Clutch started slipping on a freeway shift in OD 5th gear, quickly let off. A couple weeks later just cruising up a hill on a local highway, clutch slipped again and had to get it into a lower gear. Heres what I saw when pulled everything out. The transmission side (pressure plate side) of the clutch disc had some wear - those grooves into the lining wear material were gone but no rivets touched but there was also signs of slung "oil" (gear oil or motor oil). The engine side (flywheel) side of fhe clutch disc still had some faint signs of the grooves and there was more wear towards the outer perimeter. There was no sign of any oil and the pilot bearing showed the grease and none crawled out; the inner diameter of the flywheel was pristine clean. On the outer surface of the flywheel clearly showed lines of "oil" (gear oil or motor oil) but not really that much on the pressure plate parts - around the fingers of the plate was clean. The inner surface of the bell housing showed what looked like slung grease right in line with the area where the flywheel would sling it. The shaft for the clutch disc was clean - nothing would show on a white rag rubbed in the splines for the disc. The question is, where'd the "petro goo" come from: 1) engine main seal is leaking and gets slung out and then drips down onto the clutch.....if so why only one face of the disc? 2) pilot bearing over lubed .... nope, the inner part of flywheel is clean, really clean 3) throwout bearing .... nope if would be on the outer face and maybe get the fingers but cant reach the disc plus didnt show signs of demise 3) transmission input shaft seal leaks.....Aha! yes, maybe. But the splines for the disc were clean - passed the white rag test too - but would it get slung from the shaft and 'paint' the inside of the tube that rides inside the throwout bearing? Said tube's end could direct the "petro goo" right into the ID of the disc and could very well align with the disc to pressure plate, drips out onto the friction material, and then: a wasted clutch. Admittedly the crankshaft main seal is leaking and a new one from OEM Cummins is on hand for when the new flywheel is installed. The trans input shaft housing can be removed and a new seal installed and the shaft inspected etc etc. If this seal is the source of the leak, should I drill a weep hole to allow said petro goo to drip out the bottom of the tube instead of making it down the tube into the clutch area? The trans was rebuilt recently be a decent shop and had new bearings seals and synchros installed - there is No Play on the input or output shaft of the trans. FYI This truck is 4WD and the transfer case was removed from the trans - the transfer case has the output shaft somewhat recessed in order for the internal spline driveshaft knuckle to slide in there - but the trans has the shafts sticking out which is an arrangement that allows good inspection of the trans in and out bearings. The reason I am calling it "oil/grease" or "petro goo" is because there is no distinct odor to separate the trans gear oil from motor oil because this NV4500 has that special requirement about the lube oil so the lubricants that replace the original Castrol specd stuff that is no longer sold, and those lubricants dont have that sulfer perfume odor. Heres some pics to show these topics. As to replacement parts: New clutch kit from Centerforce with dual friction is on hand: new flywheel, bolts, press plate, disc, throwout bearing. Also new upgrade hydraulic operator system w reservoir and primary and secondary cylinders w braided hose. Will be cleaning up, then dial indicate the bell housing and then muscle the stuff back together once this leak path is hopefully eliminated.
That is not a lot of oil there. A rear main will leave a wet line below it when it is leaking much. It is your source but the other consideration is the pressure plate springs are also just getting tired. Couple that action with any friction wear and there you are.
A rear main seal, an NV5600 and a Southbend clutch kit will make that old Dodge good as new.
G56
Obvious the pressure plate was weak on one side by discoloration, but common for diaphragm type pressure plate, drive disc was also shot.
Indeed there was much wear due to slipping. But was that exacerbated by the oil/grease? And if the main seal was the source, it slung off the flywheel hit the bell housing and dripped down - but how did it only land on one side of the disc? Since but one side of the disc is oiled, and that is the pressure plate side....does that point to the trans input shaft seal......hmmm
most likely.
We had another "bright idea". Noticing the input shaft splines showed no signs of oily goo nor did the splines on the clutch hub.....we have some of that red rosin paper in a roll. We cut a piece just so and it spindled right back and then we could slide it down the input shaft and slide it around the shaft to wipe the shaft OD and also the other direction tended to undo the spindle and it wiped the ID of the throwout bearing tube. Result: clean. Maybe one little drop down by the seal on the end of the paper. A couple mechanics swear it is the rear main seal a dripping down and we arent trying to make argument, just make sure we catch the correct thing and address it, and when we say why would one side of the disc be less wetted, they agree that could be something to ponder but fix the main seal - is what they say. I will make some measurements and I am thinking that throwout bearing guide tube does Not reach far enough to allow the gear oil to drip onto the disc ..... a quick update to follow. Many thanks for the assist and thinking about this - cause I need this truck to tow tow tow and work work work. Being a 94 it is free of incumbrances like the mandated add on stuff that makes diesels a modern challenge.
Either way, the transmission had to be dropped to access either seal and the clutch. Just replace both seals. Reseal the input shaft of the trans, put in a rear main and a new clutch, and get back to work. Its one or the other, and seals are cheap compared to the labor to get at them, and then guess wrong.