1974 850T Clean oil leaking from bellhousing

[sanderoudev]

Hi,

I just introduced myself in the introduction subforum.
My name is Sander and i'm from the Netherlands.
I own a 850T from 1974 which i'm currently rebuilding.
The engine and transmisssion i did not take apart, because the previous owner did rebuild them. (proof on paper)
The last year the engine didn't turn over but last week there was quite a puddle of clean oil underneath the bike.
It seems to be coming from the cutout between the engine and tranmission, the slot that is i guess for letting oil out when there is a leak.

Next week i'm going to split the engine and tranmission to inspect and replace all neccesary parts.
I'm going to crab the frame, but i have a couple of questions;
1. What tools do i need to remove the flywheel, clutch and seals/bearings.
2. While i'm in there, what parts should i replace as a precaution?
3. Are there any tips / tricks involved ?

Regards,
Sander

[paulbricey]

What does the oil smell/feel like ?? Gear oil, engine oil (usually not clear, but can be if it's not been run), or hydraulic fluid (unlikely but who knows where brake fluid could be leaking from & too ?).

[jhem68]

Start here for all the possible sources of an oil leak at the bell housing weep hole
https://www.thisoldtractor.com/moto_guzzi_loopframe_engine_oil_leaks_from_the_bell_housing.html#google_vignette

After the transmission and clutch are removed, I would recommend doing the fixes for all the possible sources of eigne oil leaks while it is apart even if you have thought you had a clear indication of the source. You wouldn't want to find it still leaking after putting it back together. BTDT!

I know this link is referencing a loop frame, but the same applies to your 850T. Lot's of info on This Old Tractor site.


John H

[sanderoudev]

What does the oil smell/feel like ?? Gear oil, engine oil (usually not clear, but can be if it's not been run), or hydraulic fluid (unlikely but who knows where brake fluid could be leaking from & too ?).

It has no smell, or my smell is not to great. It feels like 'thick' oil so not likely to be brake fluid.
Engine has been run, and the dipstick also shows brown oil. Likely to be atf oil.

[guzzisteve]

If you enter what you want in the search box in upper RH corner of page you will get all sorts of answers, try a search.

[moto]

It has no smell, or my smell is not to great. It feels like 'thick' oil so not likely to be brake fluid.
Engine has been run, and the dipstick also shows brown oil. Likely to be atf oil.

850Ts don't use ATF. Sometimes ATF is introduced into the bell housing to free stuck clutch plates. I would check the levels of your different oils and ride it some more. Maybe the ATF flow will be exhausted.

[sanderoudev]

850Ts don't use ATF. Sometimes ATF is introduced into the bell housing to free stuck clutch plates. I would check the levels of your different oils and ride it some more. Maybe the ATF flow will be exhausted.

Sorry what i meant was gearbox oil.
Overnight it lets about 2/3 drops on the floor.
So driving it doesn't seem to be the wise thing to do.

[moto]

Sorry what i meant was gearbox oil.
Overnight it lets about 2/3 drops on the floor.
So driving it doesn't seem to be the wise thing to do.

Thanks, that makes more sense. Best to follow your plan, then.

[Antietam Classic Cycle]

Gearbox oil could be clutch pushrod seals. If whoever rebuilt it reused the original tight fitting hard plastic tube, then no wonder. If they used the "upgrade" rubber cones, I've had those leak as well. That's why I use the six o-ring stack now.

Unfortunately, the clutch is likely oil fouled now.

[moto-uno]

  ^ +1 For what Charlie said ! And don't forget the "O" rings under and at the inner edge of the splined input shaft ( the ones the clutch friction plates ride on ) .

[sanderoudev]

Gearbox oil could be clutch pushrod seals. If whoever rebuilt it reused the original tight fitting hard plastic tube, then no wonder. If they used the "upgrade" rubber cones, I've had those leak as well. That's why I use the six o-ring stack now.

Unfortunately, the clutch is likely oil fouled now.

I will look into this. No matter what the box should come of then.

  ^ +1 For what Charlie said ! And don't forget the "O" rings under and at the inner edge of the splined input shaft ( the ones the clutch friction plates ride on ) .

Thanks you, will check this aswell!

[TOMB]

Note
The two lowest bolts on the rear main  bearing are through bolts directly into the crankcase and may also leak due to lack of sealant or dried out sealant.

The rear main gasket is probably  dried out.

Also the vent pipes especially  the one o'clock position gasket dried out.

The large   vent pipe that goes to the breather box the hose clamps could be loose which would allow oil to drip outside  between the hose and large pipe into the bell housing as the pipes both of them float where they enter float and don't seal as they pass through.

TOMB

[John A]

This vid may help, besides what Tomb said, note the sealant on the cam plug
https://youtu.be/7PyvYjdPUr8?si=R-ZjMJ10kYLWYjW7

[sanderoudev]

Well after 2,5 hours the box is out.

It's leaking from the pushrod.
The plates are contaminated as well.
The starter gear looks rather nasty. Is it necessary to replace?

And the seal in the output side als leaks. Meaning there is oil inside the swingarm.
If I clean this up, it should be ok? Or should I replace the bearing in the swingarm now?

[jcctx]

If clutch friction plate not to worn brake cleaner will most likely make it work normally. Or, it might pay to replace while in there anyway????

[guzzisteve]

You will need to take off nut on output shaft & change seal. Get brown ones they seal better than blue ones.
There is a speedo metal ball in a slot after nut comes back, make sure you catch it w/magnet.
That starter ring gear looks OK to me.
If you take off the imput hub on trans you can use it to alien the plates on assembly. There is also a seal & orings there too.

[Moparnut72]

Replace the clutch disc, if it is oil contaminated there is no way to get it out. I had brake pucks that suffered from leaking fork oil. I cleaned with brake cleaner also, no go. I replaced them. I don't think you want to go through this a second time. A few bucks for a new disc is a lot cheaper than tearing it all apart a second time.
kk

[sanderoudev]

You will need to take off nut on output shaft & change seal. Get brown ones they seal better than blue ones.
There is a speedo metal ball in a slot after nut comes back, make sure you catch it w/magnet.
That starter ring gear looks OK to me.
If you take off the imput hub on trans you can use it to alien the plates on assembly. There is also a seal & orings there too.

Thank you, i will see if i can get some Viton seals here.

Replace the clutch disc, if it is oil contaminated there is no way to get it out. I had brake pucks that suffered from leaking fork oil. I cleaned with brake cleaner also, no go. I replaced them. I don't think you want to go through this a second time. A few bucks for a new disc is a lot cheaper than tearing it all apart a second time.
kk

Yes i will replace the disk. Don't want to be in here a second time.