mklein9

So in the end, the original title of this thread, "Shavings from old failed IMS (??) now showing up?", may actually have been correct. Old shavings remained in the engine after the original IMSB was replaced at 28k and were circulated through the oil filter bypass. By 41k when the engine was torn down, due to ineffective filtering the particles had precipitated wear in the new IMSB's steel races, the main and rod bearings, lifters, etc. Given the ineffective filtering the damage was progressing rapidly. No other sources of wear were found in engine teardown. New IMSB and rod and main bearings were on the verge of failure; lifters wearing rapidly as well.

What could have prevented this?

1) Thorough cleanout of all metal debris from the old IMSB (or, preferably, having replaced IMSB before any damage). I.e. following LNE's procedures and not just throwing a bearing in. Given enough debris, this may or may not have been possible.

2) Full flow filter or regular checking and replacement of the oil filter housing ($30) in addition to the OEM filter

Like some in this thread, I was initially skeptical that Jake/Charles were correct in their preliminary comments because of the often-mentioned sample bias they're working under as well as what their business is. In the end, they were spot on.

dgjks6

All I know is that this thread cost me $9000.

Weissach

After reading threads like these, its no reason that 996's keep dropping in value. And by the way, 99% of buyers find their used cars online. They will also find rennlist on the first page of Google, and read all about its fantastic engine. No bueno..

mklein9

That's seriously bad. Care to expand?

Between the two of us then we might be about even.

Flat6 Innovations

Thats all that matters.

This thread is a perfect chronological illustration of what occurs when procedures are carried out without any sense of awareness about after effects. This is because people carrying these things out do not understand the dynamics of the engine, how it works, or how the sub-systems operate.

Here's Mike's Rear Main Seal (RMS). This is exactly as it was when the engine was pulled from the car and I was standing there when the flywheel was pulled off. I literally used my fingers to remove this seal from the crankcase bore, the only thing keeping it in the engine was the constant vacuum from the AOS. If it would have gone to the track and saw one heavy, high RPM deceleration it would have been ejected from the crankcase.


We'll be going back together with it in a couple of weeks. The good news is the crankshaft passed magna flux and we caught two valve seats in the heads that were loose before they gave him a really nasty experience.

mklein9

The people you see are, by definition, the people who currently own running cars. That's a heck of a selection bias.

There is no question that a large number of engines live perfectly fine lives for many miles. But because most of us have woefully inadequate training in statistics, we fail to make appropriate conclusions given incomplete or biased data.

Gonzo911

The data isn't always biased. Its the interpretation of the data that is the issue. And therefore, the conclusions.

You experienced a major issue with your 996 engine. Jake works on broken engines all the time. Your perceptions are skewed.

If 5.2% of all 996's fail (totally made that up of course since no one knows for sure), then some people would "reason" that this is a low number...nothing to worry about. Others would say "holy crap!!!" and take drastic measures to protect their car and finances. That is why these threads bring out such diverse opinions.

As previously stated, most 996 owners are blissfully unaware of the any issues, or of Rennlist, or of Flat 6 Innovations, etc. Good for them.

In AZ, when someone sees a snake, it is always a rattlesnake..

As for statistics relating to failure, when a 996 engine fails, I would venture that the quick diagnosis is always the IMS, either due to a lack of knowledge or greed by the dealer/Indy. After all, as Jake often mentions, there are many, many more modes of failures than the IMS. Bottom line. There are no statistics on 996 engine failure (other than the extremely scientific poll at the top of our forum )

So, IMHO, the "bias" is built on not only misinformation but a lack of information. Also, there really is not reliable failure data. Couple that with personal experience/tolerance and at the end of the day you do what you feel you need to do for your car, your wallet and your piece of mind. After all, that's all that really matters.

roadsession

GOLD

Torontoworker

Um, y.e.s. we do...

It was '****** Boy' (aka Wendelin Wiedeking) whom is now in the pizza business and is also awaiting a German court decision.

Flat6 Innovations

Like I've said over and over again.... We are certainly biased. We don't see the cars that are healthy and we turn down regular types of service and maintenance because our facility is filled with "less than favorable issues" or "complete losses". Quote honestly we don't care about doing the work that any other shop can do, and we send cars away all the time that can be repaired or serviced at a normal shop level. We are accustom to chunks of metal coming out with the oil when its drained and thats the type of oil service that we appreciate.

I've never cared about doing normal work with cars or engines, if its not a challenge, or a mystery, its too boring to be here. We specialize in resurrections and reconstructions along with performance, thats the fun stuff.

DaveCarrera4

Jake, thank you for that. I think this is what so many of us were hoping to have you say at some point!

2003 Carrera 4S Speed Yellow / 1955 356 Continental 1500 Rust Red

Flat6 Innovations

I've said it dozens of times here.

TSMacNeil

This whole scenario is fairly easy to explain.

I'll use my job as an example.
I'm an airline pilot. I fly 1000 hours a year, which is essentially 40,000 miles per year. Generally uneventful.
(Like most 996 ownerships)

Rare as it may be, when an airliner crashes, it's a big deal...call it catastrophic.
(like a M96 grenading)

I have friends who are NTSB crash investigators...they only get called to duty under horrible circumstances. Their job is to determine what went wrong. That's all they do...evaluate disasters.
(Like Raby)

So, when I talk to my NTSB friends, they all talk about disasterous things...since that's all they see.
(Like Raby)

The only real difference for me is my NTSB friends don't habitually show me their pictures of crash sites.

(unlike Raby)

Ahsai

^^like

aviography

Crash investigators do share their findings of the cause of the crash illustrated with appropriate images, because that is their obligation, and people want to know.

(Like Raby)

NTSB investigators do not habitually post crash site images unless required for the post-crash investigation report, because often there is lost of life, posting frivolous crash site images would cross the line of professionalism.