Duel Row Bearing Consensus ?

[SeanZ4]

I've always crossed my fingers and decided to wait until I needed a clutch job. My car only has 41k mi. so who knows when that'll be???

[Johnny Danger]

Originally Posted by SeanZ4

I've always crossed my fingers and decided to wait until I needed a clutch job. My car only has 41k mi. so who knows when that'll be???

I'm in similar situation wherein my vehicle only has 20k original miles. So, waiting to do the clutch really isn't an option. In any case, I was prepared to do the the IMSB retro-fit immediately. However, the information that arose from this recent Porsche case has me thinking twice now ?

[EssexPorsche]

JD,

Well the recent data certainly influence my decision.

Mine was a single row and i am risk averese ....so retro-fit it was. However if i was sitting on a dual row. I wouldn't touch it unless i was in there anyway. Then for the extra cost i would just swap it out just like a cam belt on any other car.

The odds (assuming the are a correct reflection) are better than a Las Vegas casino win - Happy to take that.

What year is your 'S'?

[Johnny Danger]

Originally Posted by EssexPorsche

JD,

Well the recent data certainly influence my decision.

Mine was a single row and i am risk averese ....so retro-fit it was. However if i was sitting on a dual row. I wouldn't touch it unless i was in there anyway. Then for the extra cost i would just swap it out just like a cam belt on any other car.

The odds (assuming the are a correct reflection) are better than a Las Vegas casino win - Happy to take that.

What year is your 'S'?

I have a 2000 with presumably a dual row.

[EssexPorsche]

Yep, that is my understanding. So despite the low mileage theories, if my car had frequent oil changes and a top drawer history and no sign of any leak down there.....if that was me, i'd leave it alone.

But that really is just my personal take on it: plenty of others will shoot me down.

This is the second such thread i have seen from you buddy, i think its starting to play on your mind or you are perhaps seeking affirmation on what others would do?

Either way - i hope you get the requisite responses that lead you to your decision

[BoxsterSteve]

Originally Posted by Johnny Danger

I have a 2000 with presumably a dual row.

As is mine; but my dual row bearing was at 3rd stage of failure.
Not sorry I had it changed almost immediately.

[drbodzin]

Just replaced my dual row bearing. It was perfect when I removed it. If I had not already bought the new LN bearing I would I would have just left it in. But I feel much better now that I've addressed it.

[southernstar]

Pothole. not saying that replacing a waterpump as a prophylactic is the same as replacing the IMS bearing - clearly the cost for the former is much lower and the consequences of failure much less serious. If the cost was less and there were no other parts in these engines that can fail and lead to similar consequences, that would be one thing. My mechanic's point, I think, is this: where do you stop?

Brad

[southernstar]

jb92563, I think it is dangerous to look at the serial numbers listed in the settlement to conclude that an engine is a double-row: we know that it excludes cars built prior to May 4, 2001 even though cars built prior to that date can have the single-row bearing. It is also dangerous to look at the Porsche engine serial numbers that are listed in the Porsche parts catalogue as that is the CUTOFF date for dual-row bearings: inotherwords, while engines after that will be single-row, ones before that may also be single-row.

While the safest method of determining whether you have a dual or single row is to remove the transmission and inspect the cover/bearing, it kind of defeats the purpose. Once you have gone that far, you may as well replace the bearing.

What Porsche has made clear is that they did not introduce the single-row bearing when it first introduced the 2.7 and 3.2 engines; rather, it was a mid-2000 'upgrade'. AFter its introduction, they continued to use up their supply of dual-row bearings until that supply was exhausted and hence, for a period in the 2000 and 2001 MY, a car could have either. Presumably the LAST engines to have the dual-row bearing would be those listed in Porsche's parts catalogue :

2.7 engine serial number 12851 (last 5 sequential numbers)
3.2 engine serial number 11237 ( ditto)

I am assuming that the May 4th, 2001 cutoff date for inclusion in the settlement coincides with the installation of those engine numbers - ie., after that date ALL engines had single-row bearings. But who knows?

While Porsche has not given the specific date for the INTRODUCTION of the single-row bearing (apart from it being a mid-2000 change), I have opined in the dual versus single-row thread that it was at some point in the 2000 calendar year, rather than the model year: in Europe, where the car is manufactured, 'model years' are largely irrelevant - what we would call a 2000 MY Porsche is a 1999, if built in 1999.

If I am correct, then we can conclude that no engines manufactured in 1998 will have a dual-row bearing (denoted by a Y in the engine serial number prior to the last 5 sequential numbers).

