Dispeling M96 engine rumors
 

I have heard a few people talking about what is being said on this forum, and how it is really freaking many owners out about their cars. I have been a dealer technician for 30 years, the last 20 of which have been with Porsche. I have torn down several M96 engines after failures, and have built several outside of my primary job as a dealer tech. I'd like to offer my input and share what I've seen to the forum, and in the process dispel some of the rumors that seem to be running rampant.

First, the intermediate shaft. This is NOT a hoax. Most of the engines that we have removed from cars have been caused by failure of the IMS bearing. There are several versions of the bearing that have been used across the production run of these engines. The early cars had a dual row bearing, which has proven to be fairly reliable. Then can the smaller single row bearing. This is where we have seen most of the failures. Starting around 2005 the factory started using a much larger single row bearing, and we have yet to see one of these fail. While I have not yet seen one of the aftermarket bearings, I have to assume that this is a pretty good idea as preventative maintenance, especially if you have a car with the smaller single row bearing. The latest, larger single row bearing cannot be removed without splitting the cases of the engine, since the bearing is actually larger than the hole that you would pull it out through. Replacing this bearing is not a complex job, and could be completed by any competent tech, with barely any additional labor while doing a clutch.

Second, clutches. Whoever says that these cars are due for a clutch by 30K is sorely mistaken. It all depends on the type of use the car gets and how its driven. We've seen plenty of client cars make it to 100k on the original clutch, and we've also seen some go bad by 30k. Whenever doing a clutch, you need to replace the flywheel, so the notion of changing the clutch before it damages the flywheel is a moot point, as you're supposed to replace it anyway. If it's not slipping, keep driving it.

Third, oil. While the factory endorses Mobil 1, there are better oils out there. Mobil 1 is not the product that it once was. At my dealership, we still fill with Mobil 1, but I don't run it in my personal cars.

Fourth, lifters. Whoever says that these cars all need lifters replaced by 60K must be smoking something really good! If this were true, any M96 powered car over 60K would be considerably down on power. I have seen several client's cars dyno'd with varying mileage, and some of the highest mileage cars have put down the most power! Also, keep in mind that if a car had failing lifters, it would be throwing codes. We have put lifters in ONE car, and did so after it started experiencing drivability problems and throwing codes at 110K. Also, I'd like to point out that were there any truth to this, all of the "evil dealers" would be pushing this service as it would bring in considerable revenue on the service side.

Fifth, head cracks. Some of these heads do crack. It is mostly limited to 3.2/ 3.4 heads, but we have also seen a few cracked heads on 2.5 and 2.7 engines. While they could probably be fixed, with potentially questionable reliability, by a head shop, at the dealer, we replace them with new.

Sixth, cylinder wall failures. This has largely become a problem of the past. Most experienced on 2.5 and 3.4 engines, we haven't seen a "D Chunk" failure in quite a while.

Overall, the M96 is a pretty good engine, with a few shortcomings. The IMS being probably the biggest. I see that the aftermarket has made upgraded IMS tensioner blades and oil pump drives, and I guess if you're building a motor the couple hundred dollars this adds could be considered peace of mind, though we haven't seen any of those parts fail at our dealership.

In terms of rebuilding these engines, while not as simple as a small block Chevy, they are nothing more complex than any other German car engine. Yes, you need some special tools and the service manual with some added notes, but its a job that any competent engine builder can perform.

Remember, any modern engine will experience very little wear if taken care of properly. Modern metallurgy, production techniques and tolerances, and modern lubricants have gone a long way toward making engines last well beyond 100K. The M96 is no exception. There is no reason why these engines should not last 200K. The highest mileage engine I have torn down had 120K on the clock, and the cylinder bores showed zero wear, main bearings had virtually undetectable wear, with the rod bearings showing mild wear. The largest area of wear in most new car engines are the heads. The 120K heads were in need of new exhaust valves and a valve job.

To everybody, don't sit home and freak out about your cars, go out and enjoy them the way they were designed!

Thanks for posting and giving your personal feedback Brian. I hope you come back as I'm sure people will have questions for you.

Good post! You have summarized the issues and non-issues fairly and made me a little more comfortable with my car. I have a 2004 2.7, which had an engine failure at 10K, before I bought it. Hopefully the larger bearing was installed at that time.

I've owned over a dozen cars in my 25 years of driving (some really nice, some junkers) - my 02 boxster s is the only one that has had 3 engines in under 80,000 miles.

The M96 is a shamefully poor design in terms of reliability - Porsche should have let Subaru build these engines for them.

One thing that I don't understand is why Porsche changed from a double row to a single row IMS bearing? Seems like they shoud've left well enough alone. The old addage "if it ain't broke don't fix it" comes to mind.

Great post! Thanks for providing your insights based on your experience with these engines.

They probably saved $3.00 per engine on the manufacturing side....wonder what the net of that move is after warranty claims.

