Get a pre-purchase inspection from Rennsport.
Then you can purchase with confidence.
It WON'T be cheap, but it can save you from a $20K+ mistake.

 

The bore scope procedure is one way to figure out the direct condition of the engine. There are costless indirect ways such as having a full service record for the car. You can have greater confidence if you have the service records or if the owner is willing to allow you to do a bore scope, you can probably just skip it in that case. The 996 is possibly the only 911 to have had a large number of of more than 3 owners in that usually means that the last owners didn't treally care for the car. All of this is to say, we are trying to give you some options to avoid a problem. But as I said here, there are other options. If none of these options are available, you should probably walk.

 

Callas Rennsport is stupid expensive. Dutch Treat is also in Torrance, do good work and are far more reasonably priced.

 

Second these thoughts. If you are hesitating on the PPI because of the cost, you may not have the budget to keep the car running when things go bust.

I put 6k into my 996 right out of the gate to get the engine appropriately restored (was able to bargain the price down appropriately after the PPI identified most of the issues that needed fixing) for a car the owner and I both thought was ready to roll.

 

Here is the thing about cylinder scoring. Scoping through the spark plugs is easier, but it can only confirm that the scoring is really bad. Scoring starts at the bottom of the cylinder and progresses upward. When the piston is all the way down position it will hide any scoring that is beginning. This is why it is much, much better to pay for the pan to be dropped and scope all cylinders from the bottom.

The issue with these engines is the makeup of the cylinder walls and the pistons. Both are aluminum, but the walls are impregnated with silicon and the piston sides have a flash coating of iron. As the piston hits dead bottom it can tilt slightly and the flash coating of iron wears away. Over time enough of the iron is scrubbed off and now you end up with aluminum sliding over aluminum and subsequently galling (bore scoring).

One possible reason this happens is infrequent oil changes and not using good oil. Cold temperatures are thought to be another contributor. If you don't know the history of the car in detail, then yoyu are playing Russian Roulette. Scoring seems to start on the passenger side, but can progress to all cylinders.

If mild scoring is evident you van possibly prolong it with frequent oil changes and I think LN Engineering recommends Driven DT-40 oil with moly. Is this a magic wand? Probably not, but moly will better coat the cylinder walls, so it probably helps. How much is a subjective argument.

If significant scoring is observed it is best to plan a rebuild. You can run it to the ground, but you risk more damage and possibly no chance of rebuild. If you find scoring, LN Engineering seems to be one of the best places for working on engines.

So, this is why people are telling you to get a PPI and in particular, get the pan dropped. I know it isn't cheap, but a catastrophe is orders of magnitude worse.

 

Wow with every post i'm nudged further from a 996. I've had many cars that have had a pretty significant weakest link e60 m5 i had to do a motor replacement(under warranty thank goodness) but now i'm wondering if there is an alternative that'll meet my track/canyon needs. I plan to get into a 2020 gt4 sooner rather than later and was going to get a 996.2 to hang onto as my "classic" because im not paying for a 993 as beautiful as they are

 

Just don't jump on what seems like a good deal without checking it over well.
Any Porsche engine can be expensive to repair/rebuild if it has not been cared for.
An "invasive PPI" is the best way to make certain that you purchase a Porsche with a long life ahead of it.
This is not 996 specific advice either.
997(M96 & M97) & 991(9A1) engines also experience bore scoring.

 

Nah, the 996 is an excellent car. All 20 year old cars from every manufacturer have issues that need to be identified and then prevented with the proper procedures. Everybody on the 996 forum is just trying to give you a list of things to be aware of and how to prevent it.

Just wait until you find out what can and will go wrong with the Gt4 in a few years. Unless you print money from a trusy fund, you will be happy as he'll with the minor issues and costs to keep a 996 running in top form versus the newer Porsche models.

I am, after 22 years of track and street driving on 996.2.

