When you see real-world problems of intake valve gunk on a 9A1 engine please post some pics.

Re the 970 engine... different engine, different geometry.

 

I was able to find some posts which had specific engine (not VIN) numbers for different car models showing when exactly switch from dual-row bearing in IMS to single-row bearing. Essentially you should be pretty much safe if you car was made after 06/2006.
New single-row IMS bearing does not guarantee issue was 'fixed'. Only 997.2 new DFI engine guarantees that.

Also other reason to prefer cars made after 06/06 is because they got updated version of electronics hardware.

 

A build date of 6/06 is actually quite late in MY06, I think the MY07 cars may have started being built as early as 7/06. Most things I have read state that all MY06 cars have an improved IMS bearing an even late model MY05s. Perhaps a further IMS refinement was made starting around 6/06?

Would be nice if Tony could weigh in on this.

 

Several comments here:

1. First, the 05' 996 3.6l and the 05' 997 3.6l are the exactly same engine from throttle body to exhaust manifold. The short block is 100% the same. The heads, cams and intake are 100% the same. The only differences are some revision to the accessory routing, the exhaust after the manifolds, the intake airbox and the DME programming. If you change the accessory drive and 2 sensors over, you can directly put in and run a 997.1 3.6l in a 996.2 with the 996 wiring harness.
2. If you get a replacement 996 engine from Porsche, it comes with the improved/larger IMS, RMS, oiling system, etc. The larger IMS was not in the 05' engines, it didn't come along until 06'.
3. All Porsche replacement engines get all the latest updates through the latest production year. With the 9A1 engines out, we probably won't see much for updates on the M96/M97.
3. Every year Porsche made improvements to the engines and the cars. If you want the best one, you buy the newest one.

Last (plug here), I am selling my 02' 996 Carrera that has a brand new (2009 build) 3.6l X51 engine with a factory warranty through July 2011. It has all the latest improvement that include the larger intermediate shaft and bearing, improved IMS and improved oil system. By this thread, it is better than anything that preceeded it; which includes a 07-08' M97.

 

One of the big questions for me - and why I'm anxious to hear Tony's response - is whether the final redesign of the IMS/IMS bearing really fixed the problem. If not, one could make an argument that an 05 997 would be a better choice as a LN Enginnering IMS bearing can be installed preemptively. It's my understanding that the LN bearing cannot be fitted to the later engines.

 

Interesting quote, "The car has been out 18 mo. and minimal issues have arisen". So 18 mo and we're ready to call it a success?

We are years into the M97 and people are still debating the reliability issue, I don't think we are all ready to cast our ballot on the new motor just yet. Also, can we really say carbon build up is a non-issue for the Pcar motors? I've read that it is an inherent flaw with DI motors that VW and Audi owners have been dealing with for some time now. Further, it is an issue also being addressed by Toyota, Ford, etc. That being said, I think DI is the wave of the future (more efficient, better gas mileage) and I'd take a 2010 in a heartbeat...

I've done a decent amount of research on the whole M96/M97 issue. My understanding is that ALL 2006 year cars received the beefier single-row IMS bearing upgrade and that SOME LATER 2005 cars may have the upgrade as well. As someone else stated, you have to look at your engine code to determine whether or not your 2005 was part of the lucky group or not. I've also received direct advice from a Porsche mechanic who says he has seen MANY more 2005 cars come in for problems vs. 2006 and later. I can't statistically validate his argument, but I'm going to take his word for it.

I also agree with what someone else stated. If you are that concerned with the IMS, why pay $2500 for an extended warranty? Just buy the IMS upgrade (I think it's from Jake Raby???) and call it a day.

As far as Tony's advice goes, I've called Callas Rennsport several times with general questions, and they have ALWAYS been very accomodating. A while back, Tony even emailed me an extensive list of issues for M96/M97 variants. It's nice to have a Pcar resource who is genuinely out there to help and inform.

 

buy ANY cpo of your choice, and drive the **** out of it. if it fails porsche will fix it...100k miles!

 

That's the most astonishing argument against DFI I've ever heard... No, actually, I think it's the only argument against DFI that I've heard unless you listen to beancounters. (Who don't count.) In fact, I think it's the first time I've heard anyone worry about the temperature of intake valves since we constantly cool them with the incoming charge, with or without th
at charge being cooled by the injection of fuel. Intakes live in a New England Winter compared to the Sahara where exhaust valves live.

Of course, I intentionally bought a 2009 to get the 9A1 engine so what do I know?