Brian:

Thanks for taking the time to unselfishly share your experience and your sobering perspective on these engines.

Hype and hoopla seem to be the norm on the net these days, leading to near hysteria in some cases.

Your post reflecting your 20 years of hands on experience with Porsches on a daily basis is invaluable.

The fact that you fairly evaluate the benefits of the IMS retrofits available speaks volumes about your uncommon lack of $$ driven bias.

Thank you. :cheers:

Regards, Maurice.

I don't think I ever read a post saying the IMS failures are a HOAX. I have read the rate if IMS failures might be exaggerated. And I never read anyone claim the aftermarket bearings are proven more or less reliable than the factories.

The "join date" is at the top right hand corner of all posts.

Regards, Maurice.

While the LN bearing hasn't been proven better than the factory part by a true measure of "field experience" yet, even if it was only marginally better, the fact that you're replacing the original bearing, with X many years across Y many miles of wear on it, with a new part, is still a lot better than doing nothing.

To the OP, what's your take on lightwight flywheels?

"While the LN bearing hasn't been proven better than the factory part by a true measure of "field experience" yet, even if it was only marginally better, the fact that you're replacing the original bearing, with X many years across Y many miles of wear on it, with a new part, is still a lot better than doing nothing. "

Why would I be replacing the IMS bearing? Is it in the maintenance manual as preventative care?

Thanks. Interesting post. A few questions: So MY 2000-2004 have the smaller single row brg?
I assume it's replacement of the earlier single-row brg that is "not a complex job".
Why?
What do you use? Is Castrol Syntec ok in your opinion?

It's not in the maintenance book as preventative care, but perhaps it should be. Seems like lately almost all the engine failures are from the IMS bearing failing. It's just not a good design on Porsche's behalf.

I'd imagine he gets paid by the hour, or salary, with no commission based bonus, so I don't think he cares where we spend our money :)

It's always interesting how receptive people are to news they want to hear.

I'm not saying the OP isn't well meaning, or that he's necessarily incorrect. But rather than dispel any rumors I think he's only added more fodder.

Not that he isn't skilled, but we're talking about 1 tech from 1 dealership, and at least some of what he's said contradicts info and data coming from Flat 6 and LN Eng. and also from a source which long predates F6 and LNE and established info and fixes on some of the nagging issues of the M96 motor back in the late '90's - Autofarm in the UK.

If the Type M96 plague hasn't struck you, you're probably more likely to side with Brian PT.

But, if you're the proud owner of an alloy boat anchor manufactured in Stuttgart, you're likely to remain somewhat more skeptical.

:cheers:

^^^ Trust LB to burst my bubble. ;)

Brian,

can you briefly describe what sort of training a Porsche mechanic receives say right out of tech school and what sort of on the job training/clinics you receive each year?

I concur with these statements..
Using the procedures that LN Engineering and I have developed and continued to enhance many DIY owners have done the IMSR successfully. In fact the only instance we've had was when a 30 year Veteran decided to do the job his way without listening to our directives. Imagine that.

So if some have gone bad by 30k that backs up the statements we've made that at that point wear can be significant, correct? I never made blanket statements about wear limits and service life- I don't do that.

Why do you need to replace the flywheel?

BUT what IF you want to do an IMSR and have the parts accessible to facilitate the procedures and you are at 1/2 life already on the disc and pressure plate, but the flywheel specs out good. Do you bolt it back together half worn out of spend the money and save the labor that would be due imminently?? I know what I'd do and what I've done.

I couldn't concur more..

Thats me. Don't slap me in the face and don't insinuate that my statements aren't true or have been exaggerated. I don't challenge your integrity, don't challenge mine.

And a significant chunk are. Its also not just power, but most every car that we see with low fuel economy also has failed lifters. I recently had a car show up here with 22 of 24 lifters bad, after our work the MPG jumped up 5 MPG, but the power didn't change more than 1HP and 1.5% average torque.

I dyno EVERY car that rolls into our facility, most of them I do for free to grow our data base. I have seen some high mileage engines make huge power as well, one of which had all 24 lifters bad when I disassembled it to be used as a base for a 3.8 big bore!

Nope.. Just like they don't throw codes when the IMS drive sprocket for bank 4-6 slips on the IMS tube by as much as 5-7 degrees retarding the cam timing! The ECu doesn't measure valve lift or events, the last sample point it has is the cam sensor which is upstream of the lifters. The ECU can't tell that the valve events have changed due to lifter degradation, a cam position sensor won't tell that. If a code was ever thrown it would be due to the inefficiency and uneven combustion sampled by the O2 sensors if anything.

The engine we saw that had 22 of 24 lifters bad had no CEL illuminated.

If you tore into more engines and etc you'd see just how many have bad lifters.

