Right on the money (numbers being "lets say").


Furthermore, and this might start a controversy but I have to say the 3.6 motors are less prone to failure than 3.8 (997 generation, revised engines).


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Change the wAterpump and aos at 50k and drive on. Most Porsches have had problems over the years. The 1800 to replace the ims is a lot cheaper than most of the other porsche problems. My memory is lacking but I recall head studs, thermo reactors or something, exploding air boxes, plastic stuff in the metzger bullet proof motors to name a few. Other people have argued this point extensively. I am not enough of a motor head to give specifics but I have read enough that i believe there is lots of truth to this argument.
David

I don't think that's controversial at all - that's pretty much what all UK Porsche magazines reported as well ;-)

They (I think it was 911& Porsche world) had a series on the IMS issues a while back... Pretty much mirrors what was said in this thread. More frequent on M96 (but ironically fixeable pre-emptively), somewhat less frequent on M97 (but not really pre-emptively fixeable for a reasonable $, since case must be split), the issue is more prevalent with S than Base models it seems, also more prevalent on cars that were babied too much vs cars that were driven hard but maintained properly. That's from memory now...

We've been there before in other threads, it comes down to risk aversion. Yes the risk is probably low, but I just *know* I'd be the unlucky one ;-) Given the approx $25K bill (maybe less if using an independent?) for a new motor, now that Porsche is done with courtesy repairs and discounted remanufactured engines, buying a more expensive 09+ makes sense if you are worried about it.

If however you live a charmed life, buy a first gen and cross your fingers. There is also a very small subset of 997.1 which have an M96 engine, but nobody can pinpoint an exact VIN# to determine changeover to M97. I've seen one at a shop, getting an LN IMS, I'd have bought it if it was FS ;-)

The irony is that for a while 996s were in the dump price wise, but now you can fix them (bearing in mind the LN fix also has a limited shelf life of 40K miles if I recall correctly), so they are going up in price. 997.2 are staying high because no IMS at all...
It's now just the 997.1 in no-man's land, until some clever person figures out an IMS fix for them that does not require a case split. I heard something was in the works... haven't heard since...

What about the oil injection from my original post? If you do it preemptively, you don't need to remove the factory bearing. The "fix" in my OP seems like it's ideal for the motors that require that the case be split.

I thought about this briefly when I owned a 2006 997s. At the time, the 911 and porsche world (or whatever article it was) was still open on the internet (It has to my knowledge been closed.) In it, was a tirade of customer reports of IMS failures (at the time- boxster, 996, 2005 997, etc. Also, in it, were the scored cylinders on the 3.8 997S engines. Higher than normal oil consumption, an oily diarrhea from the exhaust, kabamm!!!!

Between the unchangeable IMS and the cylinder scoring (and impending symptoms of oncoming scoring=very high oil consumption) I dumped the car and got eventually got back into an aircooled 911. (The 997s I bought had high miles and burned significant oil- made all the more frustrating by the lack of an honest to goodness dipstick to monitor!)

So- to make 2006-2008 997 3.8 work (for us tinkerers)- make a pressure fed system for the IMS, and address the cylinder scoring. Someone will. It might require a full rebuild with new pistons and IMS mods- but someone will. A good example is the inner plastic seal on the IMS bearing with a pressure fed fix. I guess you "could just punch it into the engine and hope it disappears", but addressing it in a rebuild would be better.

I think the long term issue/question for 2006+ IMS is this: Is the oversized bearing strong enough to a point where the majority of engines need an overall rebuild due to mileage before the enlarged "hail mary" oversized IMS fails? It so, it is a success. If not, I look at it as a $14 bearing that needs an $18,000 rebuild to replace it, assuming the pistons don't scratch the bore first.

Overall, I am optimistic. These cars really are nice. It will happen in time. Until that time. I would replace the broken headstuds on my 78 SC any day over dealing with that stuff. Why? Because I can. As a backyard redneck mechanic, I can. Not only can I replace them, I can replace them cheap. New studs, new seals, new cams, and I am in like flinn. Do I want to? No, but I have a contingency.

I also remember- at the age of 14 or so, reading magazines (panorama? maybe) on failing 944 timing belts. At the time it was more complex than an impending Y2K. In time, I owned several 944's, and replaced those $7 belts with little concern or effort.

So too will a solution for the 2006-2008's (or any waranteed motor replaced with an oversized IMS) come into play! I can't wait! :)

2009s absolutely have an IMS, as do all 911s ever produced since 1965. :cool:

Can't remember what year the 997.2 engine debuted, but I think it was 2009. That engine did in fact delete the intermediate shaft altogether. The cams are driven directly from the crankshaft.

https://www.oregonpca.org/resources/ims-bearing-the-full-story/

Some interesting info in the article. There are some typos, but if you can read around those...
Apparently, the article is a write up from LN Engineering. I guess that means that I trust some of the facts, but then I'm also cynical about someone that sells a product writing an unbiased article.

I stand corrected, did not know this. I'd love to see how they did this in that engine design.

Of course, Mezger and all other 911 engines since the beginning had intermediate shafts.

^Yes, that Oregon PCA arcicle was the exact same one that I read before pulling the trigger on my '11 Caman with the 9A1 engine. Oil consumption has been nil, and it's a fun car.

One weird thing about it is PASM. When hustling it around a corner, you expect to kick the rear end out a bit and expect the apex to be where you know it should be, then PASM kicks in and scoots you about 8 feet to the inside. It's really odd the first few times it happens. It feels like sitting on a chair on linoleum, and having someone scoot the chair to one side.

The fact that LN now recommends replacing their ball bearing IMS retrofits every 75k or 6 years suggests to me that a 5% or even 8% failure rate for the stock bearing is too low of an estimate.

I have a buddy who's "fixed" IMS failed. I suspect we'll see more. As much as I would love to tinker with a cheap boxster, I'm not willing to take the gamble.

Also, we haven't even mentioned all the other ways in which these engines fail.