Engine Serial Number Questions

Hi, I have a 2004 996, with a remanufactured engine. The key part of the serial number is M96/03AT665, followed by 5 numbers that I suspect are just sequential as they remanufacture motors. From my searches here, I believe that this indicates the following: It's an engine for a 996, specifically the M96/03, 3.6 liter putting out 320hp AT indicates that it's rebuilt 665 indicates that it's a 2005 motor From reading many, many threads, here and elsewhere, it appears that this is a late rebuild, probably from 2009 or later. it also appears that it has a serial number higher than (after) some known to have the so-called "big bearing," and that it was installed in 2010 or so. I infer from all this information that my motor, which has never had even one fleck of metal in the oil, has the big-bearing, and that I should leave it alone unless I'm changing the clutch or see some metal in the oil. Thanks! Mark

So what is/are the questions? Seems you have everything figured out already.

Judging by your research, it seems you're looking for validation of your theories. Unfortunately, while your deductions seem plausible the chances of getting anything definitive are slim - good luck

I think you're right about the engine codes, but what I've been told is that you can't assume which IMS bearing you have. I was told that with a 2005 code engine, regardless of when it was installed, it is a crap shoot. I was told the way to know is if you remove the transmission and see the size of the nut on the IMS flange - if it is the 22 mm nut, you have the newer bearing that requires the cases to be split to R&R the bearing. Anything else is just guessing. But I'd be happy to be corrected (I have a 2005 code AT engine in my 2002, installed in 2007).

Yeah, I was hoping for some sort of confirmation. I called the local independent Porsche shop, which enjoys an excellent reputation. They said that, with situations like mine, they recommend not doing anything until it needs a new clutch, at which point they can examine the area to see what's in there. What a mess; Porsche just should have recalled the cars, IMO.

Drive it as much as you can, and change the oil every 4k miles until you do the clutch change. If it turns out to be the big bearing you count your blessings. If not, you decide which replacement bearing (If you want to keep the car, do The Solution) you want to use, and go from there...

Yeah. Oddly enough, I'm not concerned enough to have done anything in the 5 years we have owned the car. The pot odds (paying $3000 to fix it, vs. seeing what happens on a car worth only $25,000 relating to a problem affecting only about 5% of the cars) strongly suggest watching the oil (I change it every 3,000 miles, and have never seen a metal fleck). But we want to sell the car, and buyer are spooked.

Yeah, that's the thing about buying and selling these cars. You just need the right buyer. I just paid a pretty good price for a car with a known not replaced factory bearing. To me the low mileage AT was worth more than the IMSB concern. Options: price the car knowing people are likely to negotiate you down because of the unknown IMSB, drop the sale price to meet the buyer, have the bearing replaced or keep shopping for a new buyer.

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My father just bought a 2007 Honda Civic with 161,000 miles. Guess what?? I saw the paperwork and I just couldn�t believe it, but it�s totally true. The local Honda dealer replaced the engine in January 2017 with a 100% brand new short block and water pump (not a re-manufactured engine) and changed all the bolts/gaskets in the engine at 153,000 miles for 100% FREE due to a manufacturing defect in the aluminum block. AT 153,000 miles. 153,000 miles at the Dealer. And Honda did this for everybody with a Civic regardless of the mileage if it was less than 10 years old. Compare this with Porsche, which told all of us to go pound sand with their IMS manufacturing and design defect. Civic re-sale values did not collapse like the 996/997. That 8th generation Civic my dad bought is still holding up normally in the used car market. Lastly, I strongly discouraged him from buying the car (because I thought the car having a new engine was just a BS line everybody uses), but his Honda at 163,000 miles drives, sounds and feels brand new. Even the interior buttons feel and sound new. The car just doesn�t look anything new. All amazing compared to our expensive Porsche and Porsche forcing us to find nutjob solutions that may or may not work (NO IMS replacement has ever gone over 100,000 miles that I�m aware of and some have imploded too). Standing behind your product: HONDA 1,000,000 PORSCHE 0

NO IMS replacement has ever gone over 100,000 miles that I’m aware of and some have imploded to o. They weren't designed to!

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I think that was the point he was trying to make! I think Honda can well afford to do the repairs / replacement as they are a huge manufacturer. Porsche on the other hand, especially when the 996 came out was a small specialty manufacturer and was on the verge of bankruptcy. I think the costs of replacing engines would have killed them let alone redesigning a new engine that isn't so prone to CEF's. The bottom line is Porsche is still around and stronger than ever so they got away with it. It sucks for us but if the cars didn't have these issues how many of us would have been able to afford one? Look at the prices of 993's and 997's.

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^^ True.

As a datapoint, my 2000 996, with reman M96/04AT66Y66483 has the 22mm IMS flange nut. Current state (Feb. 19, 2018)

So code Y is an engine built in 2000, and it has the 22mm nut. Do you know when it was installed? I have a code 5, like the OP, which I believe means the engine was built in 2005, and it was installed in 2007. I haven't had it apart, so I have no idea what bearing it has, but I am soooooo curious. With 30K on the clutch, I don't think I'll need to split it any time soon, but curiosity may get the better of me... Here is a great post with the breakdown of decoding the engine: https://www.renntech.org/forums/topi...e-sn-decoding/ And this too: https://www.renntech.org/forums/topi...number-decode/ This might be a fun thing for some data guru to make a database on - engine serial number, type of IMS bearing, etc.

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Sorry, I do not have a date. OP, what are the last 5 digits of the serial number?