the back of the oil pan and the bellhousing-- even so, I still have to replace the rear main seal as I will have to pull the flywheel and bellhousing to get back to that gasket area.
Well thanks for the update and sounds like you got the answers you need. Not sure if your pulling the engine or pumps to get at it but I have done quite a few D6K hydrostatic eng to pump couplers and it was easier to pull the engine. Support the pumps from below with a jack and leave the pumps and 50 lines all in place. The rad/hardnose was only a handful of bolts and engine super easy to pull and very few connections to undo. Less than 6 hrs from running to engine out. Not sure about the D4C. If the rear of the oil pan bolts into the flywheel housing your best to pull the engine entirely (if the pan can't come out in place) as your going to disturb the oil pan gasket when you pull the rear housing and odds are it will leak after! I would do the rear seal, block to flywheel housing seal and oil pan seal in this case. Have a good look at the pump coupler as well And back to your first post - no a rear seal leak will not cause significant oil pressure loss unless it gets pushed out entirely. If you loss oil pressure due to an external leak it will be spraying out not running out
Sounds just like 3408/3412 in D9/D10. The rear gear train housing holding bolts would loosen on those engines and cause an oil leak all over the rear end of the engine. The difference on those machines was that a failed rear crankshaft seal would cause oil to leak into the torque converter housing as opposed to falling on to the ground.