'85 LeMans Oil Leak inside the bellhousing

[mgmark]

Hello guys,
I stripped my bike to the frame yesterday to do a final build on it. I've ridden it a bit in the past year and it leaves a small oil drip under the center stand area. I split the engine and trans and found the inside of the bellhousing area to be fairly well coated with oil. The front of the trans is relatively clean leading me to believe it is the rear main seal. I've read up a lot of previous posts in the archives and it seems the best way to go is to do it all at once: replace the flange gasket, breather tube gasket, thread sealant on the lower flange through bolts, and JB weld the cam plug.
My question is: is it better to change the seal with the flange off the motor or in place? Also, when I pulled the flywheel there were no folded tab washers under the flywheel bolts. Should there have been?
What makes a good clutch alighment tool? A good used clutch input hub?
I am working with the motor by itself on my work bench.
Thanks

Mark

[Antietam Classic Cycle]

I prefer to pull the rear main bearing, replace the seal and reinstall with a new gasket (with a light coating of Permatex 300). Hondabond 4 seals the lower two bolts very well. I coat the two crush washers on the oil return pipe's crush washers with it as well. 

Hopefully there were "schnoor" washers under the heads of the flywheel bolts? That's what I use instead of the lockplates, along with blue Loctite on the bolt threads.

A used clutch hub makes a great alignment/compressor tool as long as you have a bushing, bolt and washer to go with it. If you need dimensions for the spacer and bolt, I can supply them.

[pete mcgee]

Also check the breather hose attachment where it bolts onto the rear of the engine case.
I had a similar mess when I was replacing the clutch and thought it was the rear main, it wasn't it was the breather leaking and the fly wheel did an excellent job if spraying it around.
If it is the rear main the post above is good advice.

[Antietam Classic Cycle]

Mark mentioned "breather tube gasket" in his original post. Yes, definitely replace that as well. I use a light application of Permatex 300 there as well.

Re: bolt and spacer to use an old clutch hub as an alignment tool:

The bolt is M12-1.5 x 90. The spacer is machined to be a snug fit into the old hub like so.

[mgmark]

Thanks for all the replies, guys. I'm going to replace everything while I'm in there. I found I have a new oem Guzzi rear main seal in the box O spares when I bought the bike. Is there any way to know if it is a Viton seal or not?

And thanks for the info on that spacer Charlie. I'll be making one up.

[pete roper]

If it is brown it will almost certainly be a viton seal, especially if it is directional. If it is blue it's one of the earlier fluorocarbon type seals. If it's black it wil be a standard nitrile seal.

I would suggest if it isn't a directional viton seal you buy one.

Pete

[mgmark]

If it is brown it will almost certainly be a viton seal, especially if it is directional. If it is blue it's one of the earlier fluorocarbon type seals. If it's black it wil be a standard nitrile seal.

I would suggest if it isn't a directional viton seal you buy one.

Pete

Thanks Pete,
It is black so it looks like I will be adding to my part order. 

[Idontwantapickle]

I might add that you should replace the fly wheel bolts with new ones.

 :1:

[rodekyll]

Don't forget to reinstall the flywheel with the timing points where you want them.

[canuck750]

While you have the flywheel off replace the two crush washers sealing the vent tube bolt that passes through the engine crank case and dips into the oil pan reservoir.

I just finished replacing these two crush washers on my Eldorado after an initial rebuild and then a second replacement of the rear seal.

This time when I stripped the flywheel off I left the engine in the frame tipped don to the rear and with a full crankcase of oil I watched the leak pattern for a couple days. Sure enough it was the crush washers, tow new washers, torque down the bolt and no more slow drips.

[Antietam Classic Cycle]

While you have the flywheel off replace the two crush washers sealing the vent tube bolt that passes through the engine crank case and dips into the oil pan reservoir.

I just finished replacing these two crush washers on my Eldorado after an initial rebuild and then a second replacement of the rear seal.

This time when I stripped the flywheel off I left the engine in the frame tipped don to the rear and with a full crankcase of oil I watched the leak pattern for a couple days. Sure enough it was the crush washers, tow new washers, torque down the bolt and no more slow drips.

