ST1100 Oil Leak

swilliams1005

swilliams1005

Police Technology Specialist
Joined
Feb 17, 2007
Messages
92
Age
48
Location
Winterville, NC
Bike
ST1300
Has ever had a oil leak near the wimpy 28 amp alternator:( i was looking under mine and since its been sitting the garage for a couple of days for coolant repair again:( i noticed that there was alot of oil build up around the alternator and was really wet on the bottom which dripped on the "y" on the exhaust. Is this a sign that i might have to take this alternator out to place a seal or something?
 
Sounds like the o-ring on the alternator. Not unheard of. As long as yur in there, why not upgrade to 40 amp. :D
 
Is it a gusher? How much do you use per change?

I just did the alternator. If it isn't leaking hard, I'd let it be. It's a very doable thing, but not a casual repair:) Gets to looking pretty lonely behind the motor with no swingarm...

EDIT:
You know what? That's just an O ring on the alternator, with 4 bolts holding it. A guy might be able to wiggle the alternator out far enough to change the O ring with out taking the whole thing apart. What do you think, George or John or somebody?
 
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By far the most common place for oil to leak from the 28A alternator is the spot where the wire harness emerges from the stator casing/cover. The stator windings are oil cooled in that design.

There's just a glob of epoxy (or similar resinous material) sealing that spot and on many bikes this eventually starts to leak. On my '93 the oil would leak inside the harness cover, travel up to where the 3P connector is and then drip from there making everything below and behind that spot oily and dirty. Replacing the 28A oil-cooled stator with the 40A air cooled alternator eliminates that epoxy seal and the leak with it.

There's no effective way to repair this leak so the choices are to live with it or do as George says.
 
I've only looked at pictures of the 1100 alt swap, so I certainly may be wrong here....

Although I don't think you can remove the o-ring without completely pulling the alternator, you might be able to do a temp repair with some RTV.

You would have to stretch the o-ring OVER the alt mounting tabs (from the back) since the 28amp unit is attached to the drive gear. Really not do-able.
 
Its not leaving a spot on the floor or anything just enough got on the outerside of the alternator that when the bike got good and warm(cooling fans kicked in) is when it dripped on the exhaust. Im going to keep a eye on it to watch the progress, Im going to clean it good to see if i can see where it is coming from before i do the swap:) wish i had the cash right now!!!
 
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I have Gunk engine cleaner on the bottom side of STick's motor _right now_ to clean things up. Trying to trace a leak, doesn't look like the alternator, definitely not the oil filter. _Might_ be around the shift linkage.

I'll post more later.

<edit> Looks like mine is leaking at the bottom/right of the 40 amp alternator. Must'a pinched the o-ring at assembly. <heavy sigh>
 
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I'm thinking Keith is probably right. I just thought if you could worry it out a couple of inches...probably not happening. The swap parts cost me just a touch over $500 from Service Honda. Included everything. Honda Fuse and box, and 2 sets of rear wheel o rings, for the next rear tire change.

I'm not the most recent changer, but darn close to it....

Good luck. And George, I'm watching your leak closely, too. So far, I am clean and dry in the alternator area.
 
BigTom said:
I'm thinking Keith is probably right. I just thought if you could worry it out a couple of inches...probably not happening. The swap parts cost me just a touch over $500 from Service Honda. Included everything. Honda Fuse and box, and 2 sets of rear wheel o rings, for the next rear tire change.

I'm not the most recent changer, but darn close to it....

Good luck. And George, I'm watching your leak closely, too. So far, I am clean and dry in the alternator area.
Click to expand...

Could you send me a list of all the parts you bought for the swap on your bike including the part numbers. Thanks
 
I thought I had the dreaded alternator leak on my 2000 ST1100 when I switched to synthetic oil. It started putting a sizeable puddle on the floor at idle as soon as I had my back turned. I cleaned and washed the area down and found that I was able to stop the leak by tightening the corner bolt that runs vertically into the crankcase, right above the left side of the alternator.
When I had the socket on it and applied torque I heard it make a loud "snap" as it turned, and thought I must have broken the 6mm bolt, but it just snugged it up and it hasn't leaked a drop since.
 
