Crankshaft not centered
05-13-2010, 11:10 PM
#16
Drifting
I would think that that if the crank was true but off center then it would not vary with rotation. It should be the same offset even with rotation. So if a dial indicator is on the crank and it is showing a variation, then the crank. or at least the flange must be bent or out of true.
05-13-2010, 11:47 PM
#17
Rennlist Member
"So in one position it goes in and in the other there is a gap and does not."
Bent crank from the flywheel\clutch mishap. If it were not concentric it would be tight on the same side when rotated. Bent would be 'tight' moves with the crank.
Bent crank from the flywheel\clutch mishap. If it were not concentric it would be tight on the same side when rotated. Bent would be 'tight' moves with the crank.
05-14-2010, 12:22 AM
#19
Parts Specialist
Rennlist Member
Rennlist Member
you have to talk to the pro's
sadly the outlook is not good but like I said if you can get the real experts on it, they may know a way to diagnos it further and pinpoint the problem and if the problem falls into the right bucket, they may know a fix... its a longshot but you have nothing to loose
sadly the outlook is not good but like I said if you can get the real experts on it, they may know a way to diagnos it further and pinpoint the problem and if the problem falls into the right bucket, they may know a fix... its a longshot but you have nothing to loose
05-14-2010, 01:24 AM
#22
Parts Specialist
Rennlist Member
Rennlist Member
tough call... it must be diagnosed as running it could lead to a dangerous and more costly repair (ie the flywheel rattles around in the bell housing.... unlikely but the vibration is telling you something more than your RMS isnt sealing)
05-14-2010, 02:01 AM
#23
Wouldn't be the first time a crank cracked/broke and hangs in there still running/rotating. 4 bolt mains have done it and I think I recall the 996 is around 6 or more bolts. Doesn't look good with the out of line crank.
Looking at the present doom the first thing I'd think is compair plain jane engine replacement to radical add ons to correct the problem. Could be a good chance to make a race engine.
Looking at the present doom the first thing I'd think is compair plain jane engine replacement to radical add ons to correct the problem. Could be a good chance to make a race engine.
05-14-2010, 03:35 AM
#24
It's a "Paint To Sample" car, painted in Riviera Blue. It was a color Porsche used sparingly in the '90s on the 993 model line of the 911. There are a couple RLers with Riviera 993 cabs
.
And a question for the OP.
What happened to your clutch to cause such catastrophic failure? I don't believe this is very common. Did the parts simply fail or was there any driver involvement here?
And again, this really sucks.
Phil
05-14-2010, 05:03 AM
#25
Rennlist Member
This sounds like something which happened on PorscheClubGreatBritian (PCGB)... Here's the link http://www.porscheclubgbforum.com/tm...&mpage=1&key=&. You need to subscribe, but here's the text...
ORIGINAL: SidewaysSteve
Recently I bought a little Boxster 2.7, cracking clean car with full Porsche and Indy Service history on a 2000 W Plate with 122,000 miles on her.
Car looked to be the perfect Porsche, with its history, loads of receipts for parts, tyres etc etc and more importantly a new clutch and flywheel fitted back in July and with only 3,000 miles on her up until now.
On the test drive she was fine, no nasty noises, smoke, etc etc however what I didnt do (despite having bnought plenty of cars and repaired even more) was give it a proper hard drive on th etest i.e. take it right up the revs fully.
I reved her out fairly well but changed around 5000 rpm as it seemed smooth enough and was pulling well.
Drove home the 420 miles back to Scotland and in the morning went out and gave my new toy a good clean and polish, however there were some oil spots on my driveway....
To cut a long story short the recently fitted dual mass flywheel had failed and at revs above 5,500 rpm was causing some severe engine vibration which in turn was causing the RMS to leak and was making the clutch cover contact the gearbox housing and had scraped the metal inside it.
Over the weekend just past I stripped down the back of the car, cleaned up all the mess and fitted a nice new LUK dual mass flywheel and a new RMS.
Once refitted and back on all 4 wheels I took her for a spin, once again above 5,500 rpm I had heavy vibrations so clearly something was still imbalanced.
I stripped the box back off again and cranked the engine by had with the clutch removed and only the flywheel fitted to discover it was wobbling like a wheel with a buckle and therefore causing the vibrations at certain rpm's.
How was this possible ??? brand new flywheel and its wobbling about !!
Well, its possible because with the flywheel removed and by rotating the crank you can clearly see the flywheel end of the crank "orbiting" within the RMS which I may add was now damaged again due to the movement of the crank.
I have not had a chance to investigate further yet HOWEVER it would appear that the crankshaft itself has somehow managed to warp or bend at the flywheel end.
Piecing together data I have via receipts and from speaking to M96 engine failure specialists, at this point we have come to the following conclusion.
The clutch/flywheel fitted in July were done as we think the car had suffered a DMF/Clutch failure. We think that the failure of the original DMF has caused such an imbalance that it has warped or possibly fractured the crankshaft.