 

I have 2020 GT4 and added a 996.2 Carrera 2 a few months ago. About 3,000 miles in the 996.2 now and I can tell you that it is a fantastic car. Different from and more fun in some ways than the GT4. These are 20 year old cars though so you should do your due diligence and get a PPI like people are suggesting and expect to have spend some money on updates and preventative maintenance. My 996 has an updated IMS bearing already and similar to you I am planning to add coil overs to improve the performance a bit and some preventative mods like the UAOS. The car is already a ton of fun in stock form though. This forum has a ton of information on the common modifications for both performance and reliability. I dream of a Flat 6 or Slakker motor at some point in the future.

I just updated my 15 year old E90 M3 with new rod bearings and valve covers to fix the common issues related to that platform too. Most interesting and higher performance cars have a few things to look out for as you know from the E60 platform haha.

 

We tear down and inspect 3-5 M9X engines a week and have yet to see one where scoping from the bottom would have revealed more information than scoping from the top. And it's near impossible to get to all of the cylinders from the bottom. If scoring is most prevalent on the thrust face then logic has it that it occurs during the combustion phase of the 4 stroke cycle. Meaning that it would start from the top and work downward. Scoping through the plug holes is always our recommended method.

 

Thanks for this info! So many people say otherwise and I'm glad a professional with significant first hand expertise clarified this.

And that report is an excellent educational resource!

 

It depends on your wants and budget. I think the biggest point here is that one's budget needs to be 25% or more beyond the price of the car at a minimum because there are always things that go wrong with any 20-year old car of any make. A GT4 would probably make an excellent car for your wants. You should be able to easily get a CPO warranty with it and drive relatively worry free.

My car was 2 years old when I bought it and came with the CPO. While nothing major happened during the four years of coverage, things like replacing a carbon fiber steering wheel and shifter **** would have set me back a few thousand dollars. Add in the AC control unit and a few other minor issues to correct and it starts adding up.

I encourage you to get a one year PCA membership and start networking with club members (you don't need to own a car for that first year). The cost is cheap and the knowledge you get from other members is priceless, not the least is the chance to buy a car from a club member that has a known history.

Best of luck on whatever you decide.

 

Thanks Slakker. Just printed it off to read. Always looking at it from different points of reference is good.

 

https://rennlist.com/forums/attachme...ing-report.pdf


Also found scoping from the bottom very difficult and not able to get to every cyl completely as good as I'd like. Even using the convoluted method some recommend. All While getting oil dripped in my eye and on camera lens... Good to know bore scoring can be seen from the top no problem, as scoping thru spark plug holes is much much easier, and seems more professional imo.

Best evidence based article I've read on bore score to date.
Thank you Slakker... you're no slacker for sure, awesome article and advice.

 

That is a lengthy and thoughtful report as usual from Baz, but It asks the 96 thousand dollar question , then fails to answer ...

The question ;; what single thing can a finger be pointed at, that would cause bore scoring to start most likely on Bank 2 on the most effected cars?

The answer is quite simple, but not mentioned.....The heat exchanger !!

The heat exchanger is mounted to the top of the engine case and directly above the #6 cylinder ( the one most likely to score first)...and it transfers the heat of the oil under hard operation to the coolant on bank 2 cylinders.....The extra heat thins/lowers the oil viscosity and oil film protection for the cylinders...
...

Keeping the highest quality, robustly viscous oil protection, keeping the cooling system/temperature as low as possible ( in the normal range) and in top shape, will avoid the bore scoring in Lokasil..

Once bore scoring has started, it can't be stopped. The only reasonable repair is to get rid of the Lokasil... As Baz correctly stated, he had trying to replicate the factory process that was invented by KolbenSchmit and the results were disastrous/not long lasting...That process is extremely difficult to recreate, even Porsche had difficulty in the consistency of the process and is why some cars have higher blow-by than others....

If you have bore scoring on Loksail Cylinders, the only solution is to go to something else...Nickasil is the preferred choice at this time ( even though it is an older process )

Also FWIW::: the cylinders can be scoped through the wrist pin access hole for bank 2 ( the one most likely to score) , It is much easier than through the plugs, OR through the Sump.( you don't even have to drain the oil to scope through the wrist pin hole)....but pulling the sump is always a good idea.....you can learn so much about the engine from dropping the sump and having a look..