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I want to learn how to change my transaxle fluid. Actually top it off because it’s leaking so a couple questions:

1) which is the fill hole and the fill check hole (picture included)

2) what size is the fill check hole allen and what’s the best way to remove it

3) what size is the fill hole bolt

4) what’s the best way to get the transaxle to stop leaking other than flex tape haha. IMG_3203Bolts have been tighten.

Thanks for helping. Really want to take care of it


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1) On my -2, the check hole, and fill hole are the same…. Left side, down low…. You can see it in your picture…

2) IIRC, it’s a 17mm Allen.  You can get the sockets from VW (Bug) suppliers.  They fit a 3/8” ratchet.

3) Fill the side (with a flexible hose) until it starts dribbling out.  You can use Teflon tape on the plug.

4) You can just dip the whole transaxle in flex-seal!  Just mask off the two output flanges, the breather vent, and the clutch inspection port!


I have one of these funnels that works great for filling the ZF.

Right Angle Funnel


Other similar options are readily available, or even a tranmission funnel with a flexible tube.

Generic angled Funnel


Transmission Funnel


I used Castrol 90 wt Hypoy Gear Oil if I recall correctly.  Be sure to let the bottles rest in a bucket of HOT water for a bit so the oil flows a little easier.  Allow the oil plenty of time to slowly ooze through the internal passages of the ZF to the other cavities.

Also, the 17mm VW oil plug sockets are readily available at your local O'Reilly Auto Parts, or Autozone.  Or, from a number of online sources.


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Last edited by garth66

..I use to use the funnel with a hose...until I drilled and tapped the plug 3/8" NPT, for a elbow, adaptor and a oil temp sensor. I can testify, the sensor has no problem getting heated from oil splash. Also the air cavity will have the same temp. You should have kept your sensor in place, but you would always see a normal temp of 187F to 194F degrees! Just coming off a high speed run on the Freeway!

Enjoy the photos.

The TOP gauge sees the engine coolant temp, separate from the Oil Temp gauge at the BOTTOM of the row. The Mini Toggle switch at the very Top of the panel...switches the oil temp gauge, Left for Engine oil, right for Transaxle oil temps.

The gauge at the very for right, UN-mounted is ambient temps. The sensor is suppose to be outside the car, at this moment is in cabin. Mounting In process.

The thin Gauge directly in front of the CD Deck is a digital for 'Fuel Pressure'. Very Safe way to do it.

The Volt gauge is at 11 volts until engine is fired then charges at 14.1 volts. The Oil pressure is at 'LOW' with engine off then, when running, shows 51 PSIG, but the (1) Filament has burned-out long ago.

The row of 4 gauges is, from top to bottom Engine Water Temp, Engine Oil PRESSURE, VOLTS, Eng/Xrans Oil Temps.

One photo shows Upper left corner Digital Tachometer, Aircraft Clock will show 3 at will, Chronometer, Elapsed Timer, Real Time.

Why Digital gauges instead of Analog??

With Analog gauges: they take time to Read! First you must identify the gauge, what the Lines and Numbers represent, last at which line is the Needle pointing to, or in between...Exactly!

With Digital Gauges...first, RED Light Does Not Spoil your Night Vision, why they use them in Aircraft. And they are bright or dimmable. All you are required to do is Identify the Gauge you are looking at, and the Exact Numbers are right there!! Accurate To the 0.1!

Ask all the questions you wish.

The Engine Temps would run over 250F (gauge Blinking), cruising the Freeways at 85 MPH,abc eng tmpd eng tmpefghjl Constant. When I turn on the Cooling Fan on the Rear Cooler, Oil temps drop to 227F, and that reading is taken 'Before' the Cooler, after circulating through the Engine!  Believe it or not.



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Last edited by marlinjack

...when you wrap Teflon tape, you must do it in the direction of 'Tightening' as the plug is screwed in. The plug in the photo has been wrapped in the opposite direction, and will loosen as it is screwed in. This alone can account for leaks. From My experience, Many Machinists and Mechanics don't know this. And in Aircraft, the Minimum is 3 Turns. And be careful not to tighten the plug too tight, or you can Crack the Case!! Teflon tape makes it very easy to Tighten-Up the Plug!

My Plugs Never Leak.

Just My 2 cents


P.S. When I do the Oil Pan Drain Plug, I use a Rubber 'O' Ring AND Teflon Tape. NO Drips, And those Plugs Will Strip Easily!! The Designers Should have used a NPT, Tapered Thread, can be Tightened and near impossible to Strip. I Repaired a few Stripped Pan Drains, for 'jiffy Lube'. I would Braze-in a Brass Adaptor and use a Brass NPT Plug! Saved them a Lot of Money! And with Tape, Sealed Very Well.

Remember! 3 Turns on the Tape, Tightening!

Last edited by marlinjack

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