Tip Gearbox Problems .. ''Slipping'' while driving.

Hi all, More bad news after multiple problems with my 996 , including having to get a full Engine rebuild a few months ago. Pretty soon after getting the car back I noticed the revs rising while attempting to accelerate but no increase in speed. This progressively got worse as the days went by, no flashing red light on the dash, no unusual sounds, and no increase in coolant temperature but a definite slip like a badly worn clutch, as soon as the car warmed up. I'd previously got the box serviced less than 1000 miles ago but decided to start with changing the ATF in the vague hope it would sort things out. The bad news is the fluid that came out of the box was very black and dirty. And new fluid has sorted the problem for a few days but I've noticed the slip beginning again on my way to work this morning. Has anyone else had this problem and solved it? Or any advice please? I have to admit being at my wits end with this car. Nothing but stress and grief , and yet if I could get it running well I know the love will return! I can imagine this fix (like the engine build) isn't going to be cheap, but I want to avoid is throwing parts at it with no results. Thanks all for reading this long, miserable introduction!!

TIP boxes are generally quite reliable hence used ones are fairly cheap. I wouldn't spend on opening the box personally and would swap it for one from a breakers.

As has been said,a second hand gearbox with warranty would be the cheapest way out of this one. Sounds like the friction plates in the drive drums has started to break up or simply wear out. The oil being changed temporarily sorts the issue due to the new oil having better viscosity across the plates

You mention that you changed the transmission fluid. Have you double checked the fluid level is still correct? It can be tricky getting it exactly right as it has to be set with the car perfectly level and at the correct temperature. I assume you've checked for transmission oil leaks? Mine had a leak from a tiny pin hole in one of the welds on the transmission oil cooler a while ago so that might be worth checking. Are there any fault codes in the trans ECU?

The Cayenne centre boxes were failing due to water/condensation getting into the boxes, it stuffed the boxes and knackered the friction plates. A friend had it on his Cayenne and got it replaced under warranty. Your problem sounds similar in that the oil is black instead of cherry red, the same as the Cayenne problem. If it's turning that colour, that quick then it sounds like you might have moisture getting in or a duff seal. Do another fluid and filter change and run it for a month or so and drain it again, if it's black again then I would think you'll have to take the box out. Didn't the cheap Boxster on W/Dealers suffer a similar problem?

Thanks all for the replies so far. I'd trust my mechanic that the oil is at the right level. Re replacement boxes I've not spotted any on eBay. Plenty of Merc boxes though. Just my luck that mine would be the troublesome one. I'd always heard they the most reliable part of a 996 :sad:

did you change the filter ? this could be why the fluid is black having gone thru the filter over a number of days

Hi Ballcock, My car is yr 2000 and I had the same problem as this a few years ago and experienced exactly the same symptoms. I replaced the fluid and had the same outcome as you describe. It is a failure of the torque converter clutch. The slip you describe is the operation of the normal torque converter. This slippage normally occurs in two sets of circumstances 1. when the engine is cold 2. below certain speeds it think between 20 to 25 mph. This is to prevent lumpy drive take up when cold and to allow convertor slippage at low speeds, coming to rest and taking off from standing. The TC clutch engages beyond these conditions so you have solid drive - no slipping. You haven't mentioned it, but I expect the revs drop to tickover on the overrun due to the slippage. The reason the fluid is coming out black as you describe is the excessive amount of slippage in the torque converter is overheating (centre rad will be overworked) and burning the internals creating black deposits and overheated fluid. For me it was engine / gearbox out and the box sent away to a specialist to have a new torque convertor fitted. While out, anything else needed was sorted. That was done about 8 or 9 years ago and still running fine. Well worth doing. Changes are much more snappy, drive very direct and the box is very responsive. It very much sounds like the same thing to me. It is not that uncommon in older auto boxes (though I had only about 50k miles on the clock IIRC) and when I was looking, there was a lot on the net about it when googled.

Yes I had the filter changed at the same time. Thanks Bluebird, doesn't sound cheap! I'll just have to bring it on back to my mechanic again it seems and take the pain. I've just had another look on eBay for ZF 996 boxes but no luck, or maybe I'm just not searching correctly, I don't generally do the eBay thing. At any rate, a second hand box could easily come with the same problems.. I'm living in Ireland so it makes it that much more difficult to return something and to find someone with ZF box experience. Oh well :roll:

Hi That is horrible. I am so sorry to hear about this and feel your pain. So it is actually quite a low miles box. I heard that changing the fluid can precipitate slippage problems because the old fluid contains friction material, and masks the loss of material on the friction plates. Having said that I changed the fluid in my 993 Tip at 187k miles with no issues, and my 130k mile 986 Tip is awaiting its new fluid as I type. I would favour having the old box rebuilt personally unless it a lot more money. Best of luck Berni

Iirc the cost was about £3k for a new Torque Converter to be fitted with a mild refurbishment of the gearbox - a number of new seals and a new valve. There was then the cost of removal and refitting of the engine / box. I don't know how this compares with the cost of a warranted used one. I took the view that to have a near new operating box would be good and that is how it turned out to be. It transformed the driving experience. It was pain at the time, but now i don't think it was too bad as the car ran well with I think a 2 yr warranty. Note this was 8 or 9 years ago.

Personally I would take it out and send it to one of the UK autotrans k specialists< freight will cost you about 60 quid each way for the whole box or 15 quid for the torque converter only!! I am in Dublin too and there is no one I would give it to here!!

Thanks for the sympathy Bernie .. hope you're keeping well. Bluebird, I appreciate all the advice thanks. Pedromix I think I have to agree with you here unfortunately. Too many chancers. I'm going to chat with my indie in the next few days and see where that takes me. In the mean time, it's push bike for me :sad:

ebay boxes https://www.ebay.co.uk/sch/i.html?_...0&_osacat=0&_odkw=996+c2+3.4+tiptronic+a96.00 Sounds to me like you only need a torque converter or your own refurbished...you can get that done here you can get me on 086 2553201 That ZF box is basically fitted to 5HP19FLA Applications Volkswagen Group "” longitudinal engine, transaxle permanent four-wheel drive 1996–2001 Audi A4 (B5) 2.8 V6 quattro 1997–2001 Audi S4 (B5) 2.7 V6 'biturbo' quattro 1997–2003 Audi A4 (B5) and Audi A4 (B6) 1.8 T quattro 1998–2001 Audi A6 (C5) 2.8 V6 quattro 2000–2003 Audi A6 2.7 V6 biturbo quattro 2000–2003 Volkswagen Passat GLS V6 4motion 2.8 V6 2000–2003 Volkswagen Passat GLX V6 4motion 2.8 V6 2004–2005 Volkswagen Passat GLS 4motion 1.8T 2001–2003 Audi allroad quattro 2.7 V6 biturbo 2002–2003 Audi A4 (B6) 3.0 V6 quattro 2002–2003 Audi A6 (C5) 3.0 V6 quattro 2002–2003 Volkswagen Passat 4.0 W8 4motio

Thanks again Pedro, I'll shoot you a text later on if you don't mind?