MTX Leaks at track.

[Shoaz]

My 95 MTX track car has developed an interesting problem. It doesn't leak under normal use and doesn't spot my garage floor. However, at track events when I stop in the paddock it'll leave a significant puddle of transmission fluid. When it gets back home, it doesn't drip again.

It's been getting worse for a while, and a few weeks ago I replaced the right-side output shaft seal since it looked like that was where the fluid was coming from. During our last get-together at Dooleyville we put it on the lift and Jason (YamahaSHO) and I looked around for other culprits. The speedometer cable assembly appeared dry and clean.

I've since had another track event and it is still dripping fluid on the cats (it smokes in the paddock) and making big puddles in the paddock. On the way home it actually stopped allowing selection of first gear and second is tough, too. The rest of the gears are fine (I suspect it's just low on fluid, at least that's what I'm hoping).

Most of the "wet" area is the back of the engine block, and the are around the right side output shaft. This is what led me to replace the RH output shaft seal. There are lots of stories about the ring gear pumping fluid up the speedometer cable out of the top, but that area appeared to be dry. I'm not ruling this out, though, and I'm interested in people's experience with this and how to go about checking it.

 

[Ishodu]

Is your tranny vent in place yet? Of so check to see if its plugged up.

 

[Bizzy]

Possible places for an MTX tranny to leak are:

Axle seals
Shift shaft seal
Input shaft seal
VSS connection
Case (anywhere the 2 halves meet)
Vent


All can be checked from the outside with the exception of the input shaft seal.

Now, question is this. Are you sure it's coming from the tranny? Do you use tranny fluid in your rack by chance? You don't have any "air vents" not factory installed in the case do you?

Let me know if you need my assistance, I'm here if you need me.

 

[rangerj]

Trans fluid between the back of the engine block and the trans indicates an input shaft seal leak. It is very common for these seals to be OK and not leak until you stop the car, like on the paddock.

At a track event you are most likely getting the trans fluid hotter that under normal driveing conditions, so the leak does not occur under normal driving conditions. Eventually the leak will occur on a regular basis. it is a matter of time.

Bizzy is right about the vent. It has to vent the pressure or the fluid will be forced out of the seals. Check this first as it is the easiest to do. rangerj

 

[Shoaz]

I have a hose on the vent that terminates at a filter that's higher in the engine compartment. The leak has been worse since that's been installed, so I'll double check that that's not plugged.

Otherwise the tranny is stock, it's never been opened up since new, so no other modifications and the stock open diff.

The power steering fluid level has never moved since the leaks started, but the tranny is low sometimes, so I've been pursuing that as the source of the problem.

Bizzy: any hints on checking whether the VSS is okay?

 

[Ishodu]

If the vent you have there is plugged this could be causing a increase in pressure when the tranny temps are high. So it could be forced out the seals then that usually wouldn't leak.

 

[Bizzy]

I have a hose on the vent that terminates at a filter that's higher in the engine compartment. The leak has been worse since that's been installed, so I'll double check that that's not plugged.

Interesting. I'd be interested in hearing the purpose of the tubing and filter. To be quite honest, with as poor as the oiling system is in the MTX tranny I don't understand why a filter would be required, especially with it located higher up in the engine compartment. I guess if I understood the purpose it might make more sense to me.

Bizzy: any hints on checking whether the VSS is okay?

The way to check the VSS would be to disconnect the cable to the stalk. Then remove the vss from the transmission. The top of the drive gear will be seen then. You'll want to look there for any pooled up tranny fluid. It is inset into the case a little bit so if you're leaking there you'll see it.

If that is the culprit, then you'll want to remove the drive gear from the trans housing. It is held in the transmission with a long thin bolt that breaks easily sometimes, so be careful. They get crudded up badly up here in the northern states, it may not be as bad down there. In any case, they do break easily. Once that bolt is removed then slip a flat head screwdriver under the lip (it's on the top, you should be able to see it if the top is clean) and pry up. It may take some budging so just keep at it until it starts to raise up out of the case.

Once the drive gear is clear of the case you'll see a black rubber donut gasket that goes around the body of the gear. There is another small one at the top where the VSS dohicky fits into the drive gear. If you take that one out the entire plastic part of the drive gear will separate from the aluminum housing. If either of the gaskets are loose or damaged then replace them. I think that Buna would carry one in the right size. McMaster-Carr carries Buna if you need to go looking for one. I have used ones here if need be also.

Personally I'd start with your tubing and filter contraption to see if it's leaking. Don't forget to let me know the details. I have an idea of what you're doing, but I'd like hear more about it. I may also have some ideas to pass your way if you're doing what I think you're doing.

 

[Shoaz]

The tube and filter are to keep fluid from puking out the vent at the track. Otherwise it drips down the side and spews all over. This way it just gets a little reflux up the tube and goes back into the tranny, and it can still breath through the tube via the filter, which just keeps crap from going down into the tranny through the vent.

I did just verify that the tube and the filter are very clear. No problems there, which is a bummer as that would have been easy to fix.

The VSS and speedo cable are still very clean, and there's no puddling in the top of the tranny there. I need to get the car off the ground to check the RH output seal again and see if I can tell where the fluid is coming from, and get some more fluid in to see if that solves the 1-2 selection problem.

