Intermediate Shaft Warning
Discussion
Unlikely - we did once hear a strange noise while under a running car on a ramp and found a split bearing cage but all the balls still running OK - the noise was the ball bearings knocking into each other instead of being kept apart by the cage. We managed to change the bearing with the engine in situ (and have since made some special tools to assist doing this in future as preventative maintenance).
However once it has failed and you can hear a noise - don't drive about in it until it is inspected - or it will just end up costing much more.
This week we have rebuilt one engine in which the car has been driven around with a broken intermediate shaft bearing and had destroyed the shaft, housing, tensioner arms, etc and also a piece of debris got stuck in between the crankshaft sprocket teeth and bent them (goodbye crankshaft - over £2K extra!). It could become a big problem as the bearings will soon no longer be in stock.
But then we have also stripped another engine (that owner was reliably informed had an intermediate shaft bearing damaged diagnosed form swarf in the oil pan) that was clearly a crankshaft shell (as the swarf it had bronze bits in it) and has wrecked the crankshaft etc. This one caused by a blocked oil pick up strainer and overheated crankshaft shells that had melted the white metal.
So it is not it seems even easy to diagnose and always expensive to rebuild once it has gone too far - and not easy to get to in time except with preventative maintenance.
Baz
However once it has failed and you can hear a noise - don't drive about in it until it is inspected - or it will just end up costing much more.
This week we have rebuilt one engine in which the car has been driven around with a broken intermediate shaft bearing and had destroyed the shaft, housing, tensioner arms, etc and also a piece of debris got stuck in between the crankshaft sprocket teeth and bent them (goodbye crankshaft - over £2K extra!). It could become a big problem as the bearings will soon no longer be in stock.
But then we have also stripped another engine (that owner was reliably informed had an intermediate shaft bearing damaged diagnosed form swarf in the oil pan) that was clearly a crankshaft shell (as the swarf it had bronze bits in it) and has wrecked the crankshaft etc. This one caused by a blocked oil pick up strainer and overheated crankshaft shells that had melted the white metal.
So it is not it seems even easy to diagnose and always expensive to rebuild once it has gone too far - and not easy to get to in time except with preventative maintenance.
Baz
IMHO the bearings come with seals on each side that prevent the free flow of oil in and out of the bearing. They also trap the small bits of metal that gradually wear off bearings and form a kind of grinding paste that wears the bearing - or the oil and the bearing overheat as a result of the work it does and there being no oil flow. The spindle is also very fragile.
We correct these items when we rebuild engines or replace bearings.
I think the seals must be there to protect against dust during storage before assembly as I can think of no other reason for the seals - something that also is found in gearbox bearings - many of which similarly fail IMHO for the same reasons.
Baz
We correct these items when we rebuild engines or replace bearings.
I think the seals must be there to protect against dust during storage before assembly as I can think of no other reason for the seals - something that also is found in gearbox bearings - many of which similarly fail IMHO for the same reasons.
Baz
Baz
Are you suggesting that it is a good idea to change the bearing before it fails and is there an upgraded bearing that is stronger for want of a better word, furthermore, this can be done with the engine in but box out?
If so I will arrange to get this done forthwith as prevention is better than cure and I can enjoy the car more.
Are you suggesting that it is a good idea to change the bearing before it fails and is there an upgraded bearing that is stronger for want of a better word, furthermore, this can be done with the engine in but box out?
If so I will arrange to get this done forthwith as prevention is better than cure and I can enjoy the car more.
You can do this with the gearbox out using some tools we have made to support the shaft, and we charge £200 to do this +vat (if added to a clutch job or RMS at fixed cost - see menu), £500 + Vat (manual gearbox as a job on its own), £800 + Vat (tiptronic as a job on its own).
Failures are however still rare and so as long as there are no other relevant noises or signs of a failure or iminent failure - we do not classify this as something that needs doing unless you happen to be already paying for other work that gets you near the job and therefore at a reduced cost - although we do discount the cost to our Lifetime Maintenance Plan customers by 50% by way of a compromise - if they want it done seperately.
There have been several re-designs of this part, different bearings, housings and spindles and we will soon run out of bearings ourselves for the eariest type and will need to redesign some other parts to utilise a different bearing (spares of the original are not available).