Gary

 

Only way you will know for sure is to buy a new engine, put it in a car and see. I haven't had a single problem during the 6K miles I have on my 2009 build 3.6l X51 engine. In fact, the oil pressure is surprising how much higher it is. It idles as 2 bars fully warm, is at 3.5 bars by 2000 rpms and is at 5 bars by 3000 rpms. My original engine was at 1.3 bars at idle and didn't hit peak of 4.5 bars until above 4000 rpms. The new X51 doesn't even use any oil versus my old 3.6l that would consume about a quart every 3-4000 miles. Even my new GT3 doesn't get 2 bars of oil pressure at idle.

 

“Thanks Tony. A few questions from a would-be 997S purchaser (as my DD).”

“1. I've heard conflicting information as to when Porsche switched to the M97 engine. Do all 2006 997 cars have the M97 engine? If not, is there a way to externally identify the updated engine?”

I think you are fairly safe to assume that all 2006-2008 997's have the M97 engine but I try to never state absolutes when it comes to anything Porsche manufacturing related. As for an easy external identification while the engine is still installed, you can look on the driver’s side of the engine, just above the engine oil pan to locate the engine number. This number will start with either an M96 or M97 prefix.

“2. Have you seen engine failures in the M97 engines? I know they are still relatively new, but it concerns me somewhat that Porsche chose to redesign the engine just 2 years after they supposedly "fixed" the problem in 2006. “

As most of you already know, I am not a big fan of the M96 and M97 engines but I am sincerely trying to like them. Yes, I have seen light scattered pattern failures of the M97 engines but mostly due to casting and machining issues. Having said that, I do not think that the M97 engine is the best engine Porsche has built, LOL... I have more trust in the new MA101 and MA102 engines at this point. See answer to #4.

“3. Are there any other mode of failures to watch out for with the M97?”

Well, as for the M97 engine, I feel that the days of D-Chunking, floating crankshaft cradles and RMS issues are (for the most part) behind us but I am not so sure about the IMS bearings yet. More frequent oil changes and the utilization of a better engine lubricant will be play a substantial part. See answer to #4

“4. In what other areas were the M97 engine improved? I've read about issues with timing chain rails, intermix issues (head cracks) and rod issues with the M96. Were these areas improved on the M97?”

This is where additional time would be needed on my part to explain my answer thoroughly but I can state this for now. I have always felt that a lot (not all) of the M96 engine issues were due to a lack of quality control and low cost manufacturing issues. I truly like the concept and feel that the M96 was a uniquely revolutionary design. A lot of these issues were caused in the “aftersales” arena (dealerships and agencies) such as technicians not properly torquing down the camshaft cover/s hence some of the cracked cylinder head/s. Please note: I personally feel that the long oil change intervals of 15-20k miles and lack of high pressure additives (Zn and P) in the lubricants are and will continue to be the blame for a lot of the engine failures (IMS bearings, worn chain rails, broken timing chains, rod bearing issues, etcetera). I feel that if the engine oil in all the M96-M97 engines was changed every 5k miles or every 6 months, it would have drastically reduced the number of failures

I am spent so I hope this all makes sense.

Tony Callas

 

First, I don't think you can directly associate this to engine failures. Why? There are a lot of failures on engines that get oil changes every 3K miles and those who run additives or deviate from the Porsche recommended 0W40 oil. To be honest, I don't know anyone who waits for even 10K miles to do an oil change. Let's face it, this is a zero clearance engine. Anything that breaks on a moving part could take out the engine. For one, just look at the spec Boxsters. You have people running 97' engines that have never been touched that beat on theirs almost every weekend for over 2 years and have never had a problem and others who built a blueprinted motors measuring every part to detail and blow a motor in 2 races. It certainly is not the oil or the oil change interval in this case.

 

Sarcasm here is not really asked for. Earlier versions of DFI engines did suffer from carbon build-up on valves and excessive carbon build-up may damage valve.

It is also true that since than a lot of ways were invented to minimize that carbon build-up so I would say the only way to know for sure how new 997.2 engines will stay on this issue is to let some time to pass.

 

The M97 is simply a glorified M96, it is NOT an entirely redesigned engine as many believe.

Over time Porsche did address some of the weaker areas of the M96 with the development of the M97, but we are now starting to see and hear from M97 owners with the historic failures of the M96. This is due to the fact that the first generation of M97 equipped vehicles are coming out of warranty and are beginning to be maintained by Owners or Indy shops.

Only time will tell.

Unfortunatey with the M97 the IMS bearing is NOT possible to replace with the engine assembled as the larger OD of the /97 bearing is larger than the ID of the case bore. If you have a bearing that has imminent failure, the entire engine is compromised.

 

Thanks for your response, Jake. So you can retrofit an M96 but not an M97? By the way, I think your website and detailed information regarding the M96/M97 is a really good read for any potential 996/997 owner who hears of all these concerns about the car.

 

Jake, Thanks for posting and clarifying this information. So, have you seen any (or should I say many) M97 IMS bearing failures? Tony