996 reliability
Discussion
DucatiGary said:
I would never buy any car if I listned to all the crap on here.
if you want it but it, enjoy it and if you break it, fix it.
if you want it but it, enjoy it and if you break it, fix it.
Amen to that. I've never read so much crap anywhere than on the forums that a 996 is a financial timebomb
My 996 has been 100% reliable in the 3 years i've had it. From runs to the shops in the snow and 170 mph runs back from holiday . With only wear and tear items needing replacing.
I didn't post here yesterday ... Y'know why??
Unbelievably , my engine refused to explode..
I can only imagine that there's a couple of thousand other 996 drivers out there that would very quickly turn to the Internet for advice if their oily bits went pop... I'm not hearing anything from them either.
I genuinely feel really bad for the couple of people posting who have had engines blown , and I'm not trying to take from what is obviously a bloody awful situation..
But to rest of you doomsayers and part time BS merchants .. I say to you
BUGGER OFF ................
Unbelievably , my engine refused to explode..
I can only imagine that there's a couple of thousand other 996 drivers out there that would very quickly turn to the Internet for advice if their oily bits went pop... I'm not hearing anything from them either.
I genuinely feel really bad for the couple of people posting who have had engines blown , and I'm not trying to take from what is obviously a bloody awful situation..
But to rest of you doomsayers and part time BS merchants .. I say to you
BUGGER OFF ................
ballcock said:
I didn't post here yesterday ... Y'know why??
Unbelievably , my engine refused to explode..
I can only imagine that there's a couple of thousand other 996 drivers out there that would very quickly turn to the Internet for advice if their oily bits went pop... I'm not hearing anything from them either.
I genuinely feel really bad for the couple of people posting who have had engines blown , and I'm not trying to take from what is obviously a bloody awful situation..
But to rest of you doomsayers and part time BS merchants .. I say to you
BUGGER OFF ................
Unbelievably , my engine refused to explode..
I can only imagine that there's a couple of thousand other 996 drivers out there that would very quickly turn to the Internet for advice if their oily bits went pop... I'm not hearing anything from them either.
I genuinely feel really bad for the couple of people posting who have had engines blown , and I'm not trying to take from what is obviously a bloody awful situation..
But to rest of you doomsayers and part time BS merchants .. I say to you
BUGGER OFF ................
Well said.
With all due respect, if you bought a 996 you either (a) accept that if it break you will have to pay to fix it, or (b) you buy the OPC warranty which covers all of the stuff on this thread, including engine failures [rare] and RMS [washed mouth out with soap])
If you can't do (a) and won't do (b) then you bought the wrong car, IMHO.
My 996 has run like a swiss watch ever since I bought it, save for a couple of niggles fixed foc without argument. I smell trolls, here.
Edited by Vesuvius 996 on Monday 31st July 10:39
I am new to this forum.
I was just advised by Pepe Porsche (White Plains, NY) that the engine on my 2002 911 (29,000 miles)has to be replaced because the intermediate shaft bearing broke. This is exactly four months after the rear seal was replaced.
The car has not been driven "hard" by any means, and never red-lined (to my knowledge).
It seems like I might be another victim of "RMD" syndrome.
Any advice???
Thanks
I was just advised by Pepe Porsche (White Plains, NY) that the engine on my 2002 911 (29,000 miles)has to be replaced because the intermediate shaft bearing broke. This is exactly four months after the rear seal was replaced.
The car has not been driven "hard" by any means, and never red-lined (to my knowledge).
It seems like I might be another victim of "RMD" syndrome.
Any advice???
Thanks
Although engine problems are statistically very rare - there are a few design features that seem odd and that keep failing on those few that break down.
The intermediate shaft bearing is grease filled and shrouded which means that from new it would not allow fresh cool oil to flow in and out while the engine is running. Indeed when they are stripped down - inside the hollow shaft there is a load of old trapped engine oil that has gradually seeped in.
When they fail it is usually a metal fatigue failure of the ball outer track - which is also odd because it is not really subjected to any side load of any significance.
