As I write this I'm riding in the truck taking me and my car back home after a track day. Well, not because the car won't drive but because it's not street legal...

Anyway, near the end of the day it was pointed out that my transmission was leaking pretty badly so I had to stop driving for the day.

I was was wondering if this might just be blowby and if my transmission needs a catch can, or whether something's might have broken. What are some common causes of a leaking transmission?

 

First assumption would be transmission oil overheating.
Trans + Diff Cooler needed?

 

Could also be sloshing with it pulling a lot of G's. Check if it's overfilled. Also, see if you can find where the leak is coming from, if it's from the breather on top or out of the shifter housing.

They do make trans spacers that add extra capacity to the trans. More oil means the system runs cooler.

Dale

 

Yes, check the transmission fluid level. And, I'm sure you know, make sure you use each transmission plug for its intended purpose.




Don't use "C" as the fill plug:

 

Assuming the level is correct and all plugs are in place, then no there isn't any blow by or need for a catch can. Something is wrong. Look for leaking seals, wrong level, or missing plugs.

Yes this trans can benefit from cooling and/or more fluid volume but overheating the fluid will lead to viscosity breakdown and bad shifting before somehow boiling out.

 

Wait, wut? Which one is for what?

 

Remove A and B to drain, fill at port D.

The fill port is a square plug on the side of the trans, the other plug on the side is a hex-shaped plug. If you need a special tool, that's not the fill plug.

For the plugs that don't have a crush washer, clean all the old crap off the plugs and wrap in Teflon tape to seal.

Idemitsu has a gear oil that does really well, I recommend it. May also be worth looking into a transmission spacer to get some more capacity if you're doing track events. But, first step is figuring out if and how much of a leak you have.

Dale

 

I just got charged an ***-ton for cleaning my oil leaks and installing catch cans to the diff and tranny. Hopefully that stops the worst leaks. Apparently my engine and power steering is also leaking.

I may need a new o-ring for the oil filler cap?

 

edit

 

Just an update, I have blown about 300-400 ccs of gear oil into my transmission catch can (or the floor pan) every track day I've done in all the years since, but the transmission doesn't seem to care, so it must have been overfilled. Hopefully it'll eventually stop doing this... lol

The guy who did the work on my car is constantly overfilling things like engine oil and brake fluid, so I assume both my transmission and differential leaking were because of overfilling. At least the diff stopped spewing fluid pretty quickly.

 

Seems like he’d almost have to be trying to overfill either one very much. Is he tilting the car on its right side or standing the car on its nose? I still suspect the issue is expansion.
I think I’d put the car level on jack stands and check the levels on both before another track day.

 

More likely he just filled it from the C plug instead of the D plug, doing so overfills by roughly 1/2 a quart. My FD's previous owner did this, and I discovered this shortly after buying the car & driving it around - oil was spewing from the vent and getting literally everywhere, making me think I had a major leakage problem. Drained it all out and refilled from the D plug, no more leakage issues.

 

Yeah, this is probably what happened… plus he probably still managed to overfill it beyond that, somehow…

 

I guess I’m not following you…afaik there are two drain plugs for the transmission but only one fill plug. In the diff only one drain and one fill. Seems kind of hard to screw up….but maybe adding coolers changes things?

 

There's only one fill plug, but there's another plug of unclear purposes located higher up that could easily be misconstrued as a fill plug. The FSM procedure assumes you know the difference.

 

The socket-head plug is pretty far away from the square head fill plug. Otherwise…“Remove plug A (with washer) and B. Drain into suitable container…”. Not certain but figured ‘B’ drains a compartmentalized section, used for a windage type purpose maybe? Or maybe just due to the shape of the housing somehow. Before the edit you said “only one drain plug” hence my response)
Regardless, two drains, one fill, which is the highest of the three. Seems like the FSM assumes they can read and follow pictures. But again, maybe adding a cooler complicates.

 

Unless he was working on the car with it sitting at an angle, I don't see how that's even possible... If the car was level, then oil would simply fill up to the level of the bottom of whatever "fill" plug he was using, and then start spilling out from there.

Correct, but if you go back to the FSM diagram, only the "D" plug is supposed to be used for filling the trans. The "C" plug can be mistakenly used, but since it sits higher in the case than the "D" plug, with the car level if you fill it up to the level of the "C" plug, you'll end up overfilling the tranny.

Two drains is correct, but only 1 plug is the correct fill plug ("D" in the diagram), which is the LOWER of the 2 possible "fill" plugs ("C" & "D"). I'm basing this on the FSM diagram, and on the empirical evidence from my car's PO filling to the level of the "C" plug, which grossly overfilled the tranny and caused it to spew oil from the vent in use. Not sure why the "C" plug is even necessary, other than as a air vent to help speed up the draining process perhaps?

 

There's always a chance they jacked up the car from the side or the front and did it that way. I'm not sure if they did it on their lift.
Let's just say I have lost a LOT of gear oil into the catch can, and the transmission is still working... Though it's probably time to check the level.

His overzealousness with engine oil previously caused me similar problems. It made me think maybe my engine or turbo was on the way out. Being very specific to not overfill it solved the problem.