First let me say that I'm usually pretty good at troubleshooting, especially mechanical issues, but I've got something going on that I haven't been able to explain yet. The transmission oil on my 2011 Limited is vanishing without a trace.

Here's some background...

I don't usually make a habit of checking the trans oil very often because short of a visible leak, where is it going to go? Right? That's been my thought.

Nevertheless, a couple weeks ago I checked the level and found it a little low. I added 8 ozs. This was about 3,500 miles since I changed the oil and although I knew in my mind that when I changed the oil it was at the correct level I thought it's possible that I could have made an error and not filled it completely.

One week and 400 miles later I checked the oil level again and found it low again. This time I added 4 ozs.

Three days and about 225 miles later, today, I checked the oil level and again it is lower than when I added the oil three days ago. I didn't add any oil this time as I'm going to ride it and keep monitoring it for a few more miles.

So... Where is the oil going? I'm not intimately familiar with the interfaces between the trans, eng, and primary and any potential internal leakage between the units so I can only speculate at this point.

My first thought was that there maybe a trans seal leaking that would allow the oil into the primary. I'm not sure if that's possible but I checked the primary for an overfull condition nevertheless. I drained and measured the primary oil and what I removed was 36 oz. This is very close to the 38 ozs. I put in at the last change so I've eliminated that possibility. EDIT: Continued monitoring indicates trans oil is getting into the primary. See my posts from #19 and on.

The only other place the oil can go is into the engine. Possibly a leak between the chambers of the oil pan. Right? But I haven't been able detect a change in engine oil level yet, although I will start to keep a really close eye on it.

Right now I'm just looking for ideas any of you guys might have that I haven't thought of.

Additionally, any description of the oil pan chambers and how the engine and trans oil could possibly mix from that perspective.

Anyone?

 

I googled your problem and below is what I found. It is from another forum where a person had the EXACT same problem that you are having. You stated that you have added 12 oz over time. You also said that it might be possible that the levels were not correct after your oil changes. Maybe the primary was low before you added fluid to the trans and what leaked out topped off the primary. I am not trying to be smart or anything, you asked for help and no one has responded all day, so I am trying to help. Anyway, the forum is HD talking. In the thread the there is talk of a hollow main shaft that can leak from the trans to the primary and a seal to. Dont flame me everyone for the post about another forum, lol, just tryin to help. Here is the link below, I really hope you find your problem and get it fixed, it would bother the hell out of me if I were in your shoes. By the way, do you have ESP? If you dont find anything out, I would let them try to figure it out, thats what the warranty is for. Good luck man.

 

It cannot go into the engine unless there is a leak across the oil pan ? The trans and engine share a divided oil pan? Could it be going out vent? Usually even a tiny leak is visible though?

 

Time to pick up some UV dye and a black light. That would make it pretty easy to diagnose. Pick some up at Napa.

 

The problem is the Clutch push-rod & tube runs between them and although there is a seal, some oil tends to run into the Primary cover. This is why I run the same oil in both. It's a known problem.

 

This is a weird one. You would think if there WAS a leak between the trans or primary, your level would be low on one and high on the other. Do you check the trans level the same way every time? I know the level can be hard to read on the dipstick. If there was a leak or even it was coming out of the vent it would be visible. A seal leak would be visible as would a drain plug leak. I had a clutch cable leak under the cam housing on my old Evo, but that leak was obvious. The dye trick like mentioned is probably gonna be your best bet at this point. By the way, what oil are you using in the trans? Gear oil would smell different the motor oil, even if it was mixed. Some guys use that pink stuff that would make it easy to tell if it was leaking.,,

 

If it was a leak in the engine/trans pan I would think it would be going the other way. Your trans would be filling up. 4qt vs 1qt

Put a plastic bag over the vent hose with a rubber band. Go for a ride, then check the bag and see if there's any oil. If there's oil in the bag, then you have to figure out why your transmission blows.

 

First off, thanks to all who have replied. I guess my plan is to continue to monitor this issue. I’ll be due for an oil change in another 1500 miles or so and if I haven’t isolated the problem by then I’ll go ahead and change all of the oils and precisely measure how much oil goes into each hole. Then I’ll ride the bike for 1,000 miles or so and drain and measure what comes out of each. That’s what I’m thinking now anyways.

I read the link you provided. One idea I got from reading that thread was related to the vent tube. I’m going to check my vent to make sure I don’t have any obstruction there. My rational is that if the vent has an obstruction, pressure could build in the trans and force the oil somewhere… But where is still my main question since I have no external leakage.

As for the oil levels, I mentioned that in my OP simply because I knew someone would ask “are you sure it was filled properly to begin with?” and while unlikely but not impossible, I could have made a filling error at the last oil change. I really don’t think that’s the case as I’m pretty meticulous. Additionally, I drained the primary and measured the amount drained and it was consistent with the 38 ozs. I put in at the last change. EDIT: Further monitoring of the oil levels indicates trans oil is making its way to the primary. See my posts #19 and on.

And finally, as far as taking it into a shop… That is not happening. Just not in my nature.

I’ve considered the leak between the chambers of the oil pan and asked for guidance with that specific possibility in my OP.

The oil is not going out the vent. Like I said there are no external leaks. I am going to check the vent for an obstruction though as I mentioned above.

I’ll consider this… But I have to wonder if it will be helpful. If there trans oil is finding it’s way into either the primary or engine oils, once it mixes with the higher volume of either, would the dye be detectable?

Although this could be a real and legitimate possibility, if it were the case, I should see an increase in the oil level of the primary. I haven’t seen that. EDIT: Further monitoring of the oil levels indicates trans oil is making its way to the primary. Furthermore, you are correct that the oil is making its way through the clutch push rod passage, but incorrect that there is a seal. There is no seal. See my posts #19 and on.

Yes, I’m very careful to check the oil levels the same way everytime. Same positioning of the bike, same temperatures, etc.

I’m running Mobil 1 75W-140 in the trans and have tried to smell the other oils to determine the presence of gear lube, but that has been inconclusive to this point.


I’m not sure which way the oils would go if there was a leak between chambers in the oil pan. I just don’t know the configuration of the pan well enough to make that determination.

As for the vent, I’m certain it isn’t blowing anything out there.

 

You would think with 4 qts in the engine side and 1 qt in the trans, the 4 qts would win gravity wise, and the trans would fill up with engine oil.

 

With the dye at least you could confirm where the oil is going.