996-997 wet-sump engine reliability: enter your stats here!
Discussion
Hello,
I love my 1999 996 C2 (72k) for its balance of performance and practicality but just wish the mechanicals were something to be interested in rather than worry about!
The key jobs to address the common issues seem to be:
LN IMS (with clutch and flywheel if req)
Low Temp thermostat (or/and third rad?)
Full suspension re-bush (OEM or polybush)
Engine rebuild (preventative or failure)
Suspension refresh (bilsteins?)
Gearbox / Diff rebuild (as and when)
What I am not clear on is whether all of this work (particularly the engine rebuild) makes the 996 a modified, but still ultimately compromised, design or turns it in to the robust and reliable high performance vehicle we expect a Porsche to be. I would not expect, if I made all these changes to be worrying about back road acceleration / temp fluctuation and high rev gear shifts.
Your thougths would be appreciated.
I love my 1999 996 C2 (72k) for its balance of performance and practicality but just wish the mechanicals were something to be interested in rather than worry about!
The key jobs to address the common issues seem to be:
LN IMS (with clutch and flywheel if req)
Low Temp thermostat (or/and third rad?)
Full suspension re-bush (OEM or polybush)
Engine rebuild (preventative or failure)
Suspension refresh (bilsteins?)
Gearbox / Diff rebuild (as and when)
What I am not clear on is whether all of this work (particularly the engine rebuild) makes the 996 a modified, but still ultimately compromised, design or turns it in to the robust and reliable high performance vehicle we expect a Porsche to be. I would not expect, if I made all these changes to be worrying about back road acceleration / temp fluctuation and high rev gear shifts.
Your thougths would be appreciated.
Torque is good (it is what propels the car) and torque at high revs can also be good (if it is reliable as well and does not spin up the rear wheels). However while it is relatively easy to think up ways to pump more air into an engine - it is not as easy to get the extra exhaust out again - so many engines (without massive alterations to valve sizes and exhaust systems) strangle bigger turbos anyway and there seems to be a limit beyond which it can become impossible to go - whereas at the bottom end the exhaust system is easily able to cope and this is yet another reason why torque at lower revs can be so beneficial.
Although I wrote it many years ago (and it is a little out of date now) page 75 onwards of part 3 of our buyers guide on www.hartech.org - goes some way to explain the issues.
Furthermore the pictures below (sorry for the poor clarity) show the improvement that can be made by concentrating on the bottom end torque (as this 3 litre turbo was otherwise just the same as a 2.5 (turbo, exhaust, boost pressure etc etc) and was both easy to drive and extremely fast.
What I have not managed to do is to get a spreadsheet file to create a graph showing the rear wheel torque in each gear (as a vertical scale) and road speed (on the horizontal scale) as this is what propels the car along and the area underneath this graph is a reasonable picture of the thrust available in each gear and when to change gear. The difficulty is that the graphs generate automatically and of course while you can record details of engine speed and output - they apply to different road speeds and the system (or my lack of computer skills) has so far prevented me from displaying this nicely. I have a scan of such a graph but it will not upload for some reason.
Baz
Although I wrote it many years ago (and it is a little out of date now) page 75 onwards of part 3 of our buyers guide on www.hartech.org - goes some way to explain the issues.
Furthermore the pictures below (sorry for the poor clarity) show the improvement that can be made by concentrating on the bottom end torque (as this 3 litre turbo was otherwise just the same as a 2.5 (turbo, exhaust, boost pressure etc etc) and was both easy to drive and extremely fast.
What I have not managed to do is to get a spreadsheet file to create a graph showing the rear wheel torque in each gear (as a vertical scale) and road speed (on the horizontal scale) as this is what propels the car along and the area underneath this graph is a reasonable picture of the thrust available in each gear and when to change gear. The difficulty is that the graphs generate automatically and of course while you can record details of engine speed and output - they apply to different road speeds and the system (or my lack of computer skills) has so far prevented me from displaying this nicely. I have a scan of such a graph but it will not upload for some reason.
