What the heck is going on in here? (996 Manual Transmission)

[Chad W]

I have a 2002 996 C2 and I'm in the process of changing the manual transmission oil. I got a kit that included two plugs. When I pulled fill plug out, I was confronted by an odd shaped plug and a circular magnet that is loose in the transmission case (held magnetically to the side). Can anyone tell me what I'm looking and what it should be? My inclination is realign the hole and reinsert the factory plug.

[JFP in PA]

Bad move. You have not removed a drain/fill plug, you have removed the access plug for one of the gear detents instead. As these sometimes have thrust washers inside the transmission, which now may have dropped, you have a problem as if that washer gets up into the gears, your gear box will promptly become a boat anchor.

These are the correct plugs for servicing the gear oil:



This photo shows a typical six-speed Carrera transmission with both the drain plug (insert upper right, yellow arrow) and fill plug visible (blue arrow). You only need a 10mm hex socket in order to remove either plug (insert upper left).

[Chad W]

Thanks for the info. The washer has not dropped, as long as I'm able to center the thrust washer back on the pin and re-install is there an issue?

[BYprodriver]

JFP to the rescue again!

[JFP in PA]

Originally Posted by Chad W

Thanks for the info. The washer has not dropped, as long as I'm able to center the thrust washer back on the pin and re-install is there an issue?

The washer slides onto the "snout" sticking out of the plug, and then the thing you can see inside the trans slides over it during assembly. If there was a washer (not all do, it is used to take up the slack for casting differences on the cases), it is now down in the bottom of the trans. Unfortunately, the only way to know is to pull the box and take it apart to see.

Believe me, you are not the first, and probably will not be the last to make this mistake. You really need to know what you are doing before removing anything on these transmissions; small mistakes can be awfully expensive..............



How to change your manual transmission oil from the factory service manual:

Note: Part numbers sometimes change without notice. Always double check with your supplier that you have the latest part numbers.

Parts you will need:
3-4 liters 999 917 546 00 (Shell) Shell Transaxle (75W-90) or Mobil Mobilube PTX (75W-90)
Approved Manual Transmission Oils
000 043 204 20 Mobil (Mobilube PTX) - 20 liter container
000 043 204 19 Shell (Transaxle) - 20 liter container
999 917 546 00 Shell (Transaxle) - 1 liter container

Note: All are synthetic GL4 and GL5 rated (or "non-conventional processing") oils. GL oils have good light running properties because of their light low-temperature viscosity as well as a high level of temperature stability.

Tools you will need:
Tire ramps or jack
17 mm allen for the fill plug
16 mm triple square with a hole in the middle for the drain plug
Note: Most later cars have an 10 mm allen type plugs - we recommend checking before you start.
3 quart oil catch pan
Torque wrench (optional)

Drain Transmission Oil
Transmission oil should be changed when the engine/transmission has reached normal operating temperature. CAUTION - oil will be hot, take adequate precautions to avoid being burned.

Use ramps or jack up the vehicle at the points provided.
Remove underside panels to access the transmission. (Boxster owners you need to loosen the diagonal braces and then remove the transverse strut member. A little more work on a Boxster. When you put them back they need to have the bolts torqued to 48 ft lbs. (65 nm). See images Image 1 Image 2 Image 3 Image 4 Image 5 ) (images courtesy of scherb)
Place oil collection pan under the transmission (at least 9 quarts). Always dispose of the waste oil in accordance with local legal requirements.
Unscrew oil filler screw (1).
Unscrew oil drain screw (2) and drain transmission oil.
Wait about 20 minutes for all the old oil to drain.
post-2-1132092160.gif
Fill Transmission Oil

Clean oil drain and oil filler screw.
Screw in oil drain screw. Tightening torque: 22 ft-lb.
Fill with gear oil up to the bottom edge of the oil filler opening.
Screw in oil filler screw. Tightening torque: 22 ft-lb.
Install underside panels.


Model/Capacity (approx.)
Manual Transmission
911 Carrera (G96/00) - 2.7 liters
911 Carrera 4 (G96/30) - 2.7 liters
GT3 - 3.3 liters
Boxster (G86/00) - 2.25 liters
Turbo - 3.0 (to 3.8) liters
Front-axle Final Drive
911 Carrera 4 (Z96/00) - 1.5 liters
Turbo - 1.5 liters

[Chad W]

Thanks JFP!

The work is actually being done by my local European specialist. I've known the guy for 25 years and he's very consciousnesses. Obviously he's kicking himself pretty hard right now, but I trust him to make it right.