There is not room to change the bearing for a better one but of course we can improve the cooling and oil delivery by removing the seal and strengthen the spindle by simply making it bigger and changing the seal location to keep the shaft larger in diameter (something that could easily have been done originally).
I think I would have originally fitted a plain bearing and drilled a minute hole in the bottom of the other end of the shaft so the oil pump (which is run off it) delivered a constant stream of oil along the shaft to lubricate the bearing (and we may well try a plain bearing one day - we may indeed have to come up with something else eventually).
We intend to build a dyno facility and then build a track car to test out our modifications under greater loads - next year - to prove or disprove their suitability - and are therefore into this job of fixing these engines for the long term.
Baz
Failures are however still rare and so as long as there are no other relevant noises or signs of a failure or iminent failure - we do not classify this as something that needs doing unless you happen to be already paying for other work that gets you near the job and therefore at a reduced cost - although we do discount the cost to our Lifetime Maintenance Plan customers by 50% by way of a compromise - if they want it done seperately.
There have been several re-designs of this part, different bearings, housings and spindles and we will soon run out of bearings ourselves for the eariest type and will need to redesign some other parts to utilise a different bearing (spares of the original are not available).
There is not room to change the bearing for a better one but of course we can improve the cooling and oil delivery by removing the seal and strengthen the spindle by simply making it bigger and changing the seal location to keep the shaft larger in diameter (something that could easily have been done originally).
I think I would have originally fitted a plain bearing and drilled a minute hole in the bottom of the other end of the shaft so the oil pump (which is run off it) delivered a constant stream of oil along the shaft to lubricate the bearing (and we may well try a plain bearing one day - we may indeed have to come up with something else eventually).
We intend to build a dyno facility and then build a track car to test out our modifications under greater loads - next year - to prove or disprove their suitability - and are therefore into this job of fixing these engines for the long term.
Baz
hartech said:
You can do this with the gearbox out using some tools we have made to support the shaft, and we charge £200 to do this +vat (if added to a clutch job or RMS at fixed cost - see menu), £500 + Vat (manual gearbox as a job on its own), £800 + Vat (tiptronic as a job on its own).
Failures are however still rare and so as long as there are no other relevant noises or signs of a failure or iminent failure - we do not classify this as something that needs doing unless you happen to be already paying for other work that gets you near the job and therefore at a reduced cost - although we do discount the cost to our Lifetime Maintenance Plan customers by 50% by way of a compromise - if they want it done seperately.
There have been several re-designs of this part, different bearings, housings and spindles and we will soon run out of bearings ourselves for the eariest type and will need to redesign some other parts to utilise a different bearing (spares of the original are not available).
There is not room to change the bearing for a better one but of course we can improve the cooling and oil delivery by removing the seal and strengthen the spindle by simply making it bigger and changing the seal location to keep the shaft larger in diameter (something that could easily have been done originally).
I think I would have originally fitted a plain bearing and drilled a minute hole in the bottom of the other end of the shaft so the oil pump (which is run off it) delivered a constant stream of oil along the shaft to lubricate the bearing (and we may well try a plain bearing one day - we may indeed have to come up with something else eventually).
We intend to build a dyno facility and then build a track car to test out our modifications under greater loads - next year - to prove or disprove their suitability - and are therefore into this job of fixing these engines for the long term.
Baz
Thank you Failures are however still rare and so as long as there are no other relevant noises or signs of a failure or iminent failure - we do not classify this as something that needs doing unless you happen to be already paying for other work that gets you near the job and therefore at a reduced cost - although we do discount the cost to our Lifetime Maintenance Plan customers by 50% by way of a compromise - if they want it done seperately.
There have been several re-designs of this part, different bearings, housings and spindles and we will soon run out of bearings ourselves for the eariest type and will need to redesign some other parts to utilise a different bearing (spares of the original are not available).
There is not room to change the bearing for a better one but of course we can improve the cooling and oil delivery by removing the seal and strengthen the spindle by simply making it bigger and changing the seal location to keep the shaft larger in diameter (something that could easily have been done originally).
I think I would have originally fitted a plain bearing and drilled a minute hole in the bottom of the other end of the shaft so the oil pump (which is run off it) delivered a constant stream of oil along the shaft to lubricate the bearing (and we may well try a plain bearing one day - we may indeed have to come up with something else eventually).
