Silver_TT

Simpler is always better (all else equal) 🙂 Thank you for your attention to correct information and for posting pictures of the new and old parts.

I have spent time in Salzburg -- I went to the Christmas markets there the Christmas before last with my wife and kids. My wife has family outside of Munich on the Chiemsee so I rent a car and drive to places like Austria because it is so close. Pretty cool how that Christmas market is in a shopping area just built into the side of a rock mountain. I hope the fluid change will fix it for you. Definitely try that first for sure. If this is only happening when it's cold, and never when hot, then it may be the fluid. Generally bad synchros would be bad no matter what the weather. The detent is cheap and easy to install. If you end up needing a gearbox repair let me know and I can ask my wife to ask her family. Her cousin has a 911 TT and GT3 and is an engineer so he might have some idea, he obviously likes the cars. Given where you are I'm sure there is someone qualified to work on that gearbox if necessary but you want to do your homework first and be sure they are legit and can handle it. Things can really go south if you don't get someone who knows 100% they are doing on this job. Please keep us posted and my best wishes to you

In my almost 20 years of exposure to the Porsche platform it's my opinion that people inflict more damage on themselves than it is Porsche's fault for being expensive to maintain. In my case for example, that was a $4500 bill (and that's not counting my indy's bill to take the gearbox out and back in of the car) that never had to happen. But the person I bought the car from, I learned after buying the car, is a spoiled little brat who doesn't know anything about taking care of his belongings. He is just one example but many of the things I have read out there on the internet and otherwise about people's advice with respect to taking care of their cars is, frankly, quite shocking. it doesn't really happen here because the moderators and admins are educated and this is a moderated forum. But outside of this little bubble we are in here it is rampant to say the very least. Also by way of clarification in case anyone wants to know why the 4th gear and 3/4 shift sleeve are discounted in my bill, this is because Stan had a "used" or otherwise not brand new part that he assured me was in perfect condition and just as good as new else I would have paid for a new one. I wouldn't trust most people saying that but if you have a 2 minute conversation with Stan, you can see this is a person who is dialed in on these gearboxes to say the very least. If anyone did end up needing service on their gearbox I would be extremely selective about who I choose to work on it and I definitely would not consider any local shops like transmissions shops. These gearboxes require specialized knowledge to even open them up safely.

Agree. But that $4,500 was cheap. Before some smart person alerted me to the existence of GBox (gee whiz, who could that be) my option from Porsche was a new gearbox 😬

Sorry just saw you're in Germany (my wife is German, from Berlin, I spend several months a year there when it's not COVID). I don't want to alarm you but reading your post closer sounds very similar to what happened with my car (mine did it hot or cold though). I would try the detent first (if the fluid change doesn't fix it), which is what I did (but in my case neither worked) Here was my bill:

Yikes be careful. The previous owner of my 996 TT put redline in the Getrag gearbox (and didn't tell me and removed it from the "complete" service records I got with the car.... shady, shady, shady world of used high end car sales). It trashed some of the synchros and cost a lot to fix. Passed a PPI and all that before I bought it.........I did my homework, dotted my "i's" crossed my "t's" and still got burned That said I do recommend Stan and GBox out of Boulder, CO, which is the shop that fixed it. They did an outstanding job and no one knows these gearboxes better than Stan.

The difference can be something so simple as a part supersession. They don't tell you what changed -- it would be great if they did; it could be a supplier change, an actual upgrade or change of some aspect of the part itself, etc. The safest thing to do is always to order OE parts for your car using your VIN like you did above and don't assume.

Not familiar with Foxwell, most people here are using Durametric. Someone already mentioned previously, ROW 3.4Ls only have one sensor located on bank 1-3. The cam position sensor is important for a number of reasons but plays a critical role in giving the ECU the information it needs to advance/retard the timing. USA cars have a number of differences often related to emissions (eg. pre and post cat O2's in the USA, etc).

Another vote for Driven. In my engine, which is very similar to the Macan's small displacement turbo-charged engine, I'm running DI40. Also all I use now after spending countless hours reading academic and industry research on tribology, LSPI, etc. If you go over to LN Engineering's website, Charles actually purchased an LS-1 engine and is running it non-stop until destruction -- these people are my kind of testers.

