The International CBX Owners Association

Hiya

My alternator will weep a few drops of oil for ever 100 miles or so. Is this normal or something I should bother to attend to? Cheers
Aris

Aris:

If the oil is seeping from the drain hole in the 'dry' side, then it needs attention. A sign that the seal is bad between the halves. I'd carefully check the clutch and bearing condition also - any debris coming from either could cause the seal to fail.

Dave

Hi Dave
As I understand it, yes it does come from what I think you mean by 'dry side', see pic below (from a previous dismantle of the alternator). The only way I can imagine oil seeping there is either through a failed alternator rotor bearing seal, or a less than perfect rotor bearing to rotor axle sealing ... ???

How can this have anything to do with the clutch ??

Thanks a lot, Aris

Aris:

I'm refering to the alternator clutch. Shards can come off of it and destroy the seal.

Dave

Hi Dave

On the money as usual, sorry I misunderstood you ...

So, seems I have a slow leak of engine oil, probably as a result of a failed rotor seal (part inside nylon bag in pic below). Why this has failed, I only recently had it rebuilt, I will investigate when I find time to open the alternator.Shards? I hope not!

Thanks and regards, Aris

Aris, you just might get lucky. I had an, identical, weep after my build. I disassembled the alternator assembly and noted that the rotor cavity was still dry. Turned out to be a, poorly sealing, 'O' ring between the alternator and the main case. I had used an aftermarket gasket kit and suppose the dimensions were off slightly on this item. It got cleaned and put back on with a, thin, smear of Toyota seal packing ( black). Problem solved.
You've paid your,hardship, dues buddy....hope you get the break you deserve.

Hmmmm. Possibly so.

In any case it is ever so minor, just enough to leave a drop of oil, or two, on my LH exhaust shield. And this, after a 240Km sprint (a regularity rally) last Sunday.
So I am not overly worried. How could I, after all I have been through.
The important thing is my motor (and entire bike!) now feel, sound and perform very well and I can't wait to open it up as I am about to finish running in
But guys, and I hope I am not the only masochist in the ICOA: I do - I really do - get a buzz when coming across problems, researching them, attacking them and eventually (hopefully) solving them. It is with anticipation and a sense of adventure that I will dismantle my alternator later in the weekend, and methodically try to identify the problem and find a solution.

All right, all right, I will now quietly go back to my cell, in the Athens psychopathic ward ...

Best, Aris

Ok, the weekend is here, I have taken leave from the ward and have decided to get to the bottom of this. I could ignore the problem for now as the bike seems perfectly rideable but what the hell, I might as well get to the bottom of this now. The rest of the bike is just so oil tight.

Perhaps more important, last time I removed the alternator, I noticed some ‘black rubbery soot’, sitting at the bottom of the engine (wet) side of the alternator, which frankly should not be there. Could this have anything to do with the weep?

Removing the alternator as a unit was as easy as undoing three 8mm bolts.

Sure enough the ‘black rubbery soot’ was there again but very little of it, if any.

The alternator itself was then split as carefully as possible not to erase any evidence of oil seeping through it. Sure enough, I could verify - no question about it – some oil, very little of it, was making it past the ball bearing. Some of it was escaping out of the drain hole as already observed, while some of it, was mixing with soot (carbon from the rotor brushes?) to end as a very light black oily smear, spread just about everywhere in there. Not good …

So how was oil passing through from the wet to the dry side?

Once I managed to undo the nut holding the alternator side clutch, and have the clutch plate lifted, the answer became obvious. The fat and elaborate oil seal designed to keep wet and dry separate, was sitting ~1.5mm proud of its intended ‘nest’. It was thus not only not doing its job properly, but had also self destructed by rubbing against the alternator side clutch plate.

Eureka! This 100% explained the black rubbery soot and how oil could make it to the dry side of the alternator.

In fact one could see clearly rubber from the seal sort of ingrained on the periphery of the neck of the clutch plate, on its way to becoming disintegrated and falling below as the infamous black rubbery soot!!!

To prove my point beyond any doubt, I took a socket of the correct size and tapped the damaged seal. Unsurprisingly it moved in by about 1.5mm to seat flush in its intended ‘nest’. This is where I lose my CBX for 10 days (my Commando's laughing at the other corner of the garage), and David Silver (bless him) makes his money ☺

As a side, a careful inspection of the clutch plates confirmed they are in perfect condition and wonder if they ever slip.

Well it seems like that clutch plate was unintentionally shimmed by the extruded seal, no? That would certainly reduce the potential for slip. Excellent job on the sleuthing as usual Aris, and thanks for sharing.

N.

Thanks Nils!
Yes, although I think this should increase the potential for slipping as the oil seal is stationary?
Best, Aris

Aris:
Should be no need to wait on David Silver. That is a very common seal available everywhere in the states. Should be available locally to you as well. Keep the Silver one when you get as a spare. Great explanation and photos.

Dave

Aris, you can use a drop of medium Loctite thread locker on the bearing under that seal so it doesn't move again.

Thanks Dave!
Ah the States, where seals walk in the streets.
Sorry mate but this is a looong way from our own United States of Greece ;).
Of course I will check and thanks all the same.

Jeff, you say the seal was actually pushed out? Doubt it myself.
I am inclined to think I did not push it home enough in the first place. No?

Cheers guys

Aris

Hi Aris,

I would still put a bit of loctite on the outer edge of the seal to make sure it does not move, after it has been fitted.

Cheers
Chris J.

Hi all

The new seal and o-ring arrived from the UK some time ago.
Had them replaced, and this time I did use a few drops of Loktite before driving the offending seal home. Then everything was put back together easy - peasy. This morning the weather took a change for the better, so took my Z out to test all this work.
Happy to report the problem is gone, and the bottom of my alternator assembly (together with the rest of the bike) is bone dry!

Thanks for all the suggestions chaps!
Aris