We intend to build a dyno facility and then build a track car to test out our modifications under greater loads - next year - to prove or disprove their suitability - and are therefore into this job of fixing these engines for the long term.
Baz
A resurrected theme after over a year since I last posted - since then we have increased rebuilds to more than 1/week - and we have seen so many damaged IMS shafts and bearings, so many crankshaft failures etc - it is impossible to remember exactly which one you are referring to - sorry.
The failures are changing slightly with slightly less IMS failures and more crankshaft bearing failures, while cracked liners and heads continue at much the same pace.
There seem to be two main crankshaft failures - (1) the white metal on the shells disintegrates in pockets until one reaches the outside when the oil pressure to that bearing and the adjoining main bearing fails through lack of local oil pressure, (2) a piece of debris from the internal silicon sealant overspill finally coming loose and blocking an oilway.
IMS bearings seen to settle down after 80K and are "run in" enough to work OK for a lot longer.
Some chains snap through localised quality failures (particularly the later upgrade engine specs).
All bores distort oval in time and eventually I guess will fail through cracking or seizures caused by excessive blow by - a shame as the problem is so easily rectified by fitting our restraining rings and could have been a permanent mod from new.
Cracked heads seem quite random although they do seem to crack soonest on vehicles driven hard before a slow warm up.
Despite gradual development over many previous models - the 944's still had a problem with the No 2 big end and eventually head gaskets, The 944 S1's and 2's with cams/chains and valve springs, the 3.2 carerra's with piston rings, the 964's with head sealing (and general electrics), 968's with cam chains and pinion bearings and the 993 seems the best overall and the 996's and Boxsters, have these relatively infrequent engine problems that cost little different to fix but perhaps arrive a little sooner and a little more often - but the cars are relativley less expensive, more comfortable and much quicker - so in my view - getting on a protective maintenance plan (like ours) or simply taking your chances if and when the problem hits you - is not such a big issue for such a brilliant car.
It is perhaps the fact that so few places can rebuild them (and others only offer a risky used engine or an expensive new one) that has changed owners perception of the problem - because our prices for fixing these problems (on or off our Maintenance Plan) are little more than owners previously encountered with older more reverred models when lack of the Internet failed to raise the problems to such a wide audience.
I think prices now could justify preventative maintenance engine rebuilds - providing they correct issues like the oval bores (as we do) but not if they don't, while getting on our Maintenance plan is a no brainer - as it lasts the life of the car and they will all eventually need something fixing inside, which hardly anyone else has the ability to perform.
Baz
The failures are changing slightly with slightly less IMS failures and more crankshaft bearing failures, while cracked liners and heads continue at much the same pace.
There seem to be two main crankshaft failures - (1) the white metal on the shells disintegrates in pockets until one reaches the outside when the oil pressure to that bearing and the adjoining main bearing fails through lack of local oil pressure, (2) a piece of debris from the internal silicon sealant overspill finally coming loose and blocking an oilway.
IMS bearings seen to settle down after 80K and are "run in" enough to work OK for a lot longer.
Some chains snap through localised quality failures (particularly the later upgrade engine specs).
All bores distort oval in time and eventually I guess will fail through cracking or seizures caused by excessive blow by - a shame as the problem is so easily rectified by fitting our restraining rings and could have been a permanent mod from new.
Cracked heads seem quite random although they do seem to crack soonest on vehicles driven hard before a slow warm up.
Despite gradual development over many previous models - the 944's still had a problem with the No 2 big end and eventually head gaskets, The 944 S1's and 2's with cams/chains and valve springs, the 3.2 carerra's with piston rings, the 964's with head sealing (and general electrics), 968's with cam chains and pinion bearings and the 993 seems the best overall and the 996's and Boxsters, have these relatively infrequent engine problems that cost little different to fix but perhaps arrive a little sooner and a little more often - but the cars are relativley less expensive, more comfortable and much quicker - so in my view - getting on a protective maintenance plan (like ours) or simply taking your chances if and when the problem hits you - is not such a big issue for such a brilliant car.
It is perhaps the fact that so few places can rebuild them (and others only offer a risky used engine or an expensive new one) that has changed owners perception of the problem - because our prices for fixing these problems (on or off our Maintenance Plan) are little more than owners previously encountered with older more reverred models when lack of the Internet failed to raise the problems to such a wide audience.