I'm certainly open to ideas here, this one's getting frustrating.

 

[AutoSHO]

I second the input shaft seal - if it looks like it is around the back of the engine block I suspect it is very possible for it to come from inside the bellhousing.

A new transmission with a Quaife in it would solve all your problems!

 

[Bizzy]

I'm certainly open to ideas here, this one's getting frustrating.

I can understand your frustrations completely.

I don't think even under harsh track use that the tranny should be blowing that much fluid out the vent, I've never heard of it anyway unless the trans is severly overfilled. Some is normal, but not enough to leave a puddle.

Sending you a PM.

 

[Shoaz]

You're right, when the vent pukes, it's not enough to leave a puddle, just make a mess down the side of the tranny into the wheel well. The hose is just to prevent that.

The puddles I'm getting are from somewhere else, since the vent hose and filter are dry, and the area around the vent is reasonably clean.

I suspect that if it were the input shaft seal I'd be having clutch problems as well, which I'm not.

 

[revhardSHO]

You're right, when the vent pukes, it's not enough to leave a puddle, just make a mess down the side of the tranny into the wheel well. The hose is just to prevent that.

The puddles I'm getting are from somewhere else, since the vent hose and filter are dry, and the area around the vent is reasonably clean.

I suspect that if it were the input shaft seal I'd be having clutch problems as well, which I'm not.

When I pulled the blown MTX out of my 92 I noticed a nice hole in the bellhousing side of the case, a puddle of ATF in the bottom and spatter all over the clutch/engine block. Granted it was almost a brand new clutch, but the ATF didnt seem to effect it at all. Still holds really well.

It also could be that your "prevention" hose is too long and thus creating undesired back pressure in the case. I would at least try running the stock vent for a track day and seeing how that does again.

 

[Shoaz]

It also could be that your "prevention" hose is too long and thus creating undesired back pressure in the case. I would at least try running the stock vent for a track day and seeing how that does again.

I'm not sure how it could create a pressure problem in the tranny if the hose and filter aren't creating a restriction. If the pressure were too high it'd continue to push air/fluid up the hose, and if it were too low it'd just suck in whatever is in the hose (whether it were air or fluid or both). Do I misunderstand you?

 

[revhardSHO]

I'm not sure how it could create a pressure problem in the tranny if the hose and filter aren't creating a restriction. If the pressure were too high it'd continue to push air/fluid up the hose, and if it were too low it'd just suck in whatever is in the hose (whether it were air or fluid or both). Do I misunderstand you?

No, you are correct, I was using the wrong logic.

 

[yamahaSHO]

I second the input shaft seal - if it looks like it is around the back of the engine block I suspect it is very possible for it to come from inside the bellhousing.

A new transmission with a Quaife in it would solve all your problems!

From what I remember, I don't think it was in a spot that could be the input shaft.

 

[Shoaz]

Latest update:

The tranny was about 1/2 quart low, which isn't as bad as I'd thought it would be.

A SHO deity emailed that one possibility is a leak between the case halves above the ring gear. I refilled the tranny and used some race tape to hold a folded shop towel in the area of the suspected leak, then took a test drive to see what I could find out.

After the drive the towel was still dry, so either I need to hit speeds higher than about 85mph to make it leak there, or that's not the problem.

Also, it's still having trouble getting into first and second gear. It's a little better than it was, but not much. It'll go into gear when the revs are matched exactly, i.e., I can get it into first by letting it roll down from neutral, but I still can't get it into first gear from a dead stop.

For the last several track events it's had el-cheap-o Pennzoil Mercon ATF in it, and I'm wondering if that isn't possibly part of the gear select problem (although I don't know why it would be). Has anybody else had any trouble with this stuff? I could pump it out and put something else in, but don't want to go to the trouble if nobody else has had any problems with it.

Any thoughts?

 

[sdpatt]

A leaking MTX output shaft seal will show a fluid trail from the seal to the bottom of the transaxle casing mating surface (lowest point of the trans), but will most likely not wet the back of the engine block or the cats. You really need to determine where the leak is coming from before removing or replacing anything.

Installation of the output shaft seal requires an appropriately sized tool or PVC pipe to prevent damaging the metal structure of the seal. If this seal carrier is bent, the seal will not function properly and will leak. Installing the seal is hard enough to do on the driver side seal when the trans is still installed. It must be very difficult on the passenger side seal. See my experience when replacing the driver side seal during a CV shaft replacement here.

After having the transaxle apart in my own hands and inspecting the internals, I have a hard time seeing how any transaxle fluid could reach the vent if the fluid is at the proper level. The fluid only covers the lower four (approx) inches of the casing. I've heard the stories of the fluid "puking out the vent," but I just can't see how it gets there.

 

[TankII]

Isn't the vent out the side? If so, putting a hose on it covers the vent up, making the pressure worse.

TankII

 

[Shoaz]

Isn't the vent out the side? If so, putting a hose on it covers the vent up, making the pressure worse.

The vent is on the top on the driver's side end. The hose just makes it breath from a higher point and give the fluid splash a place to go other than out.

 

[TankII]

Don't forget the shifter shaft as a leak point...


Yes, I know the vent is on/near the top. I meant the hole for the actual venting process to take place is on the side of the vent nub.

TankII