You'll notice in my first post, that I also apply Hondabond 4 to those crush washers. "Belt and suspenders" maybe, but it makes sure there's no leak.

[mgmark]

Update:  I have the rear main flange removed, the seal out, and the upper breather tube removed. The seal was the brown type, suggesting it has been changed at some point, but when I pulled the flange I noticed the spring inside the seal was not in place where it should be, partially out of the seal, maybe from pulling the flange but I don't see how. The main bearing gasket was in one piece, as well as the breather tube gasket. I just finished up JB welding the cam plug, and placed a parts order including flywheel bolts, schnoor washers, and gaskets.

A question:  Jim mentioned the crush washers for the oil return tube where it goes into the sump. My bike being an '85 no longer has this feature, but instead breathes into the main frame tube over the engine. I have found mayonnaise in there in the past. The machining was still done in the engine case for the earlier type breather return line into the sump, using a bolt plug in the hole. As I am building a '70s styled bike is there any advantage or disadvantage to using the earlier type breather can? I can add the metal oil return line inside the bellhousing easily enough, and I do have a new breather "in stock". I am not running a stock airbox.

Thanks for all the replies and great advice.
Mark

[canuck750]

You'll notice in my first post, that I also apply Hondabond 4 to those crush washers. "Belt and suspenders" maybe, but it makes sure there's no leak.

I went for suspenders, belts, clamps et all..... I lathered the torqued down bolt with a dollop of JB Weld and feathered it all around sealing the whole contraption to the block, damned if I am going to pull the transmission a 3rd time!

[Michael D]

Re: bolt and spacer to use an old clutch hub as an alignment tool:

The bolt is M12-1.5 x 90. The spacer is machined to be a snug fit into the old hub like so.

If I may add to Charlie's spot on information

New clutch plates for the EV back in early 2010, I crudely made an aluminum washer as a spacer and the transmission stabbed right in.  Last year's V7 Sport was in desperate need a new 4mm clutch to replace the badly stepped original 2mm hub, so I didn't think twice on using the old fabricated washer for a quick mating of the engine and tranny.  No such luck. I must of tried a half dozen times with all sort of new words spilling from my mouth.  Before heading to a machine shop, I gave one last attempt at a solution on the net and I scored.  Some one posted (can't remember who or where) that the aluminum spacers used for the center stand fits right into the clutch hub.  Gave it a try and yes, it fits like a custom made silk glove.   

[mgmark]

If I may add to Charlie's spot on information
 Some one posted (can't remember who or where) that the aluminum spacers used for the center stand fits right into the clutch hub.  Gave it a try and yes, it fits like a custom made silk glove.

Excellent!

[jacksonracingcomau]

Update:  I have the rear main flange removed, the seal out, and the upper breather tube removed. The seal was the brown type, suggesting it has been changed at some point, but when I pulled the flange I noticed the spring inside the seal was not in place where it should be, partially out of the seal, maybe from pulling the flange but I don't see how. The main bearing gasket was in one piece, as well as the breather tube gasket. I just finished up JB welding the cam plug, and placed a parts order including flywheel bolts, schnoor washers, and gaskets.

A question:  Jim mentioned the crush washers for the oil return tube where it goes into the sump. My bike being an '85 no longer has this feature, but instead breathes into the main frame tube over the engine. I have found mayonnaise in there in the past. The machining was still done in the engine case for the earlier type breather return line into the sump, using a bolt plug in the hole. As I am building a '70s styled bike is there any advantage or disadvantage to using the earlier type breather can? I can add the metal oil return line inside the bellhousing easily enough, and I do have a new breather "in stock". I am not running a stock airbox.

Thanks for all the replies and great advice.
Mark

Bit late
But I did exactly that to my 95 Cali engine, I had to drill & tap the hole, fitted early drain tube, banjo bolt & breather box (early no rocker vents)
Totally recommend it, nowhere for mayo to form, no oil in catch tank, uses none
One of Carcano's perfect designs that got modified badly over the years, was right in 1967