Tiptronic transmission service

[crwarren11]

I'm recovering from an intermix issue caused by a failed ATF cooler on a 2000 Boxster. Upon emptying the ATF and removing the pan and filter, it has become obvious that the lovely milkshake intermix is not easily removed. I have let it drain for a couple of days now with the filter removed, frequently wiping down the underside of the transmission, and it just keeps coming. Question is, is there a good way to "flush" out all of this milkshake out of the transmission?

[JFP in PA]

I'm recovering from an intermix issue caused by a failed ATF cooler on a 2000 Boxster. Upon emptying the ATF and removing the pan and filter, it has become obvious that the lovely milkshake intermix is not easily removed. I have let it drain for a couple of days now with the filter removed, frequently wiping down the underside of the transmission, and it just keeps coming. Question is, is there a good way to "flush" out all of this milkshake out of the transmission?

This is not going to be easy. About half the contaminated fluid is in your torque converter, which does not fully drain by pulling the pan. Ideally, you would want to use one of those pressurized flush through systems that may service centers use because clean fluid pushes out the contaminated. Unfortunately, I am not aware of any flush system that would work on your Tip because the aftermarket units connect via the ATF lines to the cooler, which your Tip does not have. You may want to talk to someone that rebuilds Porsche Tips such as Vertex.......otherwise it may have to come out.

Edited August 15, 2011 by JFP in PA

[crwarren11]

There is an ATF cooler and I can easily access the supply and return lines to/from the ATF pan. In fact, I will be replacing the ATF cooler as soon as my new one arrives. Once it is out, I susupect I could add ATF under pressure into the return lines and hopefully flush out the nasty stuff based on what you said. Does that seem correct?

[JFP in PA]

If there are lines, you have a possible way to do this. I'd suggest doing some searching on how other OEM's that use the Tiptronic (VW, Audi, Mercedes, etc.) flush and purge these transmissions in their cars as which line the new fluid goes in, and at what pressure, is important. An OEM dealership that works on these transmissions may be able to do this for you as the hardware for fluid exchange systems is often in the $3-$5K range, and the adaptors to attach the exchange units are specific to each transmission.

[crwarren11]

One of the more interesting suggestions I found was to perform the refill procedure with the return line from the cooler disconnected to empty into a bucket. The sump would then pump the new fluid into the system (including the torque converter) while expelling the old fluid out of the return line. Would probably require more ATF, but would hopefully prevent having to do another full service in a month or two.

[JFP in PA]

Update

I was sufficiently perplexed by your comments concerning having external lines, that I got out the OEM service manuals for the Tip, and after reviewing them, asked a customer with a 2001 Boxster with a Tip to bring it by the shop so I could look at it (I can honestly say that we do not see that many Tips, but this has shown that I need to pay more attention to how they are set up). Here's were I now am on this topic…..

The only external lines you should have on the Tip are coolant lines that run engine coolant to the trans case below where the cooler mounts, and then return it to the engine from the other side. The coolant then enters the cooler from the bottom, as does the trans fluid (it is a closed, self contained heat exchanger unit,much like the engine oil cooler, but with out the air bleed line that goes from the top of the engine oil cooler to the coolant surge tank). All of the transmission fluid remains inside the cooler or the gearbox, there are no external fluid lines or connections:

So, at this juncture, I have to return to my original opinion in that I cannot see a way to easily connect an external transmission fluid exchange unit and pump fresh fluid through the system to remove the water contaminated fluid. This is not going to be easy……

[Dale_K]

I don't know the answer from personal experience but I see some external lines that look like they might be trans fluid in these two pictures.

[JFP in PA]

Those large lines are the lines carrying coolant to and from the heat exchanger, which you can see in the right picture; there do not appear to be any external trans fluid lines on the Tip that you can easily connect to.

Edited August 16, 2011 by JFP in PA

[crwarren11]

Well I'm glad I can provide some intrigue at least! I was working off of this diagram and what I thought I could see from underneath the car. I got into removing the catalytic converter yesterday, which turned into a real pain, so haven't quite finished that step yet. Once that is done I should have a better idea of which of these lines I can access. I'm hoping, of course, to be able to leave the oil return line open, or disconnected somehow, to empty the system. I have a clear view to the heater valve (item 12), so figured I could identify each of the lines. Honestly haven't gotten that far yet, though.

16 is water supply line

17 is oil return line

18 is oil supply line

21 is water return line

The repair manual is not very helpful on this one:

Side question: do the oils from the differential and the transmission mix anywhere or are they closed systems in the Tiptronic? It sounds like in the manual transmissions that these systems use the same oil, but in the Tip they are different, and I'm assuming completely segregated?

[JFP in PA]

Yes, with the Tip the dif oil and trans oil are kept separate (the dif uses a Hypoid gear oil).

[crwarren11]

Great, thanks.

[JFP in PA]

The oil supply and return may be a possibility, but I am not sure how you would connect to them and hold significant pressure during the fluid exchange, or if they would allow you to fully flush everything, including the converter which is where the major portion of the fluid resides........

[crwarren11]

Yep, I understand, but we'll try to rig something up to see if we can get some of it out. Otherwise I'll be in for another full ATF service very soon!!

[crwarren11]

Ok, I definitely see what you mean now. The hoses on the picture are not easily accessible (without dropping the tranny), as they wrap around the back of the transmission, . So the latest idea is to pump new atf directly into the return line location on the mounting where we pulled the old ATF cooler from; assuming it will circulate through the transmission and then come back out the bottom where the switch unit is. On that note the switch unit is now completely dry of the intermix. Any idea if this implies that the torque converter has also drained? By the time we replace the ATF cooler and button everything up it will be about two weeks of being left open to drain.

[JFP in PA]

Think of the torque converter as being like a squat bottle lying on it side, with the neck of the bottle protruding into the transmission. The fluid level below the neck, nearly ½ the total volume of the rather large diameter converter, is not going to drain by gravity while the trans is in the car. This is why you have to pump oil into the converter, or pull the trans out and turn the converter upside down to fully drain it. Either way, the water contaminated fluid has to come out………

[crwarren11]

That makes sense...thanks for the info!!

****!!