No, because that work is too "heavy" for the majority of dealers to carry out.. The last Dealer tech that I had here came from Brumos Porsche.. His first day here he did a lifter job, but didn't know how to do it because in the 5 years he worked there he had NEVER done it!

I concur with the heads that you mentioned cracking the most... I will say that we have created repairs and upgrades for the crack prone areas that can save a head.

De to the variance I have measured with OE combustion chamber volumes to that of the new castings I'd never swap just one new head onto an existing engine. I have seen a variance of 1.5-3.5ccs differential in the castings and thats enough to create combustion imbalance thats significant between the opposing banks of cylinders.

The crack repair is extensive and isn't just welding up the crack. Thats why the head is stronger in the repaired area than it was previously. The first heads we repaired were purposely overheated and we tried to force a failure during the initial testing, those heads are still in service.

I still get a call every now and then with this mode of failure, BUT they are limited to the '99 cars.

Actually you have probably seen an IMS tensioner paddle failure, but it was masked as an IMS bearing failure. The reason for this is the symptoms are exactly the same, damage is the same, the only difference is the chain of events. The IMS issue is so wide spread that lots of Dealerships are blaming any failure of significance on the IMS and some engines aren't being interrogated to verify this..

I recently had an 03 Boxster S that was shipped to us from 2,300 miles away for an engine install. It had been diagnosed improperly as an IMS bearing failure, but the IMS bearing was fine and the chain tensioner paddle was in 3 pieces.

The other MOF thats often misdiagnosed is the bank 4-6 drive sprocket on the IMS slipping and wiping out the entire 4-6 bank of valves due to altered valve timing. I permanently install the IMS drive sprockets with a proprietary process with every engine I build due to how many of these issues I have seen. Some have not wiped out the engines, but this slippage is the reason why most every engine we tear down has retarded cam timing on the 4-6 bank compared to 1-3.

The service manual can get you in trouble fast, especially with cam timing. I built my first one without a manual and without a single Porsche tool. This engine is all about procedure and sequence.

Then why do so few M96s make it to that point?? I agree that there are exceptions, but I rarely get calls from anyone with more than 85K

Actually there are at least 19 reasons why some will not.. Thats how many modes of failure have been documented.

At what axis did you measure the bores? How many positions within the bore did you take your measurements? I'd be willing to bet that by that mileage the #2 and #5 cylinders had experienced taper beyond limits as well as ovality, especially at the mid-bore position.

I concur. I have actually had used bearings PC2 coated and then reused them in test engines with excellent results. I did this when I first started working with these engines, before bearings could be bought easily. As long as the engine has not seen starvation issues it certainly has a god chance of having perfect bearings internally, probably to 200K.

Any head with 120K needs a valve job.. Exhaust valves always get replaced..

Thats what we've been telling people for several years now.

I have made it a primary objective to understand these engines at a level that others have not. We had foresight with these engines and started working with them internally when people told us that we were dumb and were wasting our time because of how cheap a replacement engine was... Needless to say the foresight has been effective.

The things I have stated on my site and on this forum are based on the experience of myself and my team as well as the experience of shops that work with us as our affiliates across the country that see the same things we do.

Before most dealerships had the authorization to tear into the M96 to make repairs we'd already broken and reconstructed most every major component within the engine and we did it all without any assistance from the factory or PCNA.

Respect my experience, knowledge and statements and I'll do the same for you. If you have a problem or disagree with a statement I've made its much better to just come out and say it and direct the heat toward me- trust me, I can take it.

I'd like to hear more of your experiences and I am glad to see you here on the forums, we don't see many techs here.

With that I'll say that its much better to agree to disagree than get into a huge pissing contest between opinions. Pissing contests don't benefit anyone on this forum andI'll warn you now that I am very difficult to argue with.. I gather way too much info, take way too many pictures and have way too many notes to sit on the sidelines without substantiating my information. I go to the ends of the earth to gather this data and retain it just for "challenges" that are sure to come up from time to time.

I have over 1 Tb of data in my corner :-)

Not at all!

And, I'm not trying to play Al Pacino in some Keanu Reeves movie either.

It's just that some guy, with a grand total of some 2 posts initiates a thread labled "Dispeling (sp) M96 engine rumors ", adds that he's a Porsche Tech and people (well 13 out of 14 anyway) are ready to follow him like he's the Pied Piper of 986ville!

I'm not saying he's wrong, but as he himself points out, he attempts to "dispel some of the rumors that seem to be running rampant".

At least to my mind, he was not successful.

IMS isn't the only issue here. What about RMS, faulty ignition switches, weak waterpumps, window regulators, seat belt latches, plastic rear windows, convertible top push rods, and on and on? The OP didn't address a single one of these.

Granted, IMS failures may well be the 'pancreatic cancer' of these cars, especially the mid-gen cars (that's not exactly a revelation). But what comfort is that to those who suffer merely from the 'prostate' or 'melanomic' varieties?

:cheers: