M96 vs M97

[berty987]

There was some data collection done over on Boxa net regarding IMS failures. Ok it wasnt a full listing of all the IMS failures recorded , but of the occasions identified it seemed to pan out to a 30 to 40K figure. I agree that this isn't a basis for a statement that all IMS failures occur before 40 k is reached , it just points to a probability that its higher. Until I see some catalogued evidence of an even spread of IMs failures in hgher mileage engines I will continue to beleive that the IMS failures are not random but caused by external influences such as mileage , oil change interval and driving behaviour . Bearings should fail randomly and the fact its not deemed a servicable part suggests it should in most cases outlive the rest of the engine. A grouping of failures at 30 - 40k miles suggests a special cause failure rather than the normal random causes.

[fpb111]

Food for thought: with 15k mi recommended oil changes 30-40kmiles is right around the 2nd oil change, more sludge? Maybe sludge protection is one reason Porsche put a "sealed" bearing in an oil bath?

This was an exchange on Pelican Parts Forums-

I took my 1999 c2 in for a 45000 miles service to the dealer about a week ago. Got it back the next day and it felt like a brand new car. A couple of days ago tried to start it but made an ugly sound and went dead instead. Got it towed to the dealership and few hours later I get a call from the service guy telling me that the engine is blown and it needs to be replaced.

Does it make any sense to you guys? Isn't the service supposed to detect these kinds of problems? I’ve bought this brand car new and I’ve always kept up the maintenance and I only drove 150 miles since the last service. If I decide to go ahead with the work needed how do I know that it wouldn’t happen again next week?

Any advice is appreciated…

Thanks,

Dan

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Unfortunately this is not uncommon. An intermediate shaft bearing can let go with little warning trashing the engine. There is also a condition with some engines cylinders that results in a "D" chunk failure.

See December Excellence for a good explanation of these two problems. Also see the buyers guide on the Hartech web site section 4 has much data and pictures.

http://www.hartech.org/docs/buyers%2...20part%204.pdf

Many of us read and quote Excellence Magazine. In this month’s issue, May 2009, Bruce Anderson’s technical answer column, addressing a question about the design of the M96 engine, contains the following information.

“When the Boxster and 996 were relatively new cars and the M96’s problems were not yet understood, rumors suggested that up to 50% of the cars were going to experience failure. Porsche addressed the problems and, today, I am hearing the number of cars that have had or will have a problem is closer to 20%, or one in five.”

It is good to see that “Porsche has addressed the problems”. So those who have a Boxster/Cayman/996/997 with an M type engine know that you have an 80% chance of not suffering a catastrophic engine problem.

Make sure that PCNA has your current address and vin so you won’t miss the updated component install recall… NOT

Maybe we should start a club with a cloisonné car badge and “T” shirts? “The 20% Club”

FPB111

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A tremendous amount of M96 engines have seemed to fail just after Porsche service!! I have 1/2 dozen emails that have the exact same words that your post does and thats amazing!

Sorry to hear about the failure, but I'd like to get more info from you about it to help build my data base..If you want to avoid all of this in the future, feel free to contact me :-)

Jake Raby

President, Raby Enterprises Inc

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Blown engine after Dealer Service

Mr. Raby,

The first paragraph in your reply to 20n78x8 above;

“A tremendous amount of M96 engines have seemed to fail just after Porsche service!! I have 1/2 dozen emails that have the exact same words that your post does and thats amazing!”

Made me think about how some dealers might service an oil change.

For instance

I have a Mercedes that gets free dealer oil changes every 10K miles. I change it at 5k intervals so every other change is free. My point is that the dealer has not pulled the drain plug on this car, the glyptol I put on the plug is never broken. They must suck the oil out through the dip-stick port. This leaves some “sludge” in the pan.

If a Porsche dealer were to do this with the “M” type engine couldn’t that also leave sludge in the pan? If that sludge were stirred up when the new oil is added it could migrate to the low mounted IMS bearing and cause failures. Are most of the above mentioned emails IMS failures?

FPB111

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Never really thought about this, because I can't fathom doing an oil change without purging the oil via the drain plug!! I can see where it could contribute to a failure, but it could never be proven.

even the drain plugs on the M96 are cheesy, they need to be replaced after 5-6 oil changes because they are internally stripped of their hex used to remove them, so thats more reason to purge the oil via the method you mention..

That makes our billet aluminum, magnetic drain plug even more of a benefit to the engine, IF the dealer changes the oil with this method! (and it won't strip out!)

Jake Raby

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Mercedes and BMW have been sucking the oil out through the dipstick hole since the 90s.

It's why on most models, the the oil filters are on top of the engine.

For an oil service, the vehicle does not need to be lifted on a hoist.

It comes down to the same scenario...you are only meant to keep the vehicle until the warranty expires, then you buy a new one.

Gerber Motorsport Inc. 206-352-6911

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I don't know about BMW but that may be why Mercedes changed thier oil spec around 2002 from petrol based to synthetic oil due to sludge formation. TSB S-B-18.00/16a.

I would think that even a very slight amount of sludge in an M type engine would be more critical due to the sensitive IMS bearing immersion in the sump oil.

FPB111

Edited March 19, 2009 by fpb111

[355bhp]

Hey, I just noticed in my MY '05 "911 Carrera" owner's manual, that the Engine Data page states that the "911 Carrera" has an M96/05 engine, whereas the "911 Carrera S" has an M97/01 engine. Are there any internal differences from the M96 besides the .23 liter displacement increase? The build date of my car was 10/29/04.

[986Shaft]

Deleted by departing user.

Edited June 24, 2009 by 986Shaft