Baz
Edited by hartech on Friday 6th January 13:05
It can be difficult to differentiate between a lifter and piston slap - but if at tickover you look at the second hand of your watch and count the knocks - say for 5 seconds - then multiply by 12 - the answer will either be near 360 to 400 or 720 to 800 - the former being connected to a tappet and the latter to the piston or crank bearings.
If at camshaft speed (the slower one) it can be the lifter failed - a broken valve spring - a lose valve seat - a bent valve - etc.
Oil pressure falls at tickover when the engine is hot and hence if any bearings or tappets are worn that is when there may be too little hydraulic pressure to make them work properly.
There are also hydraulic tensioners on all 5 chains and they can get weak causing chain slap at low revs. even with a test rig (that we made) it is still not easy to identify which lifter is the problem - best isolate the area by sound and change all in that area.
Remember the hole in the housing that the tappet slides in may also be worn and may need checking.
Baz
If at camshaft speed (the slower one) it can be the lifter failed - a broken valve spring - a lose valve seat - a bent valve - etc.
Oil pressure falls at tickover when the engine is hot and hence if any bearings or tappets are worn that is when there may be too little hydraulic pressure to make them work properly.
There are also hydraulic tensioners on all 5 chains and they can get weak causing chain slap at low revs. even with a test rig (that we made) it is still not easy to identify which lifter is the problem - best isolate the area by sound and change all in that area.
Remember the hole in the housing that the tappet slides in may also be worn and may need checking.
Baz
hartech said:
It can be difficult to differentiate between a lifter and piston slap - but if at tickover you look at the second hand of your watch and count the knocks - say for 5 seconds - then multiply by 12 - the answer will either be near 360 to 400 or 720 to 800 - the former being connected to a tappet and the latter to the piston or crank bearings.
If at camshaft speed (the slower one) it can be the lifter failed - a broken valve spring - a lose valve seat - a bent valve - etc.
Oil pressure falls at tickover when the engine is hot and hence if any bearings or tappets are worn that is when there may be too little hydraulic pressure to make them work properly.
There are also hydraulic tensioners on all 5 chains and they can get weak causing chain slap at low revs. even with a test rig (that we made) it is still not easy to identify which lifter is the problem - best isolate the area by sound and change all in that area.
Remember the hole in the housing that the tappet slides in may also be worn and may need checking.
Baz
Thanks very much Baz especially on a Sunday!If at camshaft speed (the slower one) it can be the lifter failed - a broken valve spring - a lose valve seat - a bent valve - etc.
Oil pressure falls at tickover when the engine is hot and hence if any bearings or tappets are worn that is when there may be too little hydraulic pressure to make them work properly.
There are also hydraulic tensioners on all 5 chains and they can get weak causing chain slap at low revs. even with a test rig (that we made) it is still not easy to identify which lifter is the problem - best isolate the area by sound and change all in that area.
Remember the hole in the housing that the tappet slides in may also be worn and may need checking.
Baz
At this time my 2001 C4 996 has 110,000 miles and no serious problems. As I have explained earlier in this thread, I had the LN Engineering after market double race intermediate shaft bearing installed when I had the clutch replaced at 94,000 miles - the first clutch replacement, and it was at 94K miles still working and was not slipping. I recently purchased a 2005 997 C2 Cabriolet with PASM and Sport Chrono, full leather, Nav, Bose, etc. It has a very different feel than the 996. It is a very late production 2005 and has the 2006 improved bearing which is not retrofittable with the LN Engineering version. It is more refined and comfortable than my 996 in standard setting, i.e., with the "Sport" button not engaged. But, engage the Sport button and refinement and ease turns into brute force. WIth that button, it has two very different personalities; it is bipolar. The 996 feels and is simpler, direct and easy to drive. But, I truly prefer the 997, but only with PASM and Sport Chrono. The 996 is for sale only because I wanted a Cab and a perfect one was offered to me in Southern Florida. Cicerosecundus - New York. My 997 is so loaded with electronics that I am sure that I will have more trouble with it than I had with the 996.
