How is Longevity on the New 911 Engine (1999) vs. the Old One?

[I Wanna 911]

Hi, Everyone:

I started a new thread about a week ago comparing the G50 vs the 996 model? I'm kinda new to the Porsche universe, so I was astounded to hear from other members that some of the older, originally-designed aircooled engines can, if well maintained, hit 400,000 miles That is truly stunning.

Although I plan to eventually purchase an aircooled car, it looks like budget will limit me to a 996 as a first step.

Since the new powerplant has now been around for more than twenty years, what's the longevity on the new, water-cooled engines? The reason I ask is there are a lot of 996s out there in the market at very attractive prices with around 100,000 miles on the motor.

Thanks in Advance for Your Response,
Scott M.

[Coastr]

They can both be unreliable, they can both run for many 100s of thousands of miles. Climate, service, treatment - these all matter.

Air cooled engines break head studs and wear out valve guides. Water cooled engines score bores and eat IMS bearings. Do your research.

Arguably the best is the water cooled metzger engine which is the air cooled case, but water cooled. But you need a turbo or gt3 to get one of those.

[88911coupe]

The critical flaw in normally aspirated 996 engines is the intermediate shaft bearing. Do a search for Porsche IMS issues. There is a TON of info. There are solutions from Jake Raby however won’t fix and engine already damages and not cheap. Note the 996 Turbo is a totally different engine and one of the all time great Porsche engines...aka Metzger engines.

[eastbay]

Originally Posted by 88911coupe

The critical flaw in normally aspirated 996 engines is the intermediate shaft bearing. Do a search for Porsche IMS issues. There is a TON of info. There are solutions from Jake Raby however won’t fix and engine already damages and not cheap. Note the 996 Turbo is a totally different engine and one of the all time great Porsche engines...aka Metzger engines.

Well, besides cracked or scored bores and cylinder head cracks, pretty solid, eh?

As said above, if you are worried about 99x engines, buy the Turbo. Few more bucks up front and a lot less issues and worries. If you can find a good one that is not flogged out.

[I Wanna 911]

Sorry I left this out of my OP, but I'm totally up to speed on the IMS bearing issue in the 996 era. Apologies for not including that. And almost every car I've seen for sale specifically mentioned that this has already been addressed and fixed.

So, assuming that is the case, what other issues might cause problems in a 996?

Thanks for all your posts.

Scott

[Driven97]

Sounds like you want someone to hold your hand and tell you the M96 is a stout motor. It's, uh, ok. What makes it hurt is if it goes pop, it's real expensive. Not like a Miata where you can go grab a spare at a junkyard for a couple hundred bucks. Same goes for any Porsche motor though - they're all very expensive to repair / replace.

Failure causes are the same as for any motor. Poor maintenance, old oil, high temps, over-revs, neglect, beating on it before it reaches optimal temp, etc.

What's fun about the M96/M97 is that babying it is an additional abuse. Garage queens that weren't taken for regular proper exercise seem to have exceptionally high instance of issues.

In general, there's more >100k mile air cooled cars than 996s out there, but both exist.

[I Wanna 911]

Originally Posted by Driven97

Sounds like you want someone to hold your hand and tell you the M96 is a stout motor. It's, uh, ok. What makes it hurt is if it goes pop, it's real expensive. Not like a Miata where you can go grab a spare at a junkyard for a couple hundred bucks. Same goes for any Porsche motor though - they're all very expensive to repair / replace.

Failure causes are the same as for any motor. Poor maintenance, old oil, high temps, over-revs, neglect, beating on it before it reaches optimal temp, etc.

What's fun about the M96/M97 is that babying it is an additional abuse. Garage queens that weren't taken for regular proper exercise seem to have exceptionally high instance of issues.

In general, there's more >100k mile air cooled cars than 996s out there, but both exist.

Nope, no hand-holding at all. I prefer straight talk, unvarnished truth. I'm asking the question merely because several folks in another one of my threads told me that the early aircooled powerplants -- 915s and G-50s, for example -- have been known to go 400,000 miles if properly maintained.

