Dreaded 28 amp alt oil leak

I believe I have the dreaded 28 amp alternator oil leak and it may be coming from the o ring. I have included a picture of the leak in case anybody has any other ideas as to the source of the leak. My bike is a 1994 abs and has roughly 81,000 miles on it. The only aftermarket electrical loads I put on the system are a gps, led brake light and one heated vest which uses about 3.6 amps. I have no plans for any other electrical loads.

At the moment I don?t have a good place to work on my bike so I won?t be attempting a fix for now and I?m not sure that I would want to anyways. But in case I do I have some questions:

1.Do these leaks ever become catastrophic? Can I just run the bike the way it is? I don?t think I?ve ever owned a vehicle that didn?t have at least one spot that weeped a little oil.

2.Is it easier to just replace the 28 amp alt with another 28 amp alt instead of doing the upgrade even though the swing arm etc. still has to come off? I have no plans on ever increasing my aftermarket electrical requirements (famous last words?).

3.How difficult is the job? When I was younger I use to do my own brake jobs, water pumps etc. but never truly enjoyed it or was particularly good at it.

Forget about all of the attached thumbnails. I was going around in circles trying to get the picture, "right side up"!

As mentioned in another thread, similar issue:

there two O-rings, one seals the drive case towards the engine block, the other seals the stator case against the drive case... give the area a good rinse with brake cleaner to determine which one has failed.
Wanna be sure, do both though...
Also keep an eye open if the leak is not caused by the resin/epoxy seal on the wiring exit of the stator...

The failure is basically just annoying and messy; besides of "marking its spot", a brief but significant stench might arise while idling at a red light, cause an oil drop is landing on the LHS downpipe.
I've yet not heard nor seen a case where those O-rings just went "boom" and released the entire engine oil at once...

Difficoult? Depends...
Doing it with your belly on the garage-floor is "ooch!"... ;-)
A lift/worktable is very helpful... (one of the reasons I got me one...)
Panniers, seat, side panels off, license-plate holder off, rear wheel out, tank out (see to aim for a low fuel level when scheduling the surgery), drain and detach plumbing of rear brake, remove swing-arm... now you can access the alternator...

I swapped a stator case + new O-ring in ~4 hours total when refurbing the '94... all tools provided, also the socket for the swing-arm locknut, and on the motorcycle worktable which is very convenient for this job...

It ain't rocket-science, but the thing sits pretty deep inside the motorcycle... and while that far in, you'll surely find a bunch of other issues to take care off...

ST1100Y said:

As mentioned in another thread, similar issue:

there two O-rings, one seals the drive case towards the engine block, the other seals the stator case against the drive case... give the area a good rinse with brake cleaner to determine which one has failed.
Wanna be sure, do both though...
Also keep an eye open if the leak is not caused by the resin/epoxy seal on the wiring exit of the stator...

The failure is basically just annoying and messy; besides of "marking its spot", a brief but significant stench might arise while idling at a red light, cause an oil drop is landing on the LHS downpipe.
I've yet not heard nor seen a case where those O-rings just went "boom" and released the entire engine oil at once...

Difficoult? Depends...
Doing it with your belly on the garage-floor is "ooch!"... ;-)
A lift/worktable is very helpful... (one of the reasons I got me one...)
Panniers, seat, side panels off, license-plate holder off, rear wheel out, tank out (see to aim for a low fuel level when scheduling the surgery), drain and detach plumbing of rear brake, remove swing-arm... now you can access the alternator...

I swapped a stator case + new O-ring in ~4 hours total when refurbing the '94... all tools provided, also the socket for the swing-arm locknut, and on the motorcycle worktable which is very convenient for this job...

It ain't rocket-science, but the thing sits pretty deep inside the motorcycle... and while that far in, you'll surely find a bunch of other issues to take care off...

Click to expand...