We can also conclude that engines produced in calendar year 1999 ( denoted by a Z) would also have a dual-row, as they were produced prior to the introduction of the single-row in the year 2000.

Engines produced in calendar year 2000 and 2001 may or may not have a dual-row bearing, up until the serial numbers listed above.

The 2000 MY Boxster had a very long production run - while Porsche usually start production of its next MY in late July or August, production started in February of 1999 at the latest (as that is when the first 2.7's and 3.2's were shown at auto shows and made available for testing). Consequently, production of the 2000 MY Porsches continued for about 18 months until late July or August of 2000. Unless the engine was replaced/rebuilt, the only 2000 Boxsters that should have the single-row bearing, therefore, would be ones with engines manufactured in the year 2000. Some engines built in 2000, of course, will stiill have the dual-row bearing, but it is impossible to ascertain which.

The 2001 model year Boxsters, unless they had an engine built in 1999 installed, can have either bearing until the cut-off point for the dual-row in 2001, at the serial numbers listed above.

Again, I would be interested in hearing if anyone with an engine that was produced in 1998 or 1999, that has not been rebuilt, has a single-row bearing. If I am correct and Porsche was referring to an introduction of the sinlge-row during mid-calendar year 2000, rather than model year, there should be none. If they were referring to mid MY, then likely only the earliest engines (1998 production) would be absolutely safe.

Brad

[manolo]

Originally Posted by Johnny Danger

I'm in similar situation wherein my vehicle only has 20k original miles.

As little as you drive that car, would you even notice if the IMSB failed?

[southernstar]

Dave S., that's an excellent price - one that is about $600.00 to $1100.00 less than I have been quoted. Did that include an LN bearing and a complete clutch kit? And JD, with about 2000 miles a year (and I am assuming annual oil changes before putting her back on the road in the spring), I suspect your IMS bearing is looking as good as the rest of the dangermobile!

Brad

[thom4782]

My 2 cents.

I believe that IMS bearings fail when lubrication becomes inadequate due to a leaking flywheel side seal. If my belief is correct, I can only guess that dual row bearings failed less often than single row bearings because the dual row seals were better due to either design, manufacturer or assembly.

In any event, perspective is important. With single row bearings, replacement is like buying insurance against a 1 in 10 possibility of a very costly failure. The so-called insurance premium is roughly $1700 to replace the IMSB. The risk is approximately $5000 to $10,000 to replace a failed engine. Seems like a high premium to me. The probability weighted risk drops to between $500 and $1000 (10% failure probability x $5000 to $10000 engine replacement costs. So in the sterile world of probabilities, its a $1700 premium to avoid a $500 to $1000 loss.

With a double row bearing, the odds of failure improve to 1 in 100. Given the difference in odds, a IMS dual row bearing replacement is an even higher premium to pay compared to the single row bearing situation. This is because the cost to replace the IMSB is the same, but the probability weighted risk drops to 1 % of $50 to $100. Like all cases with insurance, the probability weighted numbers mean little if your engine dies due to an IMSB failure.

So this brings me to my answer to JDs question. I might replace a single row bearing as a preventative maintenance measure. I would only replace a dual row bearing at the time of clutch replacement with one exception. I would replace dual row bearings in cars with low annual miles or infrequent oil changes. These latter conditions allow increase oil contamination and degrades the seals more quickly.

Hope this helps.

[southernstar]

Thom, there is no direct correlation between oil contamination and lower mileage, especially if the car is driven is for more extended runs, rather than the short, in-town, stop and go daliy trips that many higher mileage cars are regularaly subjected to (let face it, that does tend to contaminate the oil). For vehicles that are winter-stored (as Johnny's seems to be), it is of course important to change the oil each spring before putting the car on the road. My car is driven largely as described for about 4-5000 miles a year before winter storage, followed by an oil/filter change each spring when she is put back on the road. I have a magnetic drain plug and also cut open the filter to check for particulate matter. Simply put, the oil that is drained out each spring looks virtually indistinguishable from new.

My BMW X3 is driven year round and not only gets much higher annual mileage, but a higher percentage of its trips are of the stop and go variety. The factory recommends oil changes every 25,000 km (about 15,000 miles) and I can assure you, when it goes that long the oil looks quite dirty in comparison. I would far rather have a lower mileage car that has had its oil changed every 5000 miles at most, than a higher mileage daily driver that has had its oil changed according to Porsche's recommended schedule!

Brad

[Johnny Danger]

Originally Posted by manolo

As little as you drive that car, would you even notice if the IMSB failed?

The windows wouldn't go down right ?