It could be that the bearing overheats through lack of a plentiful cool oil supply and the pressure from it running tight causes the loads that result in the metal fatigue.
Furthermore if you calculate the speed that it runs at (which is not half engine speed but between engine and half engine speed) it is actually close to (or over) the rotational speed limit for a grease filled bearing of that size (which is lower than an oil filled speed limit for the same bearing). If this is so - overspeeding an engine may indeed be the start of problems with the bearing.
I spoke to a representative of the bearing manufacturers to ask why it is grease filled and the answer I got was that they themselves thought that it should not be.
While I agree that an engine left for years and never turned over may eventually drain oil out of the bearing there would still be some left in the bottom of the ball bearing groove to lubricate it on start up so I cannot understand why this bearing was ever specified to be grease filled and shielded.
Far be it for me to infer that I know better than the designer of the engine (and I am not trying to do that - perhaps there is some good explanation) - but it is very odd (especially as the other end of the same shaft is just a plain round steel spigot ruuning in a machined aluminium hole) and it is not something I would have done in the same position - yet it seems to be appearing on every design change to the general bearing layout (as it has changed from a double to a single row bearing etc) without addressing what I see as the main fault.
However Porsche seemed to have made a few other odd design decisions that they have acknowleged and changed - that I doubt many other people have discovered. For example very early cylinder head bolts had smaller torx heads and often the torx bit would break when trying to undo them - this was soon increased to the next size up on all models. Then the main bearing shells had no effective location to stop them spinning (doubling up the centre oil groove as a location)- also soon changed. Early 2nd motion timing chains had the size of the hydraulic tensioner piston reduced on one bank (that most frequently suffered premature chain or slipper pad failure)although the grooves that identify them were kept the same and I can find no reference to it being a different design. The plastic spark plug hole tubes have also been replaced by a cast alloy tube in the 3.6 - good that one does work better!
All these changes are things you only find out after working on older and then newer engines and following the changes and working out why they were made in comparison to the failures you have experienced - and there are many other minor alterations that only come to light if you strip and rebuild many engines as we have.
The reduced wall thickness of the cylinder wall on 3.4 and 3.6 engines (compared to the 2.5, 2.7 and 3.2 Boxster variants) is also odd and may contribute to those that crack prematurely - although the Lokasil system does provide a superb cylinder bore finish that almost lasts for ever if it doesn't crack (which may well be isolated to those with some minot manufacturing imperfection that time will cure with this new casting technology). It is a shame that they all seem distort oval but if the engine is ever stripped we can now re-round those bores and support them to prevent future failures.
The RMS failures reflect the basic problem with the design using a hole to locate the seal that was machined in one set of cases while the crankshaft main bearing locations were machined in a different set of castings and the 2 do not always line up perfectly on assembly while there is no easy way to get the seal square either. Later 997 seals are designed to allow the seal to move its position and set itself in line again - but has no spring to retain sealing pressure - again an understandable mod with an imperfect result.
These engines are wholly new designs and incorporate many superb features put in to make them last for a long time and there are just a few "weak spots" that are inevitable in any new design and that Porsche do seem to be working through - bit by bit - improving most of the problems but still inexplicably seemingly doing little about some of the others.
With most early 911's and 944/968 variants - needing top end or full engine work at some time in their long life the new engines are little different. They have lighter internals and run with lower emmissions and are still by far (in my opinion) the mosr reliable very high performance sports car engine you can buy and find local dealers to look after at reasonable costs.
In time more specialists will be able to offer rebuild services and so - in my humble opinion - we must just allow Porsche to work through the changes and put up with the very rare problems that come with new manufacturing techniques and a new engine range. Protection from warranties etc are available for those who want to avoid the cost of a rare failure - up to 10 years old from Porsche or even with no age limit from us.
More info and pictures about engine issues may be found on our web site www.hartech.org
Baz
The intermediate shaft bearing is grease filled and shrouded which means that from new it would not allow fresh cool oil to flow in and out while the engine is running. Indeed when they are stripped down - inside the hollow shaft there is a load of old trapped engine oil that has gradually seeped in.