Thanks for the reply. When I get a chance I?ll clean things up as you stated and have a closer look. Also, like you said there may be some other issues to take care of. In another year I?ll be due for a timing belt according to the factory recommendation. If I can avoid any major work until then I could give the bike a real good going over at that point in time. Alternator upgrade, head set bearings, timing belt, water pump and all coolant hoses etc. at the same time. This also gives me year to decide on whether or not to do it myself. I would have to get myself set up with a better place to work on the bike and at this point I find the whole thing a little overwhelming. Maybe I just need to look at it as a bunch of individual projects and not as a whole.

I was talking to one of our local independent motorcycle shops this morning about my alternator issue. It didn?t sound like he was familiar with the alternator upgrade but was receptive to the idea of doing it if I ordered the parts. It was refreshing being in a shop where they didn?t automatically criticize forums and anything that wasn?t factory recommended.

I?ve done a lot more reading on this issue since I first started the thread. There sure is a ton of very good information out there. I really appreciate the time and effort people put into these forums to communicate their experiences with these awesome machines.

FWTBT said:

I was talking to one of our local independent motorcycle shops this morning about my alternator issue. It didn’t sound like he was familiar with the alternator upgrade but was receptive to the idea of doing it if I ordered the parts.

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So much about customer service... ;-)
By this he's not the one getting grilled if an item is wrong or missing...

It was refreshing being in a shop where they didn’t automatically criticize forums and anything that wasn’t factory recommended.

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Well, to a part "the internet" is dangerous... lots of bogus, sometimes inadequate, yet even false info and a zillion scaremongering of course...
One really has to filter reliable, useful info from there...
But nor shared (correct) info is kinda wasted...

The plan to opt for a mayor overhaul, where you're doing just all in one hangar-session sounds very reasonable...
You can now unhurriedly order all the parts you will and might require, check if not a bolt, O-ring or gasket is missing, check for tools, etc...
Way better then getting stuck with a halfway parted motorcycle on the platform cause one small item is missing...

With a '94, your due a timing belt NOW. 20 year old belt. Couple of years ago I changed my '91's belt at 80K and it had some rough edges.

ST1100Y said:

So much about customer service... ;-)
By this he's not the one getting grilled if an item is wrong or missing...


Well, to a part "the internet" is dangerous... lots of bogus, sometimes inadequate, yet even false info and a zillion scaremongering of course...
One really has to filter reliable, useful info from there...
But nor shared (correct) info is kinda wasted...

The plan to opt for a mayor overhaul, where you're doing just all in one hangar-session sounds very reasonable...
You can now unhurriedly order all the parts you will and might require, check if not a bolt, O-ring or gasket is missing, check for tools, etc...
Way better then getting stuck with a halfway parted motorcycle on the platform cause one small item is missing...

Click to expand...

Good point about customer service and I agree that the internet can be dangerous but I think if one uses common sense, does lots of research and considers the source of information it can be very useful.

I cleaned things off this morning and had a better look. The alt is definitely leaking from the rear o ring. I pulled the plastic cover back from where the wires enter the alt and had a look. It may be leaking there as well but is hard to tell. It did feel a little moist/oily. I'm not sure what the factory sealant would look or feel like but the stuff that is there now is black and feels like silicone. It is soft and pliable. I have my suspicions that someone has been in there before in an attempt to slow a leak.

After tinkering with the bike this morning I am starting to consider doing the work myself. After spending a day on the back of my bike earlier this summer my wife has decided she wants her own bike. We could buy her bike this year and I could start working on my bike next year/winter. That way I would have something to ride while I'm working on mine. I think she might like a smaller dual sport.

BuddingGeezer said:

With a '94, your due a timing belt NOW. 20 year old belt. Couple of years ago I changed my '91's belt at 80K and it had some rough edges.

Click to expand...

Better to do it sooner than later I suppose. I don't have any lengthy trips planned for next summer like the past 2 summers so I am hoping I can get by one more year before I have to start to dig into the bike.

FWTBT said:

Better to do it sooner than later I suppose. I don't have any lengthy trips planned for next summer like the past 2 summers so I am hoping I can get by one more year before I have to start to dig into the bike.

Click to expand...