Car now with Hartech awaiting full diagnosis though the symptoms point to the standard failure mode for 997 C2S. I wish I had read this thread before buying, I'd have a lovely e93 M3 (or maybe a CSL) instead.
The question is of course is, do I now keep the 997 or sell on post repair? Answers on the back of a £50 note to my address please.
The question is of course is, do I now keep the 997 or sell on post repair? Answers on the back of a £50 note to my address please.
2005/55 997 C2S
51,000 miles
Burns a lot of oil (~2L every 1000 miles) but runs fine otherwise. It's been looked at and there's nothing untoward about the engine, it just likes a drink.
Update after selling the car. Misfire started at 59k miles. Continued heavy oil consumption, in ~10,000 miles it went through just under two gallons. Not including a service. The oil indicator was flashing below the minimum on the display far more than it should have been. Never had the oil light come on though.
I would say I got shot before something expensive happened. Consider my engine another knock against Porsche reliability.
51,000 miles
Burns a lot of oil (~2L every 1000 miles) but runs fine otherwise. It's been looked at and there's nothing untoward about the engine, it just likes a drink.
Update after selling the car. Misfire started at 59k miles. Continued heavy oil consumption, in ~10,000 miles it went through just under two gallons. Not including a service. The oil indicator was flashing below the minimum on the display far more than it should have been. Never had the oil light come on though.
I would say I got shot before something expensive happened. Consider my engine another knock against Porsche reliability.
Edited by sebhaque on Thursday 22 May 20:32
996 Targa C2 3.6 manual, late 2002, 83,000 miles.
Bought it in June, 6 weeks later the engine went phut.
Took it to Brookspeed in Southampton who diagnosed IMS bearing failure and sent it to Hartech for an engine rebuild, currently underway with various partly-worn bits being replaced in the hope that I'll get a few years of reliable motoring out of it for the (substantial) rebuild investment.
Bought it in June, 6 weeks later the engine went phut.
Took it to Brookspeed in Southampton who diagnosed IMS bearing failure and sent it to Hartech for an engine rebuild, currently underway with various partly-worn bits being replaced in the hope that I'll get a few years of reliable motoring out of it for the (substantial) rebuild investment.
I have been considering buying a 996 as its been a while since anythind rear engined has graced the drive . After reading this thread I know I'm not as brave or rich as you boys. I think I will stick to the old "44 turbo", makes me smile when I drive it not worry about new rattles I can hear. Thanks for making my mind up and good luck with those engines.
997 C2S 2005 purchased at Porsche Guildford last Sept.
4k miles in a year and oil level has not changed and no drips in the garage.
Warranty repair on gear box and front suspension in the first couple of months of ownership and doesn't need a service for another year. Nothing noted on MOT the other week either.
In comparison my E46 M3 cost £3.5k a year in the last 3 years on maintenance.
4k miles in a year and oil level has not changed and no drips in the garage.
Warranty repair on gear box and front suspension in the first couple of months of ownership and doesn't need a service for another year. Nothing noted on MOT the other week either.
In comparison my E46 M3 cost £3.5k a year in the last 3 years on maintenance.
98 996 c2 60,000 miles when sold, one RMS when clutch replaced @50,000
2001 boxster 2.7 no evidence of either a failure or RMS change 105,000 mls
1997 boxster 2.5, 87,000 mls no evidence if engine or RMS
2000 996 c2 90,000 miles, no failures and no evidence of RMS change, has a full OPC history from new and had extended warranty so could well have been done. The engine is as dry as a bone
Seems to me the troubled cars gave trouble within the first 40,000 miles though there are probably exceptions, makes me sleep better!