When they fail it is usually a metal fatigue failure of the ball outer track - which is also odd because it is not really subjected to any side load of any significance.
It could be that the bearing overheats through lack of a plentiful cool oil supply and the pressure from it running tight causes the loads that result in the metal fatigue.
Furthermore if you calculate the speed that it runs at (which is not half engine speed but between engine and half engine speed) it is actually close to (or over) the rotational speed limit for a grease filled bearing of that size (which is lower than an oil filled speed limit for the same bearing). If this is so - overspeeding an engine may indeed be the start of problems with the bearing.
I spoke to a representative of the bearing manufacturers to ask why it is grease filled and the answer I got was that they themselves thought that it should not be.
While I agree that an engine left for years and never turned over may eventually drain oil out of the bearing there would still be some left in the bottom of the ball bearing groove to lubricate it on start up so I cannot understand why this bearing was ever specified to be grease filled and shielded.
Far be it for me to infer that I know better than the designer of the engine (and I am not trying to do that - perhaps there is some good explanation) - but it is very odd (especially as the other end of the same shaft is just a plain round steel spigot ruuning in a machined aluminium hole) and it is not something I would have done in the same position - yet it seems to be appearing on every design change to the general bearing layout (as it has changed from a double to a single row bearing etc) without addressing what I see as the main fault.
However Porsche seemed to have made a few other odd design decisions that they have acknowleged and changed - that I doubt many other people have discovered. For example very early cylinder head bolts had smaller torx heads and often the torx bit would break when trying to undo them - this was soon increased to the next size up on all models. Then the main bearing shells had no effective location to stop them spinning (doubling up the centre oil groove as a location)- also soon changed. Early 2nd motion timing chains had the size of the hydraulic tensioner piston reduced on one bank (that most frequently suffered premature chain or slipper pad failure)although the grooves that identify them were kept the same and I can find no reference to it being a different design. The plastic spark plug hole tubes have also been replaced by a cast alloy tube in the 3.6 - good that one does work better!
All these changes are things you only find out after working on older and then newer engines and following the changes and working out why they were made in comparison to the failures you have experienced - and there are many other minor alterations that only come to light if you strip and rebuild many engines as we have.
The reduced wall thickness of the cylinder wall on 3.4 and 3.6 engines (compared to the 2.5, 2.7 and 3.2 Boxster variants) is also odd and may contribute to those that crack prematurely - although the Lokasil system does provide a superb cylinder bore finish that almost lasts for ever if it doesn't crack (which may well be isolated to those with some minot manufacturing imperfection that time will cure with this new casting technology). It is a shame that they all seem distort oval but if the engine is ever stripped we can now re-round those bores and support them to prevent future failures.
The RMS failures reflect the basic problem with the design using a hole to locate the seal that was machined in one set of cases while the crankshaft main bearing locations were machined in a different set of castings and the 2 do not always line up perfectly on assembly while there is no easy way to get the seal square either. Later 997 seals are designed to allow the seal to move its position and set itself in line again - but has no spring to retain sealing pressure - again an understandable mod with an imperfect result.
These engines are wholly new designs and incorporate many superb features put in to make them last for a long time and there are just a few "weak spots" that are inevitable in any new design and that Porsche do seem to be working through - bit by bit - improving most of the problems but still inexplicably seemingly doing little about some of the others.
With most early 911's and 944/968 variants - needing top end or full engine work at some time in their long life the new engines are little different. They have lighter internals and run with lower emmissions and are still by far (in my opinion) the mosr reliable very high performance sports car engine you can buy and find local dealers to look after at reasonable costs.
In time more specialists will be able to offer rebuild services and so - in my humble opinion - we must just allow Porsche to work through the changes and put up with the very rare problems that come with new manufacturing techniques and a new engine range. Protection from warranties etc are available for those who want to avoid the cost of a rare failure - up to 10 years old from Porsche or even with no age limit from us.
More info and pictures about engine issues may be found on our web site www.hartech.org
Baz
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