I had to change the rubber band on the black bike before it hit 80,000 as I had inspected it at 60,00 and it was fine, but while doing some other stuff, I had pulled the radiator and decided while in there to look again and there were several strings hanging from the block side of the belt. The belt on the Two Tone is now at 91,000 so it will be changed out soon (The bike likely being worked on this weekend but will be parked for the job at any rate)

I changed the alternator on the black as well, after thinking it was leaking, I managed to break off an ear from the block side mount, fixed it and then broke another off the case side trying to stop that leak that wasn't there (turned out to be a crack in the valve cover and it weeped into the spark plug recess that then has a weep hole on the back of the head right over the position for the alternator. Mine looked exactly as your does, but the leak was above it, and it wasn't until I was on the 4th or 5th alt. removal that I noticed it ... Of course after buying the new one. I bet the cracked one would still work, just looks ugly as sin.

oh god. do we have the same problem here?
my 1995 st1100 also has an oil leakage and has been to 2 workshop, none of them could fix the problem
they said that the leakage coming from the seal located behind of the alternator. and they told me that the seal can't be replacable as it is permanently attached with the alternator. So no seal is available everywhere. Also they said that inside the body of seal, there is an IC component so they are afraid to spoil the IC if try to replace with substitute seal.

does it make any sense? I like riding but I am not in to the engine so I don't really understand.

more of it, a lot of my seniors in big bike said that st1100 will have a lot of trouble, they are suggesting to sell it before all the trouble comes to me. is that true?

boy_christian said:

...they said that the leakage coming from the seal located behind of the alternator. and they told me that the seal can't be replacable as it is permanently attached with the alternator.

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Now that's funny... ;-)
A 26A alternator has 2 O-rings, the air-cooled 40A unit one O-ring.
On a 26A stator the wiring exit could start to leak though... but also there are options to fix that.
Its probably more the case that the ST1100 is quite rare and "exotic" in your area, thus no mech is really experienced/willing in working on that rig...

more of it, a lot of my seniors in big bike said that st1100 will have a lot of trouble, they are suggesting to sell it before all the trouble comes to me. is that true?

Click to expand...

Even more entertaining... :lol:
If the ST1100 sees some quality maintenance its pretty much bulletproof...
If the bike is neglected, some issues might arise sooner or later... due the genuine quality probably later though... ;-)

Roam the entries here to smarten yourself about the "what to check" items and procedures, and learn to perform the basic maintenance yourself...
A genuine workshop manual and some decent tools its all it takes.

boy_christian said:

oh god. do we have the same problem here?
my 1995 st1100 also has an oil leakage and has been to 2 workshop, none of them could fix the problem
they said that the leakage coming from the seal located behind of the alternator. and they told me that the seal can't be replacable as it is permanently attached with the alternator. So no seal is available everywhere. Also they said that inside the body of seal, there is an IC component so they are afraid to spoil the IC if try to replace with substitute seal.

does it make any sense? I like riding but I am not in to the engine so I don't really understand.

more of it, a lot of my seniors in big bike said that st1100 will have a lot of trouble, they are suggesting to sell it before all the trouble comes to me. is that true?

Click to expand...

Regardless of where your alternator oil leak is, if it IS the alternator, it should not get any worse and only provides you with a whiff of burning oil on occasions of start up and sitting in traffic. The wiring seal is not easily fixable, but a leaky O-ring is. As far as troubles with an older ST, they are nothing more than normal wear and tear maintenance issues. The ST1100 has a reputation of being "bullet proof", but does require certain things replaced and maintained as the mileage starts to mount. Having a dealer do some of those things CAN be expensive however, like a timing belt change, so anything you could learn to do yourself will save some BIG dollars. The ST1100 is also well known to be very easy to work on, even for those with limited skills, as long as you have some good tools and the Honda Service Manual.

I now see Martin has already stated most of what I said.

FWTBT said:

Good point about customer service and I agree that the internet can be dangerous but I think if one uses common sense, does lots of research and considers the source of information it can be very useful.

