Automatic trans woes, opinions sought. - 986 Forum - The Community for Porsche Boxster & Cayman Owners

I know nothing about auto’s, the ones I’ve owned have just worked with no thought. With the Boxster the trans was pretty slippy when I first got it. That’s not uncommon. Porsche say it has lifetime fluid, but they are known for getting slippy with old fluid and most people recommend changing it around 45-50K miles. So after draining it, replacing the filter it was much better. When you drain and re-fil you only change approx. 1/3 of the fluid as so much is in the torque convertor. It’s not regular ATF, it’s Porsche specific stuff or Esso LT 71141, or Pentosin ATF-1. Because of that I couldn’t take it to a lube place and get the whole lot flushed out for a 100% change. I changed 1/3 at 77K, did it again at 81K and it’s now around 86K, I have been thinking of changing it again so in theory I’d will have changed 100% of it, but obviously it doesn’t work like that so there would still be around 30% of the old fluid in there. I even checked with the local Porsche dealer and they only do the 1/3 change, not a flush. I will probably change it again this weekend and send a sample with history off to Blackstone for oil analysis. Anyway, a couple of times when the car is cold in the morning, if you manually select 1st rather than putting it in D, it will just rev as if in neutral, until you re-select D instead, but that’s only when cold. This weekend I took my grandson to the Zoo and we parked in a parking structure. By the time we got there it was obviously fully up to temp. It was a super busy day (pet adoption in the main parking lot) so everything was busy with a train of cars winding up through the structure, starting and stopping as people found spaces. After stopping once, I put the trans in 1st by selecting ‘S’ rather than ‘D’ and using the steering wheel buttons to manual change down into first, 2nd being the default starting gear unless you go to WOT, which you don’t do in a crowded parking structure. I then let off the brake to ease forward and the revs rise and nothing happens. It felt like it was starting to roll backwards. I tried more revs, nothing. I tried putting it back into D, nothing. I had to wait, go back into P, then re-select D and we could set off. This happened at least twice. Later when I was on my own at an intersection I selected 1st manually and left hard at WOT, it was an open intersection and when it changed to 2nd at the red line I was still making the turn with a fair amount of lateral G (I was really on it), but instead of a crisp 1-2 **************** the revs flared, I felt a loss of forward momentum then bang, into 2nd and we were off again. Now, I’m guessing the prognosis here is no good and the clutches are wearing. What I need to know is: a) is that the most likely diagnosis b) what’s the expected life span c) will it get progressively worse or will it suddenly quit d) Will I do other damage if I keep driving it e) any magic snake oil additives to slow the progress down f) etc. The transmission itself is a ZF 5HP19FL Also used in the Audi A4, A6 and Passat, the basic 5HP transmission is used in just about all BMW and VAG group vehicles so it’s not uncommon. What I don’t know is how much difference there is between the Boxster version and the A4/A6/Passat transaxle versions if any. As it’s a relatively common trans I doubt that it would be that hard to get rebuilt, but checking online I see prices around $3,800 plus core. That sounds steep to me. Is this something a local trans show can do, or would I be better off looking for a used trans? Used prices seem to run from $1-2K, but honestly if I could get it re-built for that much I’d much rather know I have a rebuilt unit than one with unknown history. While I’ll happily tackle almost anything on a car including going inside FWD manuals, I don’t’ think I want to get involved with the inside of an auto. I’d love to make this thing last until Oct/Nov when I take the car off the road for the winter again. Thoughts, advice, laughter, commiseration? TIA

Any thoughts or opinions? Any auto experts on here?

Probably toast. You can drain and inspect the fluid. If it looks nasty and/or is filled with sparkly stuff, game over. A used AT from a dismantler that has clean fluid will probably be less than 1/2 the cost of a rebuild and will often be a good choice. https://www.pelicanparts.com/techarticles/Boxster_Tech/35-TRANS-Auto_Fluid_Change/35-TRANS-Auto_Fluid_Change.htm

I wouldn’t throw in the towel until you check the fluid level first.

I have a 2003 with a quite fresh and it is a very impressive. I do know changing fluid can help.

I plan on changing the fluid again ASAP, but please remember I've already done it twice so I'm not holding out a lot of hope. I will send a sample to Blackstone labs for analysis too see what they find.

If you do some research online you will see that the 5HP19FL isn't much more complicated internally than a manual trans, and the technical info you would need is downloadable. If you can nurse it through to the fall why not pull it then and give it a try yourself? You probably have worn clutch discs and perhaps plugged or sticking valves and check balls in the valve body due to clutch material contamination. Would be a great winter project!