I've been too busy to do it myself and my thinking was that I don't need to bring this to the Porsche specialist, because I'm not looking for anything diagnostic.

Hopefully the only downside here is that the car spends another day in the shop....

[Chad W]

I just to check the car out and it feels like the centering spring is no longer connected to the shifter. The mechanic is going to spend some more time with it later this evening and inspect further. Obviously I will not be test driving or taking the car back until this is fixed.

Are there any other potential signs that a washer was present and is now loose in the gear box?

Would it likely fall to the bottom of the box and be in the area of the drain plug? Thinking that it could make sense to drain the oil back out and try to see if anything can be found through inspection scope or magnet.

[JFP in PA]

Originally Posted by Chad W

I just to check the car out and it feels like the centering spring is no longer connected to the shifter. The mechanic is going to spend some more time with it later this evening and inspect further. Obviously I will not be test driving or taking the car back until this is fixed.

Are there any other potential signs that a washer was present and is now loose in the gear box?

Would it likely fall to the bottom of the box and be in the area of the drain plug? Thinking that it could make sense to drain the oil back out and try to see if anything can be found through inspection scope or magnet.

The thrust washer is like a light bulb; it is either there, or it isn't. It simply spaces out the detent device you see dangling inside the gear box when an assembly check say it is too far towards the case, then the washer is used to take up the slack. To my knowledge, there is no way to tell if the gearbox had it or didn't.

As for going in the drain hole, nice idea, but the thrust washer is larger than the drain opening, so you are not going to get it out that way.

[Chad W]

Originally Posted by JFP in PA

.

As for going in the drain hole, nice idea, but the thrust washer is larger than the drain opening, so you are not going to get it out that way.

I think I'm following you here. My thought was not that you'd be able to get it out, but you'd at least know it's there before deciding to take the gearbox off and go fishing.

[JFP in PA]

Originally Posted by Chad W

I think I'm following you here. My thought was not that you'd be able to get it out, but you'd at least know it's there before deciding to take the gearbox off and go fishing.

i would give that a "maybe"; there isn't much excess room below the cluster and synchronizer "tree" inside the case, which is how it kicks up the oil to lubricate and cool the assembly, so it is not going to be easy to get in there to look. It is kind of tight in there.........

[Chad W]

Thanks for the clarity, that makes sense!

[Chad W]

My mechanic called in a favor from a Porsche specialist he knows. The specialist confirmed what you said and the gear box is getting pulled and taken apart to remove or ensure there is no washer there.

[JFP in PA]

Sorry to have to have been the bearer of bad tidings, but you need to be careful when working on these cars; small mistakes can result in monumental repair bills..................

[Chad W]

Bearer of bad tidings? You're the saviour of transmissions! Thank you.

[yelcab1]

Oh $hit....

[manbridge 74]

Perhaps he could insert a 90 degree bore scope and see if the washer has fallen or if there was one there.

[tx996tt]

Hi All,

I realize this thread is 4 years old, but I made the same mistake yesterday replacing gear oil in my 996 Turbo while the transmission was out to install a new clutch. Does anyone know if the G9650 transmissions also have the potential thrust washer? There is spring tension so maybe there was no thrust washer used on the G9650 transmissions found on the 6 Turbos? Wishful thinking here I know... Appreciate any feedback. Also, does anyone have a link to disassembly instructions?

[JFP in PA]

Originally Posted by tx996tt

Hi All,

I realize this thread is 4 years old, but I made the same mistake yesterday replacing gear oil in my 996 Turbo while the transmission was out to install a new clutch. Does anyone know if the G9650 transmissions also have the potential thrust washer? There is spring tension so maybe there was no thrust washer used on the G9650 transmissions found on the 6 Turbos? Wishful thinking here I know... Appreciate any feedback. Also, does anyone have a link to disassembly instructions?

Yes, there is a thrust washer, and as for assembly instructions, Porsche stopped publishing them more than 20 years ago, everything is now on the PIWIS system, which requires a subscription.

[tx996tt]

JFP,
Thank you for your help - very much appreciated. I believe the thrust washer in question is #8 in the diagram? Removing the bearing screw #10 allows the selector arm #7 to pull away from the case and the thrust washer #8 drops into the case? The thrust washer is 25mm OD and no way to fish out the bottom. Note: the diagram is for a 996 GT3 Cup car as I cannot find anything on the 6T trans.

[JFP in PA]

Looks about right.