2001 boxster 2.7 no evidence of either a failure or RMS change 105,000 mls
1997 boxster 2.5, 87,000 mls no evidence if engine or RMS
2000 996 c2 90,000 miles, no failures and no evidence of RMS change, has a full OPC history from new and had extended warranty so could well have been done. The engine is as dry as a bone
Seems to me the troubled cars gave trouble within the first 40,000 miles though there are probably exceptions, makes me sleep better!
1998 C2 Cab
Engine blew at 18k - my dad owned it at that point and I am unsure what it was but I don't believe it was IMS.
Porsche replaced the engine for free despite it not even being within warranty at that point (yes, shock horror indeed!)
Since then I have now done just over 103k on the clock with no IMS issues and we have had it in the family since 1999.
Had the RMS done at about 85k because the garage figured they might as well get it sorted whilst the clutch was being done.
Should have had the IMS looked at at this point but didn't....read forums, panicked and then got that done too about 4 weeks ago although I wasn't experiencing any problems.
All in all since I bought the car off my old man with 53k on it I have had to replace the water pump, clutch, master-cylinder and the exhaust...that's pretty much it I think apart from the usual stuff like tyres and accidentally buggering up the window mechanism when unwinding frozen windows!
Never had to put any oil in between services and the water has only been slightly topped up once since new.
Used every day as a daily driver covering over a 100 miles a day. Drove it all round France with no bother apart from getting dirty looks off the locals for not driving a renault and also having english plates.
.....now let's compare with an MGF I had previously (from new and looked after "carefully")
2 new radiators
5 head gasket repairs
3 new stereos
engine mounts breaking twice
suspension snapping twice on potholes
Spent the majority of the first year back in the dealership being fixed
Sold to me at the time as "a sports car" then after breaking it several times the same sales guy said to me "look, you cant drive it like a sports car and have to be more careful with it!"
This is in the space of 4 years and 25k miles.
It never ceases to amaze me when I see some 2nd hand car sales magazine or car programme say buy an MGF its a bargain for summer yet then hear bad press about the 996. Sure my 996 isn't a looker and it's a bit of a cruiser but it costs me the same to insure as my old CTR, less to tax, less to maintain, less for tyres, doesn't look like a chavved out breadvan and if the bugger goes bang I can probably buy another one for 10k.
Bargain!
Engine blew at 18k - my dad owned it at that point and I am unsure what it was but I don't believe it was IMS.
Porsche replaced the engine for free despite it not even being within warranty at that point (yes, shock horror indeed!)
Since then I have now done just over 103k on the clock with no IMS issues and we have had it in the family since 1999.
Had the RMS done at about 85k because the garage figured they might as well get it sorted whilst the clutch was being done.
Should have had the IMS looked at at this point but didn't....read forums, panicked and then got that done too about 4 weeks ago although I wasn't experiencing any problems.
All in all since I bought the car off my old man with 53k on it I have had to replace the water pump, clutch, master-cylinder and the exhaust...that's pretty much it I think apart from the usual stuff like tyres and accidentally buggering up the window mechanism when unwinding frozen windows!
Never had to put any oil in between services and the water has only been slightly topped up once since new.
Used every day as a daily driver covering over a 100 miles a day. Drove it all round France with no bother apart from getting dirty looks off the locals for not driving a renault and also having english plates.
.....now let's compare with an MGF I had previously (from new and looked after "carefully")
2 new radiators
5 head gasket repairs
3 new stereos
engine mounts breaking twice
suspension snapping twice on potholes
Spent the majority of the first year back in the dealership being fixed
Sold to me at the time as "a sports car" then after breaking it several times the same sales guy said to me "look, you cant drive it like a sports car and have to be more careful with it!"
This is in the space of 4 years and 25k miles.
It never ceases to amaze me when I see some 2nd hand car sales magazine or car programme say buy an MGF its a bargain for summer yet then hear bad press about the 996. Sure my 996 isn't a looker and it's a bit of a cruiser but it costs me the same to insure as my old CTR, less to tax, less to maintain, less for tyres, doesn't look like a chavved out breadvan and if the bugger goes bang I can probably buy another one for 10k.
Bargain!
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