I used to build old VW aircooled engines so I'm comfortable around these things, but this kind of rebuild, at least for the block, would not be something I'd venture into. In SoCal I can almost throw a dart and find a great 911 independent P house, so just seeking general info here.

I'm an academic by training and do a ton of research. I LOVE research. Part of that research -- the most important part -- is talking to people with more knowledge and experience than me, which I've been shy to do. How else does one learn?

Thanks for your post.

Thanks,
Scott

[Jeff Alton]

All Porsche engines have had issues....

Thermal reactors on 2.7 engines, valve guides on 3.2 engines, head studs on 3.0 engines, head stud pulling threads on mag cased engines, mechanical chain tensioners, 964 cylinder head to cylinder leaks, 993 SAI issues, to name but a few..... lol

A larger bore M96/97 engine is more likely to score a cylinder than $hit the IMSB. Yes, IMSB failures are all the rage, and they do fail. But bore scoring is an issue as well. Both failures require engine tear down and a big chunk of $$ to fix.

The difference is that many M96/97 failure repairs can exceed the value of the car. With the value of aircooled cars, that is not likely currently.

Cheers

[I Wanna 911]

Originally Posted by Jeff Alton

All Porsche engines have had issues....

Thermal reactors on 2.7 engines, valve guides on 3.2 engines, head studs on 3.0 engines, head stud pulling threads on mag cased engines, mechanical chain tensioners, 964 cylinder head to cylinder leaks, 993 SAI issues, to name but a few..... lol

A larger bore M96/97 engine is more likely to score a cylinder than $hit the IMSB. Yes, IMSB failures are all the rage, and they do fail. But bore scoring is an issue as well. Both failures require engine tear down and a big chunk of $$ to fix.

The difference is that many M96/97 failure repairs can exceed the value of the car. With the value of aircooled cars, that is not likely currently.

Cheers

Jeff, thanks for your post. Important matters to consider.

Scott

[proporsche]

Originally Posted by I Wanna 911

Nope, no hand-holding at all. I prefer straight talk, unvarnished truth. I'm asking the question merely because several folks in another one of my threads told me that the early aircooled powerplants -- 915s and G-50s, for example -- have been known to go 400,000 miles if properly maintained.

I used to build old VW aircooled engines so I'm comfortable around these things, but this kind of rebuild, at least for the block, would not be something I'd venture into. In SoCal I can almost throw a dart and find a great 911 independent P house, so just seeking general info here.

I'm an academic by training and do a ton of research. I LOVE research. Part of that research -- the most important part -- is talking to people with more knowledge and experience than me, which I've been shy to do. How else does one learn?

Thanks for your post.

Thanks,
Scott

Scott....

yes ,the 911 engine will go that far look at my signature...
Back in the 1990 if you got a 996 and had less then 50k on it -if it made it that far- the Porsche dealer would give you new engine on warranty.
For the valve guides on Carrera..it was mainly from 1987 where the Porsche had changed the valve guides material-for some unknown reason.I did a valve jobs on 1987 model with less than 20K on the speedo on several occasions.
964 1989-90 had problems with leaking engines ,that was due to none loctite on the engine case.....got that from a friend who was mechanic at the factory-no names;-)
The best bet is like this every model in its `1st year of production is the worst and the best is always the last year of production....

Ivan

[sugarwood]

The 911 can be a very reliable car but this "bulletproof" mythology really needs to stop.

Bulletproof......

Except if you have pulled or snapped head studs.
Except if you have a failed chain tensioner.
Except if you have an exploding air box without popoff valve.
Except if you have worn valve guides.
Except when you need the 915 synchros replaced.
Except when you have the exploding rubber centered clutch.
Except when the Targa top leaks.
Except when the A/C doesn't work.

No car ever made is bulletproof, especially the 911 with its engine out $5,000 gearbox and $10,000 topend services.