I think prices now could justify preventative maintenance engine rebuilds - providing they correct issues like the oval bores (as we do) but not if they don't, while getting on our Maintenance plan is a no brainer - as it lasts the life of the car and they will all eventually need something fixing inside, which hardly anyone else has the ability to perform.
Baz
Brilliant informative stuff as always Baz..
Makes me wonder if I should keep the Hartech maintenance plan on my 993 current though
Seriously though , it's great to see some of the M96 gremlins being smoothed out.
What a lot of car you can get for your money now , and I'd be quite happy to run one so long as it was on your plan.
As a matter of interest , if one were to get all the weak bits sorted with you before any failures , would it be a very expensive option?
Say for example, crankshaft work ,better (open lubed) IMS, cylinder rings , new chains ... Or would you have to do a lot more work (like valve guides etc) to justify the re-build in the first place?
Makes me wonder if I should keep the Hartech maintenance plan on my 993 current though
Seriously though , it's great to see some of the M96 gremlins being smoothed out.
What a lot of car you can get for your money now , and I'd be quite happy to run one so long as it was on your plan.
As a matter of interest , if one were to get all the weak bits sorted with you before any failures , would it be a very expensive option?
Say for example, crankshaft work ,better (open lubed) IMS, cylinder rings , new chains ... Or would you have to do a lot more work (like valve guides etc) to justify the re-build in the first place?
My intermediate shaft was replaced on my 996TT.
It started to make a clicking sound at idle. Seemed to disappear under revs (but then it is hard to hear the sound over the engine).
Once replaced, no clicking/rattling sound.
Do a search on You Tube. There are a couple of videos where a dodgy IS can be heard.
Of course, the 996TT is a different engine that the NA 996, so it could be a completely different sound.
It started to make a clicking sound at idle. Seemed to disappear under revs (but then it is hard to hear the sound over the engine).
Once replaced, no clicking/rattling sound.
Do a search on You Tube. There are a couple of videos where a dodgy IS can be heard.
Of course, the 996TT is a different engine that the NA 996, so it could be a completely different sound.
Excellent information as always Baz.
Having recently bought a 3.2 SSE with a genuine 69,000 miles on the clock it was interesting to see what was worn when the engine was stripped. Bores were perfect with original honing marks present. The main and big ends still showed their original Porsche material yet the rings were worn to 1.7mm. I gather 1mm is the maximum. Oil pump although stripped and cleaned still had a tight spot in it. As it is going to be a road legal race car I bit the bullet and bought new factory barrels and pistons etc as well as replacing all the other bits and pieces, timing chains, valve guides etc. etc.
Having recently bought a 3.2 SSE with a genuine 69,000 miles on the clock it was interesting to see what was worn when the engine was stripped. Bores were perfect with original honing marks present. The main and big ends still showed their original Porsche material yet the rings were worn to 1.7mm. I gather 1mm is the maximum. Oil pump although stripped and cleaned still had a tight spot in it. As it is going to be a road legal race car I bit the bullet and bought new factory barrels and pistons etc as well as replacing all the other bits and pieces, timing chains, valve guides etc. etc.
graeme36s said:
Excellent information as always Baz.
Having recently bought a 3.2 SSE with a genuine 69,000 miles on the clock it was interesting to see what was worn when the engine was stripped. Bores were perfect with original honing marks present. The main and big ends still showed their original Porsche material yet the rings were worn to 1.7mm. I gather 1mm is the maximum. Oil pump although stripped and cleaned still had a tight spot in it. As it is going to be a road legal race car I bit the bullet and bought new factory barrels and pistons etc as well as replacing all the other bits and pieces, timing chains, valve guides etc. etc.
OUt of interest, why did you change the B&P?Having recently bought a 3.2 SSE with a genuine 69,000 miles on the clock it was interesting to see what was worn when the engine was stripped. Bores were perfect with original honing marks present. The main and big ends still showed their original Porsche material yet the rings were worn to 1.7mm. I gather 1mm is the maximum. Oil pump although stripped and cleaned still had a tight spot in it. As it is going to be a road legal race car I bit the bullet and bought new factory barrels and pistons etc as well as replacing all the other bits and pieces, timing chains, valve guides etc. etc.
Bert
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