I cleaned things off this morning and had a better look. The alt is definitely leaking from the rear o ring. I pulled the plastic cover back from where the wires enter the alt and had a look. It may be leaking there as well but is hard to tell. It did feel a little moist/oily. I'm not sure what the factory sealant would look or feel like but the stuff that is there now is black and feels like silicone. It is soft and pliable. I have my suspicions that someone has been in there before in an attempt to slow a leak.

After tinkering with the bike this morning I am starting to consider doing the work myself.

Click to expand...

Where are you now on this project? I will be diving into there myself in the next few weeks, as my '95 alternator packed it in early this summer. It also has had an oil leak for a few years, from the wiring connection area. My solution, at the time of the alternator failure, was to buy a nice '96 that I found in Sechelt and ride it for the summer, but now I must get the other one repaired.

Since you are only dealing with an oil leak, at this time, you might want to ignore it and do your other work first, if just to get a little more comfortable with wrenching on the bike. Have you got the Honda Service Manual? BIG help right there. How is the alternator performing at this point? Is all the wiring and its connectors in good shape? Corroded and burnt connectors are usually what lead to the 28 amp alt failures.

My '95, owned since new, went almost 20 years and over 160,000 kms on the old 28 amper, but I also put very little extra demand on the system, with only 55/60W headlights and a heated vest. I'm thinking you might be well advised to replace the stator, if you intend to go in there anyway just for the oil leak issue.

Sit down before you ask your dealer to quote the stator price, but since you are likely sitting now, I'll tell you. Carter Honda in Vancouver quoted me $540.00! Needless to say, I went online and the best price I found was from Partzilla in Georgia USA at $302.00 US. Even with exchange and shipping, it is much cheaper and I also ordered a number of other parts and maintenance bits (brake pads, rubber cush dampers and inserts, etc) to make the extra savings with the same shipment. Ordering ST parts from the USA is definitely the only way to go. My last three part orders from the USA, not all from Partzilla, came to my door by Canada Post with no extra duty or customs charges attached. I expect my new stator and other stuff to arrive in a few days.

Bush said:

the best price I found was from Partzilla in Georgia USA at $302.00 US

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Are you installing a new alt? 28 or 40?

DeanR said:

Are you installing a new alt? 28 or 40?

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Since my original 28 amper went almost 20 trouble free years, I am replacing the stator only. I see no sense in going to the added aggravation that a 40 amp upgrade would entail.

Bush said:

I am replacing the stator only

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Would that be #9 on the fiche?
http://www.hondaparts-direct.com/fiche_section_detail.asp?section=2547684&category=Motorcycles&make=Honda&year=1994&fveh=132610

DeanR said:

Would that be #9 on the fiche?
http://www.hondaparts-direct.com/fiche_section_detail.asp?section=2547684&category=Motorcycles&make=Honda&year=1994&fveh=132610

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That would be it. Partzilla is cheaper.

ST1100Y said:

Now that's funny... ;-)
A 26A alternator has 2 O-rings, the air-cooled 40A unit one O-ring.
On a 26A stator the wiring exit could start to leak though... but also there are options to fix that.
Its probably more the case that the ST1100 is quite rare and "exotic" in your area, thus no mech is really experienced/willing in working on that rig...


Even more entertaining... :lol:
If the ST1100 sees some quality maintenance its pretty much bulletproof...
If the bike is neglected, some issues might arise sooner or later... due the genuine quality probably later though... ;-)

Roam the entries here to smarten yourself about the "what to check" items and procedures, and learn to perform the basic maintenance yourself...
A genuine workshop manual and some decent tools its all it takes.

Click to expand...

thanks so much for your respond to this. I guess I should dig more info to fix my problem here. I preety much still love this bike. does anyone knows where can I download that genuine workshop manual?

boy_christian said:

thanks so much for your respond to this. I guess I should dig more info to fix my problem here. I preety much still love this bike. does anyone knows where can I download that genuine workshop manual?

Click to expand...

Try ebay,no 281380541787

do we have to bring down the engine block to fix the seal on the alternator?