On the aging I def agree it's best to test -- I was asking out of selfish curiosity because I dumped my coolant over the summer and it was probably about 6 years old (obviously I will never be able to test it now that it's gone). I'm not worried or anything. That's a really good point about the acid and soft/thin metals. My car has a turbo so the intercooler could corrode as well. I've been reading your posts for years and still I often learn something new after reading them. Awesome that you can do all this magic with just a few inexpensive tools. Thanks again for all the info, I've learned a lot

It's interesting that Porsche recommends mixing their OE coolant. I know they are under the VW umbrella technically now and I just looked and my 2.0T coolant came premixed 50/50. It's more expensive to buy this OE coolant but, as I mentioned, after being burned for $5K on a gearbox due to someone else's mistake it has made me think twice about trying to cut any corners whatsoever (which is something I never did much of in the first place but I know some people think I'm crazy about OE fluids/parts but once bitten twice shy). Just curious at what age/mileage did you normally see the coolant start to break down on the aging curve? I was also wondering what adverse effects acidic pH has on high alloy castings -- does it do other damage aside from breaking down the glycol in the coolant itself? Thank you for all this information. I hope other people read this and benefit from it.

Both the pH and refractometer -- I'm glad I asked, thank you for correcting me. Interesting how you put it, I never thought of coolant like oil but it makes sense. I did not know that the newer "lifetime" coolant wasn't really lifetime but since you are comparing it to oil it then goes without saying. Of course people talk about oil all the time but you don't really ever run across too many conversations about coolant (despite the fact that it's also critically important). What specific kind of water are you using with the pre mix (anything beside distilled water)? Also is there a specific brand or type of antifreeze you prefer? When I just did my overhaul over the summer part of the work involved dumping and putting in new coolant (at least I know lifetime coolant means if you're dumping it to do work put in fresh fluid when you're done) and I just went with the OE coolant which I would have to go back and look but I'm pretty sure came pre-mixed. To that end I have been overly paranoid about any fluids in my vehicles in general always using OE fluids for everything after the situation with my 996TT Getrag gearbox which was trashed by the previous owner using an aftermarket oil. Listening to Stan (at GBox) talk about that was something that stuck with me.

Great explanation, I understand now. One thing I wanted to ask you is that many coolants come premixed these days with the water so you just add it as-is, no need to mix with water in a specified ratio. So you know when you put it in the ratio is spot on. What is causing that ratio not to stay stable over time? Also just to be sure I understand, the pH test is an alternative to the refractometer, correct? In other words you did either or, not both. Not sure if it's true but I read that using the pH strips is what you use for propylene glycol (check for pH under 7 indicating acidic) and for ethylene glycol coolants you test with a hydrometer. If everything I stated is correct it seems the simplest and best to just use the refractometer only and just know what kind of coolant you have (it's listed on the back of the coolant). Thanks for all this information.

I just looked up the coolant refractometer. I had never seen that before. Looks like it can test maple syrup sugar content too, wild (don't worry, I won't use the same device 😛). The following picture is what I believe you see. What value range are you checking for? Also should I think of measuring the pH level an alternative to using a refractometer? What pH level would be equivalent to the specified ethylene or propylene glycol level?

Thank you. Didn't mean to drive this thread off topic but I just had to ask because some of your posts have caused me to think about things in a way that have subsequently allowed me to make important discoveries. I am effectively mirroring what you your shop does. Coolant freeze point pH is a good one, I'll add that to my list. Thanks

Yes, I definitely agree. If it's a serious vacuum leak on my vehicle it usually results in a CEL for oil pressure and/or the AFR being too lean. You have mentioned before that for every car that came through your shop you did this vacuum test and I know you also load tested batteries (which is a common practice among good shops, at least the ones I know). Is there anything else you had on your "list" each time a car rolled through aside from these two things?

Awesome, thank you. I have read several "reviews" that test this exact digital manometer you have against both a professional field unit as well as the U-type liquid unit and they all said it gives results that are both very accurate and precise. I'm going to buy another oil cap for my car and do this for fun one day when I'm bored. The idea would be to also do it every 6 months/5K miles/whatever going forward to see how the unit performs over time. Obviously you want to be sure you don't have any vacuum leaks that would "pollute" the reading -- in my case, don't think I have any as I have looked the engine over obsessively to check for stuff like this. That is really too bad about the improved AOS. Seems like there's enough liability in just rebuilding an engine with OE parts -- he talks about it in that link, brand new installed factory AOS unit worst case is it goes out on a customer car that goes back home across the country and then dies resulting in Jake having to pay a local shop out of pocket to fix the faulty AOS and sometimes they try to take his lunch with it (to this end you can see why a Flat6 rebuild isn't cheap compared to some of the other people out there who frankly just don't stand by their product in the same kind of way). Obviously the environment is incredibly important but it's just too bad in this particular case that the laws aren't written better in this regard for innovation. Thanks for the good information, you have so much of it.

