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Flaws: 996 vs 996TT


Silver_TT

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I'm not in a rush but I've been considering selling my 2002 4S and getting a 996TT with X50 -- nothing wrong with my 4S in the least, I just want more horsepower. I'm intimately familiar with the 996 and I know what the common issues and design flaws are (IMS, blah blah blah). I've fixed a lot of the things on the car myself and it's a fantastic vehicle. I've read a lot about the Turbos but not owning one, I haven't paid as close attention over the years. I was wondering if anyone could articulate what the shortcomings and common issues of the 996 Turbo are. I've read that these 996TT engines are "bulletproof" but surely there has to be at least some issues. I was wondering what those issues were and how severe each is.

I wanted to get clarification on this because I've searched and looked on other sites like 6speed and saw conflicting information. Really annoying when people make statements or talk about things they really aren't qualified to opine on (therefore perpetuating false rumors).

Thanks in advance.

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Thanks a lot for the response and for pointing to that thread, I had not seen that before.

Is this a comprehensive list of known Turbo issues? Because I don't see anything on that list that I would really consider as "major", like IMS.

The window regs, oil pressure sensor, alternator, etc are all common to the 996 as well, but I don't really consider those major issues. Any mechanical thing is going to have pump and sensor failures. I'm more concerned with things that could destroy or significantly damage an engine (ie. $$$$$$$).

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Is this a comprehensive list of known Turbo issues? Because I don't see anything on that list that I would really consider as "major", like IMS.

The Turbo uses the Metzger design engine, which is completely different than the M96/97 engine found in all the 996's. While it does have a lay shaft, it is pressure lubricated and relatively bullet proof, as is the rest of the engine. Read up on the Metzger engine, it had a true dry sump system and a lot of other improvements over the M96/97, which is why a replacement costs north of $50K.

car_photo_306619_25.jpg

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I keep hearing of folks that want to do Forced Induction on their M96 engines.

I tell them for the price of what its going to cost you, sell the 996/7 and buy a 996TT.

There any many little things in common with the 996, but like has been said the engine is not from the same base design.

Any issues with the Turbo and cylinder head cracks or cracked cylinder liners?

Mike

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Thanks, JFP, always value your input. Yes, I have read about the Metzger engines and I know they are legendary.

So that said, I realize the engine is completely different. As Mike questioned, I was just wondering if there were any specific weaknesses I should be aware of in the engine design specifically. I realize there will be other little issues like the window regulators or whatever, and I apprecaite those being pointed out very much, but at this point I'm more concerned with the fundamental design of the engine. At the $50K that JFP cites, I want to know what I'm getting into. I have really gotten into tracking my car and I know at some point I will outgrow my 4S, as much as I love the thing to death. The 996 Turbo with X50 seems like a very affordable upgrade when I'm ready. Every car is going to have little things here and there, they are machines, but I want to make sure the the engine is completely sound, especially since I would look for one with higher mileage (~75K+ miles).

Also agree that forced induction on a M96 is a stupid thing to do for a number of reasons.

Thank you to all for your input.

Edited by ferrugia
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I keep hearing of folks that want to do Forced Induction on their M96 engines.

I tell them for the price of what its going to cost you, sell the 996/7 and buy a 996TT.

There any many little things in common with the 996, but like has been said the engine is not from the same base design.

Any issues with the Turbo and cylinder head cracks or cracked cylinder liners?

Mike

Not really, unless you go nuts with the boost levels. The components were designed for ruggedness and racing use, castings are thick where they need to be, and proven over years of hard running. Basically, the factory broke just about everything that could fail, and then improved it.

Running just about any level of boost on a M96/97 is asking for problems and shortening the engine's life expectancy.

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Thanks, JFP, always value your input. Yes, I have read about the Metzger engines and I know they are legendary.

So that said, I realize the engine is completely different. As Mike questioned, I was just wondering if there were any specific weaknesses I should be aware of in the engine design specifically. I realize there will be other little issues like the window regulators or whatever, and I apprecaite those being pointed out very much, but at this point I'm more concerned with the fundamental design of the engine. At the $50K that JFP cites, I want to know what I'm getting into. I have really gotten into tracking my car and I know at some point I will outgrow my 4S, as much as I love the thing to death. The 996 Turbo with X50 seems like a very affordable upgrade when I'm ready. Every car is going to have little things here and there, they are machines, but I want to make sure the the engine is completely sound, especially since I would look for one with higher mileage (~75K+ miles).

Also agree that forced induction on a M96 is a stupid thing to do for a number of reasons.

Thank you to all for your input.

All of the Porsche street cars share components like window regulators, electrical switches, and sensors; it would be too expensive to do otherwise. So some of the sensors and electronic bits have similar failure rates in the Turbo or GT2 as a 996/997. But the engines in the Turbo and GT2 cars are a unique mechanical design honed over years of hard core racing, and share just about nothing with the more "pedestrian" M96/97 engines. Can you break a Metzger lump? Sure, if you try hard enough or go completely nuts with it; which is why PCNA has a replacement engine program for them. So if you want to take one of the Metzger’s and take it to the limit, just bring money, lots of money........... :eek:

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Ok I see, you are looking at major concern. In that case you should look at this thread from haulinkraut and the links he is referring to: http://forums.rennlist.com/rennforums/996-turbo-forum/628070-can-we-lay-all-the-cards-on-the-table-with-996tt-engine-concerns.html

Porsche Doc has a very good thread about cam rings failure: http://forums.rennlist.com/rennforums/996-turbo-forum/600739-error-code-p1325.html

The problem with cam failure is you need very expensive special tooling to time the cams at reinstallation....

