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Is it bad I overfilled my transaxle?

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RallyEclipse98

15+ Year Contributor
967
28
Jul 31, 2007
Dallas, Texas
Story time…

It was a few days before Christmas. I decided to change my transaxle fluid because I wanted to check it off my list before the end of the year. It was cold. I was cold. I hurried through the task. What I did was I jacked the car up in the front, drained and filled the fluid. In order to get the right fill amount, the car must be level. So I let down the jack, looked under the car, and no fluid ran out of the hole. But I had used well over the required amount. Strange, I thought. I know I had spilled some. Maybe I spilled a lot more than I thought.

Fast forward to today. I’ve driven the car about 3,000 miles since Christmas. Today I gave it about 75% throttle (I usually baby the car) and the transmission… slipped. Each time I stepped hard on the pedal, it acted like an automatic waiting to downshift. The revs would shoot up as if in neural and then they would fall as the tranny would finally slip into gear. It did this in every gear at high throttle.

The only other bit of strange I noticed is there’s now a loud whistling out of the exhaust at high throttle. I doubt they’re related but just wanted to get it out there. Maybe it’s just an exhaust leak. The whistle comes right out of the end of the exhaust tip it sounds like.

Anyway. I sat the car on (4) jack stands today to check the fluid. I pulled the fill plug to see if I had low fluid. Fluid came gushing out. A lot of it.

Turns out, I must have put the fill plug in BEFORE leveling the car the night I filled it. So yes, I was running around for 3,000 miles with about ¾ of a quart extra, I'm guessing.

Could this have caused my slipping problem? Yes, I could just go drive the car but I’d like to get this resolved while it’s still on jackstands in the shop. Plus, if the synchros are bad or something I don’t want to make it worse by driving more.

What do you guys think? And yes, I was stupid but did overfilling my transaxle fluid cause my transmission to slip??
 
well IMO overfilling it a little wont do that. the slipping problem would be more towards the clutch and flywheel. Granted overfilling the trans is not what you want to do but I cant keep thinking that its not related to that issue you have of slippage.
 
Manual tranny cars are not as prone to bubbles and seals blowing when over filled. It might effect the cooling of the fluid, but shouldn't make the car feel like it is slipping. Going with born2tune, clutch is the culprit. Hope the whistle isn't actually your throw out bearing or a backed out bolt on the flywheel. Good test for the clutch is to put car in third gear while running, let off clutch slowly giving no gas. If car pulls away, time for a new clutch, if it dies then the clutch is good. Do this a couple times to make sure.
 
Manual tranny cars are not as prone to bubbles and seals blowing when over filled. It might effect the cooling of the fluid, but shouldn't make the car feel like it is slipping. Going with born2tune, clutch is the culprit. Hope the whistle isn't actually your throw out bearing or a backed out bolt on the flywheel. Good test for the clutch is to put car in third gear while running, let off clutch slowly giving no gas. If car pulls away, time for a new clutch, if it dies then the clutch is good. Do this a couple times to make sure.

I searched but not 100% sure. Is there a way to check the clutch adjustment before I get the car down and run it through your test? Adjusting the pedal won't matter, will it? I just wanna make sure she's ready for the test. :D
 
The clutch is a closed hydraulic system. Adjustment of the system is made at the master cylinder which I believe is what you are referring to when you mention the clutch pedal. Adjusting the master cylinder in or out will affect how far the slave cylinder moves due to the transfer of hydraulic fluid. After that is where it becomes mechanical movement of the clutch assembly starting at the fork and fulcrum. The only other adjustment that can be made is shimming the fulcrum if the fork is not far enough over to the driver's side.

The clutch adjustment procedure can be found here:
You must be logged in to view this image or video.
 
Get the whole car up on jacks, put it in first with clutch in, rev to 7K and watch your wheels.
IF they spin your clutch is dragging and you need to bleed the system more or adjust your MC rod. To find the sweet spot, I would adjust the rod until you can't push the slave rod/ fork in by hand. Then back the rod out 1/4 turn. Then do the above clutch drag test and adjust with more bias towards the clutch drag test.

This is more of an issue with heavy pressure plates.

Also, I'm not a big fan of stalling out my car multiple times to diagnose a problem.

As for overfilling: It should push out the rubber breather up top before blowing seals. And it won't really do anything besides give you a little scare and make a little mess.
 
The clutch is a closed hydraulic system. Adjustment of the system is made at the master cylinder which I believe is what you are referring to when you mention the clutch pedal. Adjusting the master cylinder in or out will affect how far the slave cylinder moves due to the transfer of hydraulic fluid. After that is where it becomes mechanical movement of the clutch assembly starting at the fork and fulcrum. The only other adjustment that can be made is shimming the fulcrum if the fork is not far enough over to the driver's side.

The clutch adjustment procedure can be found here:
You must be logged in to view this image or video.

Is the procedure the same for the nonturbo 2g tranny? If so, I'll do this today. Seems straightforward. Thanks for including the video.

And one thing I forgot to mention earlier in the post (probably irrelevant) is I disconnected the neutral safety switch. After doing that was the first time I noticed the slipping.
 
Get the whole car up on jacks, put it in first with clutch in, rev to 7K and watch your wheels.

That doesn't seem like a very good idea. If the clutch is dragging you'll notice it right away and free-reving the engine to redline is never a good idea.

The most likely cause of the slipping behavour is a blown clutch but it can feel like the clutch is slipping if there is a problem with the coupling to the transfer case or rear diff on an AWD car. I once popped a rear axle out of the diff and it felp like the clutch was clipping as power was transferred to the now freespinning wheel until the VC's kicked in.
 
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If the clutch is dragging you'll notice it right away...

I'll notice it right away? The car is still on jack stands. Can I just push the clutch in, give it some light revs, and see if the wheels move?

If so, readjust the clutch using the aforementioned video? If that doesn't work, put in a new clutch... eventually.
 
I'll notice it right away? The car is still on jack stands. Can I just push the clutch in, give it some light revs, and see if the wheels move?

If so, readjust the clutch using the aforementioned video? If that doesn't work, put in a new clutch... eventually.
No...You want to put it on the ground and put the car in first and hold the clutch pedal all the way down and give it like 7k rpms, and if the car creeps forward, you're clutch is dragging, but most likely your clutch is slipping, which also could've been premature from a dragging issue.
 
I found an old post from DarkOne on DSMtalk. He said there's no way to adjust the master or slave cylinder on a 420a trans. But I can adjust the clutch pedal. Anyone know the proper adjustment for that? I can't find any good info. on it. Just a bunch of hearsay.
 
I guess I doubt the clutch pedal height would have ever gotten out of adjustment so messing with the pedal probably isn't smart.
 
Sounds like differing opinions.
On the ground, you won't notice the wheels move until they break the threshold of torque in getting the weight of the car moving forward. On jack stands there's no torque threshold to overcome.

I can't think of any other way to check for clutch drag. Please inform me.

If I didn't trust my car to free rev to 7k one time I wouldn't drive it.

But anyways, it is indeed most likely a worn clutch to begin with. Adjusting for drag probably won't do you any good.
 
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