Hey JPF, I wanted to know more about how you tested the cars that passed through your shop. Did you use a digital manometer? I have never used one before but wanted to try it. It looks like you just need to hook it up to the vacuum line somewhere (can use oil tube for example if you can seal the connection) to have to be part of the pressure system for the crankcase. When I look at images of the device it looks like it has two hose inputs as opposed to a traditional analog vacuum pressure gauge which only has one hose tube. Would you put both of those hose lines into the sealed oil cap/tube? Just curious how exactly you did this because I understand how it works in principle. After connecting it I'm assuming just start the engine and let it reach operating temp. I was going to try this on my car at some point just to test my brand new AOS for fun. Edit: I think I answered most of my own questions by finding a RennList post on this: Air Oil Separator AOS Question - Page 3 - Rennlist - Porsche Discussion Forums RENNLIST.COM 996 Forum - Air Oil Separator AOS Question - Hello all. I think I'm going to have to replace the AOS. The bummer is that it was replaced 3 years ago at around 70K miles. The car now has 103K miles on it. It is a 2002 C4 Cab. There is a lot of vacuum on the oil fill tube when the car is... The only thing I can't tell from the picture is what the the second hose input (circled in red) connected to, if anything? Upon further review it seems this manometer I showed specifically has dual pressure connection inputs -- but it isn't required, just a feature. Some manometers just have one connection, for example, from what I can see. Edit 2: Did Jake ever release the improved AOS he talks about in the RennList link back in 2017? Just curious as he indicates it could be any day now 3+ years ago. I did not see it on his website, maybe it's on LN? Curious what specifically he did other than bench test them out of the box -- shocking quality control to have them failing out of the box (Jake mentions, for example, glaring errors such as the factory forgot to glue the seams together).

This is a 10+ year old post so part numbers listed may very likely have been superseded. I would call Sunset, give them your VIN, and order the latest part from them. This is a fantastic thread.....the information given by Izzy is very helpful.

I just looked at what you have -- that is a nice setup. Yes, you are correct it would still slosh outside the baffle. I guess they are not mutually exclusive but I agree with you that is pretty funny about buying a +2qt only to underfill, it sounds funny at face value at least. Bilt Racing Service BRS 2QT Deep Sump Oil Pan Kit MY97-08 M96/M97 inc. X51-Style Baffle LNENGINEERING.COM <p>The Bilt Racing 2 QT Deep Sump Kit provides similar oil pressure drop protection as an Accusump kit, but takes oil control to a whole new level. We've had Pro Racing teams use our kit to solve their oil starvation and aeration problems completely, when

One question I had in the revised drawings is on the hard turn I see a lot of the oil being forced over. In my car there is a baffle in the sump which keeps the oil from doing this. Does the M96 have this as well (I know xmac said he's running the LN deep sump)?

Thanks. Yes from what I saw taking apart the AOS the diaphragm with the tension from the spring is what throttles the vacuum to the specified level. In the event of a torn/cracked diaphragm I have seen some people don't replace the part and only replace the diaphragm/spring. While much cheaper, I personally think this is not a very good idea since I have seen problems caused by this where the diaphragm was a different material or the spring had a different size or tension, which can cause things not to work correctly. There are several reasons actually but one of the reasons I replaced this part preemptively in my car is because when a AOS fails it can cause a lot of excess pressure to build up in the case which can damage the rear main seal (which is a PITA to get at). I have never seen that cited on the M96 but in theory I would think a bad AOS on a M96 could blow out a RMS (or any other seal for that matter) too. Nice diagram by xmac. That's a good high-level visual of how it works. Thanks for doing that.

I agree with this and never gave this much thought until I started to research it in depth a few weeks ago. In the AOS I replaced last week in a different car I wasn't getting any CEL's and the car drove just fine. But when I pulled the intake hose a bunch of oil streamed out everywhere. When I inspected the AOS I could see it was no longer working 100% and allowing oil to bleed into the intake. I will always replace my AOS every 40 or 50K miles going forward even if there is nothing wrong with it. Also meant to say in my last post my 996 4S used to blow some oil smoke on the track, especially after the hardest laps. As far as the throttling the intake vacuum down is this concept where the "breather" term comes from?

Very interesting post, thanks for starting this discussion. I just replaced the AOS on one of my cars last week so this topic is of interest to me at the moment. It is definitely true that the AOS helps collect and reburn blow-by, which helps reduce costly emissions and increase efficiency. When the AOS fails or starts to fail the vacuum pressure increases massively which can cause oil to actually get sucked into the intake and raises the possibility that you could destroy your engine by way of hydrolocking it with oil:

Yes, definitely agree with JFP. Just did a similar job on my car about a week or so ago and I was puzzled when I pulled off the intake and quite a bit of oil dumped out (much more than just a film). But upon close dissection/inspection of the AOS unit I could see it was on its way out and allowing much more oil to "bleed" into the intake than it should have been. I wasn't losing any oil between 5K changes as of my last change but I suspect if I would have let it go longer it would have started to burn some oil if the car didn't CEL first alerting me to the issue (I changed the AOS as a preemptive precautionary measure after realizing it was 80K+ miles/7+ yrs old). Congrats on your purchase!