Agree with the last post from JFP and please be very careful when you read in certain forums about the TT engine being bulletproof. Many people on 6speed, Rennlist and Renntech discover the fact the TT can be very expensive to maintain or to keep alive......

Don't get me wrong, I love my car but very early found that I need the repair manual asap and a good place to get parts at a good price ;-) And people like here on Renntech to help me for troubleshooting.....

Edited by jpflip
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Normal 996 and 996 Turbo is like comparing apples to orangutan's... at least when it comes to drive train. Interior and body are the same but that is where the likeness stops. Common issues with the 996 Turbo are piddly compared to common issues with the M96 in the 996. The Turbo does have some quirks but nothing that is catostophic like the M96 has.

I'll list a few, and these are just the ones I've ever heard of, and some I experienced.

*Coolant Pipes dislodge from Motor... sounds more scary than it really is. Z Germans for some reason decided to use some sort of lock-tite type glue to hold the coolant pipes inside the motor, with repeated heat cycles and time, it wears out and spits the coolant pipes out of the motor. Now this isn't a coolant hose, it's the actual pipe that sticks out of the engine block that the hose attaches to. So when one blows out, you loose all of your coolant in a matter of seconds...ask me how I know. Now the Turbo's aren't the only car with this problem, all of the Mezger engine cars have it. In fact, it's probably more common on the GT3's and that includes the 997.1 and 997.2 versions. I've heard of it happening to newer GT3's with only 15K miles or so. Of course those cars were tracked regularly. But I don't think it's a mileage issue as much as time. My old car did it at around 55K and a friend of mine's did it at 28K, but they were the same age car. I even hear that some Porsche Club's won't allow Mezger engined cars in their track days unless it's been fixed.... so what's the fix? Simple... sort-of. You have them removed and have these http://www.torquesolution.com/product-p/ts-por-001.htm welded on.

This is a very common problem.

*Clutch accumulators... start to leak after awhile, simple replacement. Stupid things... some people get rid of them and swap over to a GT2 Master & Slave cylinder that isn't "assisted." This is also common.

*Fluid migration from steering pump reservoir to clutch system reservoir, if you don't catch it in time sometimes you have to replace both power steering pump and clutch slave cylinder. This is not common but can happen.

*Coolant bottle leak... common problem.

*Coolant leaks... random places. not real common, if you don't count the coolant pipe issue or the tank.

*Window regulators...not a big deal, just a PITA. fairly common.

*Sunroof drains break, fairly common, happens with age... Porsche updated the whole sunroof cassette and parts.

*Ignition switch, probably the cheapest fix, $10 part, fairly common.

*Some people have problems with their transmissions popping out of gear, I never did, but it was hard to get into 1st gear sometimes, although my current 997 is actually worse than my Turbo was.

All in all, I'd say a 996 Turbo is more reliable than the 996's and the 997's.

I've seen examples of stock, non-modified Turbos with 300K + miles. That's awesome! The motor is detuned at 450 HP so if left alone it should last a LONG LONG time.

The last GT2RS, uses the same motor and it's putting out 620 HP. They didn't use the newer 9A1 derived Turbo motor (DFI) they went back to the Mezger GT1 engine for that car...hmmm, must be because it's Awesome.

I worked for PCNA when Toyota was hired to help them LEAN up their manufacturing and one of the areas Toyota thought Porsche was crazy for, was the Mezger engine. They didn't understand why a company would build such a highly complex and expensive motor. Hence why Porsche went away from dry sump engines in their normal cars. Toyota conviced them that normal people don't need such highly engineered engines and that they could save gobs of money by simplifying it and only using the expensive engines in their true performance models like the GT3 and Turbo.

Which eventually became just the GT3 when the Turbos even went away from dry-sump in 2011. Now everyone is waiting on baited breath for the next 991 GT3 to see what motor it has, and if it has a true dry-sump system.

The motor in the 996 Turbo X50 is a $50K to $60K engine... the M96 and M97 motor from a 996 and 997 and the 9A1 motor from the 997.s and 991 are aprox. $23K to $30K motors.

Think there's some build quality differences?!

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*Coolant Pipes dislodge from Motor... sounds more scary than it really is. Z Germans for some reason decided to use some sort of lock-tite type glue to hold the coolant pipes inside the motor, with repeated heat cycles and time, it wears out and spits the coolant pipes out of the motor. Now this isn't a coolant hose, it's the actual pipe that sticks out of the engine block that the hose attaches to. So when one blows out, you loose all of your coolant in a matter of seconds...ask me how I know. Now the Turbo's aren't the only car with this problem, all of the Mezger engine cars have it. In fact, it's probably more common on the GT3's and that includes the 997.1 and 997.2 versions. I've heard of it happening to newer GT3's with only 15K miles or so. Of course those cars were tracked regularly. But I don't think it's a mileage issue as much as time. My old car did it at around 55K and a friend of mine's did it at 28K, but they were the same age car. I even hear that some Porsche Club's won't allow Mezger engined cars in their track days unless it's been fixed.... so what's the fix? Simple... sort-of. You have them removed and have these http://www.torquesolution.com/product-p/ts-por-001.htm welded on. This is a very common problem.

“Cold welding” or the combining of two metal components through the use of anaerobic type adhesives has been a failed experiment for several OEM’s, not just Porsche. The economic lure of the quick assembly of alloy components using low cost techniques and simple assembly hardware has been pretty much a complete failure for everyone that tried it. The heat cycling and pressure requirements over time were just more than the system could endure in some applications.

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