Replacing a Rear Main Seal on a T3 - Thoughts?

[GuzziChris]

Asking this for a friend who has a T3 in need of a rear main seal. Couple of questions for anyone who wants to chime in:

- Can an amateur of average wrenching skills even contemplate this task?
- What would be an average shop charge (in hours) for labor? 10? 15?
- Aside from the obvious oil leak and keeping the levels topped up, if it's not leaking badly is there any downside to just riding as is, assuming it's not spewing oil heavily?

Thanks in advance.

[blackcat]

- Can an amateur of average wrenching skills even contemplate this task?

Yes.

- What would be an average shop charge (in hours) for labor? 10? 15?
If he doesn't want to burn up a lot of cash, I'd suggest he takes his average wrenching skills and pull the engine and deliver it to the shop.

- Aside from the obvious oil leak and keeping the levels topped up, if it's not leaking badly is there any downside to just riding as is, assuming it's not spewing oil heavily?

My CX leaked for sometime and I waited to do it myself. Unfortunately, it did a major dump on a long ride and I had to limp it back to the garage with stressful multiple stops to refill the engine. Best to do it sooner than later.

[twhitaker]

Keeping it 'topped up' might be THE problem. My bike pukes until the level gets mid dipstick then pretty much stops.

[Groover]

Is the rear main seal you mention the one where the drive shaft comes out?

If that's the one, then not too difficult as it can be replaced without digging into the engine, so that's the +. However, the rear swing arm assembly does need to come off, and that's not too difficult but some things will need to come out (wheel, lower shocks, brake caliper assembly, and I think that's it).

Parts to replace would be the "main seal", likely the dust cover that covers the main shaft joint, and probably a good time to inspect the swing arm grease seals, bearings, and also the main shaft bearing while that's all off.

[Groover]

Ok, maybe I have the main seal wrong. If it's the one the other have posted, then may be best to take it to a shop.

[bmc5733946]

There is also an engine breather pipe inside the clutch housing that is attached to the back of the crankcase that can be the cause of the oil leakage.  Does it only leak while running?  Does it leave spots after running?  Does it leak immediately after start up?  All questions that should be answered before blaming the rear crankshaft seal.  Could the breather hose be leaking at the point where it meets the pipe coming out of the top of the crankcase?  In all these cases careful assessment can prevent unnecessary work.

Brian

[Chuck in Indiana]

One thing that I didn't see mentioned is the hose to the breather pipe can be cracked. If so, breather oil will migrate into the bell housing and look like a main seal leak.
At any rate, find it and fix it. If it *is* a rear main, you just might end up like Black Cat did.. hoping you get home *and* an oily rear tire. 

Oh, I see that Brian typed faster than I did.. 

[Antietam Classic Cycle]

These about cover it all:

http://www.thisoldtractor.com/moto_guzzi_loopframe_engine_oil_leaks_from_the_bell_housing.html

http://www.thisoldtractor.com/moto_guzzi_loopframe_engine_out__check_these_things.html
(ignore the "Top of the engine" section)

[wymple]

I have a small leak at the rear main that I need to deal with. The only real problem, other than keeping a good eye on the oil level, is that the oil gets tossed around by the turbulence of the pressure plate/clutch/flywheel assembly, and the clutch gets oily and starts to slip. I spent the last riding season flushing it down in there with carb cleaner, about every 4-500 miles. I pulled the rubber plug on the side of the Cal II and sprayed it down while cranking the engine over a little, and let it run out the bottom. Stuff is cheap at Wal-Fart, 1.97, and one can was good for two washings. This year I actually fix it.

[GuzziChris]

Thank you everyone! This is a great forum, and I appreciate your expertise... 

[Tom]

This tip is from the old tips books put out by MGNOC.  Remember that this is temporary to get you through the rest of the riding season till the Winter when you can R&R the seal.  Add engine seal conditioner to the oil.  I used this on one bike.