Hi Stephan, and All,

Three sources of 28amp alt related oil leaks:
- the O-ring* on the alt shaft assy (seals it to the engine case)
- the O-ring on the stator (seals it to the alt shaft assy)
- where the wire harness enters the stator

* this is the one I have anecdotal data on a number of failures. R&R requires swingarm removal and use of a Lewis-Pin.

George, just a thought but your leak might be the Pulse Generator gasket like the seep on my SSMST that I just poSTed about (with pic) over on ST-Riders...(?):
http://www.stocrallies.com/st-riders/index.php?topic=1480.0
Edit 27 Nov ‘21: http://www.st-riders.net/index.php?topic=1480.0

40amp Alternator Upgrade info and parts lists... everything you need to know... start here in the ST1100 Archive Of Wisdom (including Don da Roza's cool new 'alt insertion method' videos!!!):
http://www.stocrallies.com/st-riders/index.php?topic=942.0
Edit 27 Nov ‘21: http://www.st-riders.net/index.php?topic=942.0

[or go here direct for just the tools and parts lists: http://home.insightbb.com/~mmartin36/JohnO_list.htm]
Edit 27 Nov ‘21: http://koczarski.com/mmartin/JohnO_list.htm

Stephen, if the cost of new alt upgrade parts is prohibitive right now, keep your eye out for a salvage unit and all its necessary parts (except for the one new O-ring you'll need). You really should spring for a Service Manual if you haven't already.

HTH

BTW, just got another report of a high mileage 28amper failing and stranding an STrider on the side of the road. He had no warning because he wasn't running a voltmeter. There's a lesson there...

Regards, John
 
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Thanks for the great info John. I have my Eye on a 40amp on eby right now. I do have a service manual that ive been reading front to back. Good thing is i do have a voltmeter and always keep my eye on that thing just in case.
 
Thanks, John, I'll check the pulse generator gasket.

There's a 40 amp alternator without the base on E-Bay right now. Current bid is just over a $100. Might be worth a look.
 
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Mine looks like the oil might be leaking out the bottom allen head bolt on the generator assm. Tried snugging with no success. Do you think I might have success pulling that bolt and cleaning the threads out with some carb cleaner and air then reinstall the bolt with some silicone gasket maker?
 
liverup said:
Mine looks like the oil might be leaking out the bottom allen head bolt on the generator assm. Tried snugging with no success. Do you think I might have success pulling that bolt and cleaning the threads out with some carb cleaner and air then reinstall the bolt with some silicone gasket maker?
Click to expand...

The leak won't be from that bolt. That is just the lowest point the oil travels to. You have the common leaky oil seal at the alternator itself, or, you have an oil leak from the wiring harness that enters at the rear of the alternator.
 
Bush said:
The leak won't be from that bolt. That is just the lowest point the oil travels to. You have the common leaky oil seal at the alternator itself, or, you have an oil leak from the wiring harness that enters at the rear of the alternator.
Click to expand...

Its not the harness.
Looks like there are 2 o rings. My leak must be coming from the most outer The piece held on with the allen head bolts. Looks like I could pull that part of the generator off w/o removing swing arm. Is that a possibility does anyone know?
 
just looked in my manual. It's the stator oring leaking. I am wondering if the stator can be removed w/o pulling swingarm?
 
liverup said:
just looked in my manual. It's the stator oring leaking. I am wondering if the stator can be removed w/o pulling swingarm?
Click to expand...

Mine is doing the same thing. Unfortunately I'm pretty sure we are looking at pulling the swingarm. Because of that, when and if I get around to doing this, I do have the 40 amp stuff to put back in.
 
liverup said:
just looked in my manual. It's the stator oring leaking. I am wondering if the stator can be removed w/o pulling swingarm?
Click to expand...

Swingarm has to come off. Be aware that those allen bolts are in there very tightly and not very thick in diameter and can shear off relatively easily. Two of the three sheared so easily when I pulled the stator on my previous '95 model. That opens the can of worms to a whole lot of other problems. Best to give them a sharp rap with a drift before trying to remove them, something I didn't do.
 
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