rear engine main seal on mci bus

[mac1]

Will a leaking rear main seal on a mci bus cause the clutch to get soaked with oil and make the clutch slip???

[Don Fairchild]

The long and short answer is yes, If you let it go long enough you will replace the clutch when you replace the rear main seal.

Don

[Busted Knuckle]

And of course there is also a "wet clutch" set up. I've never worked on one so I can't tell ya much about them, but I'm sure some of the guru's like Clifford or older guys like Don can tell ya all about them!
  BK 

[robertglines1]

Or front seal on transmission.  Ck level in trans.  If dry set up! Pull plug out bottom of bell housing and see if there is any oil present.

[mac1]

THE reason I suspect the rear main is gone is that I had to add a gallon of oil after driving 600 kms. Then all of a sudden while I was driving, the bus quit on me, it came to a stand still. The engine is still running good. The transmission seems like it is still going in gear but the bus is going nowhere. I saw a fair amount of engine oil on the ground but I couldn't check where it is coming from. My thinking is that the oil went on the clutch and it started slipping. Does it make sense??? Should I be able to see underneath if the oil is leaking from the clutch housing   Any suggestion would be appreciated. Thanks!!!

Mario!

[luvrbus]

I believe you just lost the lining off the clutch, not knowing what model of MCI bus you have check and be sure the assist is not hung in the assist position check all the adjustments first 

good luck

[mac1]

not sure what you mean by checking if the assist is hung up and how do you check it. do you mean the maxi??

thanks!

[bevans6]

On an MCI with a Spicer 4 speed the clutch has an air assist feature that could cause the clutch to hang in the dis-engaged position.  You would be able to tell because the clutch pedal would stay on the floor.  You can see the clutch linkage if you look inside the drivers side rear engine bay door, under the alternator. 

The flywheel on the MCI is a fairly dished affair, it has a tall rim around the circumference that the clutch plates, floating plate and such fit inside of, and the cover clamps to.  It's possible for oil to get in there from the main seal, but you can be leaking pretty good and the clutch will still be dry (personal experience with my old engine that I am changing out, it was leaking a ton from the main seal and the clutch was perfect).  There is a fairly large drain slot with a scraper in the bottom of the bell-housing that is designed to catch oil slung off the back of the flywheel and direct it to the ground.

If your clutch is genuinely slipping, then I would expect it to feel perfectly normal on the pedal, but I would also expect some smoke if you let it out and tried to move, the slipping plates will heat up and burn the oil pretty good.  It doesn't happen suddenly usually, what normally happens is the engine will start revving up in high gear, like an automatic with a loose torque converter, and it will be slow away from stops, but it will still work at least a bit.

I would be looking at the clutch plates too, like Clifford says, and I would double check that it isn't the differential or an axle (is the driveshaft turning when the clutch is out?).

Brian

[TomC]

Sounds like the perfect time to switch to an Allison automatic!  Good Luck, TomC

[mac1]

Hi Guys !

Thanks for all your input. It is very informative. Does anyone knows how much it would cost to do a rear main seal and a clutch? Rough estimate please.
Thanks!
Mario!

[luvrbus]

2 to 3 grand

good luck