spender

I've recently discovered that I have a transmission leak in my 2003 C4S Tip. It's a very small one, a few drops a week (I have an epoxied garage floor I keep clean enough you could eat off it, so this is easy for me to track). I believe it may have been related to my transmission mount, which was cracked, but just replaced (I'm assuming that the trans might have jumped around more than it should and this may have stressed parts, etc.). I first noticed the leak in the early fall. It hadn't even caught the attention of my mechanic, probably the best independent in town (and I get my oil changed often as I have an aftermarket warranty that requires frequent oil changes). My car exhibited no other "transmission problem" symptoms - it sometimes had a clunk or slip when taking off from a standstill at a stoplight, but that's it. There are no other symptoms as far as I can tell that the automatic transmission is having problems (grinding, slipping, etc.), and my mechanic says that right now there are no real mechanical symptoms.

Anyway, last time (when he noticed the cracked trans mount), he changed the transmission pan filter and seal, yet it continued to leak, maybe a little more than before (but still not much). When I brought it in last time so he could change the trans mount, he said that it might be transmission seals acting up. Problem is that despite the Mercedes 722.6 automatic transmission still being in production for Mercedes, Porsche, Jaguar and Chrysler cars, the seals (for the Porsche one, anyway) are not available anywhere for purchase. Even if they were, it's a huge job in terms of hours to even get this transmission on the floor out of the car.

My mech is being pragmatic about the issue - he's said that we should just monitor it for the next little while. He says the automatic transmission is pretty bulletproof, apparently, and they do not fail often. He says that if the leak gets worse, we may go in and it is possible for him to rebuild the seal. He has discouraged me from jumping to conclusions too quickly, and says I should resist the urge to run out and find a used/rebuilt transmission on the aftermarket (I asked him if I should)... but that hasn't stopped me, and thus my questions to the "group".

My car currently has the A96/35 Tiptronic S transmission (manufactured by Mercedes for Porsche), which was in the 2002 to 2005 Carrera 4 and 4S models. The 2000 to 2005 Turbo Tiptronic models had the A96/50 transmission, which is the same on paper (as far as I can see in Adrian Streather's book), except the final drive ratio is 2.89:1. Of course, these are both AWD models.

Further to the above, I have started hunting around for another transmission, and at an early stage I have noticed that there seem to be a lot more Tiptronics transmissions from Turbos (the A96/50) that are available on the market.

Thus, my question is if anyone knows if my 2003 Carrera 4S, which originally carried an A96/35, would be compatible with an A96/50, designed for the Turbos. Anyone?

Torontoworker

He is trying to save you money. These people are few - most want you to spend money - everything is an emergency. Go with your indy's advice.

Pac996

Engines and transmissions will leak at times. I wouldn't doubt with the amount of cold you get that the expanding fluid and air makes enough pressure to cause some fluid to be pressured out through the weakest areas. Try cleaning to monitor and clean again when it warms up to check for the what class of leak if any. Trans fluid expands a lot when it heats up so...........

geetee

No prior experience with these guys but vertex rebuilds the non turbo tips. Might want to to look into that also...if/when it fails...just another alternative

htny

The MB units (my experience is limited to e55 & 430, sl, clk55) have a documented issue with leaks from a faulty o ring in the plug where the Transmission Control Unit wiring harness connects to the vehicles wiring. I haven't taken apart the specific unit on the 996, but I can tell you the fix should be extremely simple. Get your hands on a shop manual for this particular vehicle model year, and locate the harness/plug. If it's leaking from the plug you should be able to fix for about 15-25 dollars all by yourself, I've done it a couple of times and it's really not a big deal.

One thing you MUST resist doing is flushing the fluid. Don't do it. Unless there are serious shifting issues, leave it alone. Don't add fluid unless you acquire a transmission measuring tool (fancy flexible mb dipstick, MB doesn't sell anymore, Chrysler does though).

318touring

Transfer case/box leak?

Got one of those, and been discussed here http://911uk.com/viewtopic.php?t=60919&highlight=

spender

Thanks for your note, why should the fluid not be flushed?

That was the first thing my mechanic did when this issue came up the first time, was check the seal on the transmission pan. In doing that, he had to change the fluid and the filter. I will admit that it seems to have started leaking more since he did this.

htny

so just in case I wasn't clear, the o ring i'm referring to is not the trans pan (although the harness should be close), it's at the TCU wiring harness

RE: fluid,
1) people have not had good experiences changing the fluid in this or any other modern electronic-shifft-plate type planetary automatic. The fluid/filter change is a default convention when maintaining older style shift plate transmissions.
2) these transmissions are extremely, extremely sensitive to the fluid level, and some say potentially adaptive (in some unforeseen way) to the viscosity and fluid characteristics of the fluid as time goes on and particulate matter accumulates (which honestly I have a hard time buying intellectually, but I've seen too many fail or falter after flush to say otherwise) .

722.6 series in general are bulletproof, I tell people not to ever mess with them, they just never break unless you drop them, drive over a rock, or allow leaking fluid to wick up the wiring into the TCU/ECU.

Laura

A common leak from these transmissions is from the nose cone area. This can repaired with the proper gasket, seals and o-rings with the transmission removed. The "replace transmission" offer by the dealer can be avoided.

Frank Urbaniak

I have a 2001 996tt tip where after much time and expense in diagnostics, was found to have leaked transmission fluid from the electrical harness (wicked), on up to the ECU. Is it just the O-ring at the connector that allows this leakage, and how does one prevent this?

808Bill

It's been 8 years since anyone posted in this thread. Not sure the OP issue was fixed and shared. You might have to change the o-ring!

Porschetech3

You need to replace the connector plug that goes into the transmission, it has the o-rings on it. About $20 bucks. Google "722.6 connector " for DIY video's and instructions, part numbers, ect. Common problem on the Mercedes 722.6 transmission..

Ryan996TT

I’m quite certain I have this issue going on right now in my ‘03 996 TT.

Dropped it off at an Indy shop today for diagnosing a leak, and I’ve yet to hear back. I’ll suggest they check this out tomorrow.