[southernstar]

The windows will, but the hottie in your picture probably wouldn't when she finds herself stranded road-side in a car with a smoking pool of oil beneath it!

Brad

[BrokenLinkage]

JD, even as a clandestine agent, you need to get out more and put some miles on the Dangermobile!
To answer your Q, I believe based on serial number (not visual inspection thus not 100% certain) that I have dual row, and will chance it at my current 87K miles and await the need for a new clutch, or god forbid, some other reason to go there.

[southernstar]

So Sean, for you the 'much less than 1%' hasn't provided some additional comfort in making that decision? To me, the most important aspect of the class-action suit IS the release of numbers concerning the respective failure rates of the dual-row and single-row IMS bearings. Remember, this was obtained from Porsche during the discovery process and the relative reliability of the dual-row IMS bearing was actually used by the plaintiffs in establishing their claim that the single-row bearing was negligently designed, rendering the engines unsuitable for their intended use. Porsche had every reason to inflate those numbers as the difference in failure rate - espeically considering the fact that the dual-row cars were older (and typically would have higher mileage) than the single-row cars, made the case against the single-row bearing a virtual slam-dunk for the plaintiffs.

Put it this way, a reported failure rate of much less than 1% is very low in the circumstances. Heck, it is still very low even if we substantially increase 'much less than 1%' TO 1%, to take into account those who never brought them into a Porsche dealership, or attempted to get compensation after failure. Consider the following:

1. The dual-row bearing cars are now all at least 11 years old; some (manufactured in 1996) are now 17 years old!
2. As a sports car, one would expect that many would have been subject to more 'spirited' driving than the average sedan; indeed, unlike most sedans, a significant percentage would have been used for track-days, autocross etc.
3. The reported rate is not limited by mileage - i.e., it would include cars with 200,000 miles or more! This is not just theory, we know of engines that have gone longer than that without IMSB failure.
4. Again, as the reported failure rate includes all vehicles, it also includes vehicles that were inadequately maintained and where, for example, the oil and filter were not changed regularly.

Considering the above, can anyone really say that the failure rate for the dual-row bearing is excessively high? Certainly, the lawyers for the plaintiff didn't think so; in fact, as mentioned above, they used that low failure rate as evidence of the difference between a well-designed and a negligently designed component.

Can a dual-row bearing fail? Yes, but so can the major engine components of any engine. For some, even this low failure rate will be enough of a concern for them to spend significant money to replace something which is likely not in need of replacement. To make an expensive prophylactic repair on what is now a relatively inexpensive car.

Let me tell you a story about a conversation I had recently with my Porsche factory-trained indy mechanic. I am taking a road trip in my 2000 2.7 this summer and, as I will be travelling to the Canadian east coast - an area that is not exactly overflowing with Porsche dealerships/mechanics, was inquiring about some potential repairs to be done as a prophylactic. In particular, as my car now has about 57,000 miles, I was considering replacing the water pump with a new Porsche facory part. I was already having the serpentine belt replaced and in the process, he had already checked out the pump and found no signs of leaks, or noises or play in the pulley consistent with pump bearing failure. When I asked if I should replace it anyway, in view of reported problems with these units, he said:

Yes, I have replaced a number of failed water pumps on these engines, although generally with higher mileage. Of course, I have also seen transmissions fail - would you like me to replace that too?

Brad

[pothole]

Originally Posted by southernstar

Yes, I have replaced a number of failed water pumps on these engines, although generally with higher mileage. Of course, I have also seen transmissions fail - would you like me to replace that too?

Brad

Heh, very droll. But it somewhat misses the point. The water pump failing can take the engine with it if things really go bad in the wrong way. If a new water pump was $5 fitted, you'd be mad not to change it every 20k miles or so, just to be on the safe side. The fact that the transmission can fail is irrelevant to that. As it is, the water pump costs more than $5 but it's still cheap enough to be worth considering as a part you refresh proactively rather than when it fails. Not every 20 k miles, but somewhere in the 60-100k range depending on how you feel about it.

Another critical point is that there are some parts that when they fail they tend not to take the rest of the car / engine with it. Actually, the transmission is one of these. It won't really cost you more to replace it when it goes than before it goes because it usually won't damage anything else when it dies. With the water pump, a failure could see you overheat the engine and kill that, too. So it makes sense to have a different attitude and consider replacing it before it fails.

There are limits to this. I've done my water pump because DIY it's not expensive. I'm not up to doing my bearing DIY and it's probably 1/3 of the value of the car to get it done, thus a deem it uneconomical. The fact that I have a dual-row bearing makes that an easier call.