The new DMF was then fitted in July and the car was indeed running however at high rpm the distorted crank was causing the whole rotating assembly to be out of balance which in turn was worsening the situation and eventually caused the NEW DMF to fail too.
When the July DMF failed it added to the already imbalanced vibrations which has distroted/cracked the crankshaft even more.
The end result here is that the engine will need to be pulled and stripped to determine what parts are damaged and what parts are salvagable.
Hopefully due to catching this issue early on I may be lucky and manage to rebuild the engine using a new crank and bearings.
The moral of this story is that when you replace the clutch on one of these engines I would STRONGLY suggest paying the extra £400 ish quid for a NEW dual mass flywheel, as if one fails you could be looking at seriious bills for repair.
I am in the lucky position that I can do all this work myself, therefore cost to me is only that of parts. If a dealership or any other garage would have taken on the work I have done you would easily be into thousands of pounds for labour.
I will be pulling the engine fully and stripping it on Saturday so I will take pictures and keep you all informed of the findings.
For now though, im so glad I decided to buy a Porsche ....... LOL
Recently I bought a little Boxster 2.7, cracking clean car with full Porsche and Indy Service history on a 2000 W Plate with 122,000 miles on her.
Car looked to be the perfect Porsche, with its history, loads of receipts for parts, tyres etc etc and more importantly a new clutch and flywheel fitted back in July and with only 3,000 miles on her up until now.
On the test drive she was fine, no nasty noises, smoke, etc etc however what I didnt do (despite having bnought plenty of cars and repaired even more) was give it a proper hard drive on th etest i.e. take it right up the revs fully.
I reved her out fairly well but changed around 5000 rpm as it seemed smooth enough and was pulling well.
Drove home the 420 miles back to Scotland and in the morning went out and gave my new toy a good clean and polish, however there were some oil spots on my driveway....
To cut a long story short the recently fitted dual mass flywheel had failed and at revs above 5,500 rpm was causing some severe engine vibration which in turn was causing the RMS to leak and was making the clutch cover contact the gearbox housing and had scraped the metal inside it.
Over the weekend just past I stripped down the back of the car, cleaned up all the mess and fitted a nice new LUK dual mass flywheel and a new RMS.
Once refitted and back on all 4 wheels I took her for a spin, once again above 5,500 rpm I had heavy vibrations so clearly something was still imbalanced.
I stripped the box back off again and cranked the engine by had with the clutch removed and only the flywheel fitted to discover it was wobbling like a wheel with a buckle and therefore causing the vibrations at certain rpm's.
How was this possible ??? brand new flywheel and its wobbling about !!
Well, its possible because with the flywheel removed and by rotating the crank you can clearly see the flywheel end of the crank "orbiting" within the RMS which I may add was now damaged again due to the movement of the crank.
I have not had a chance to investigate further yet HOWEVER it would appear that the crankshaft itself has somehow managed to warp or bend at the flywheel end.
Piecing together data I have via receipts and from speaking to M96 engine failure specialists, at this point we have come to the following conclusion.
The clutch/flywheel fitted in July were done as we think the car had suffered a DMF/Clutch failure. We think that the failure of the original DMF has caused such an imbalance that it has warped or possibly fractured the crankshaft.
The new DMF was then fitted in July and the car was indeed running however at high rpm the distorted crank was causing the whole rotating assembly to be out of balance which in turn was worsening the situation and eventually caused the NEW DMF to fail too.
When the July DMF failed it added to the already imbalanced vibrations which has distroted/cracked the crankshaft even more.
The end result here is that the engine will need to be pulled and stripped to determine what parts are damaged and what parts are salvagable.
Hopefully due to catching this issue early on I may be lucky and manage to rebuild the engine using a new crank and bearings.
The moral of this story is that when you replace the clutch on one of these engines I would STRONGLY suggest paying the extra £400 ish quid for a NEW dual mass flywheel, as if one fails you could be looking at seriious bills for repair.
I am in the lucky position that I can do all this work myself, therefore cost to me is only that of parts. If a dealership or any other garage would have taken on the work I have done you would easily be into thousands of pounds for labour.
I will be pulling the engine fully and stripping it on Saturday so I will take pictures and keep you all informed of the findings.
For now though, im so glad I decided to buy a Porsche ....... LOL
ORIGINAL: SidewaysSteve
haha cheeky barsteward :P Ill have you know my tools are well oiled LOL
Seriously though, cheers for the comments I wanted to keep this all posted to show what CAN happen if you dont look after things, Its costing me money but hopefully it will save others from needing to spend loads on a replacement engine.
All this is down to a Dual mass flywheel failing. Why it failed I am unsure but my bets would be that it was not replaced at the time of doing a clutch as is recommended by most people who know about them !
Heres a brief report I wrote up. Ill be doing a full engineers report type document when i get time for those who are interested which will include some calculations of forces acting on the end of the crank etc etc but I am far to busy with work and getting this back on the road to do it at the moment !
What happened is if you look in the lower pictures of the flywheel end of the crank still sitting in the cradle you can actually see its bent just in at the bearing.
The process of self destruction was as follows:
1) Dual mass flywheel failed causing imbalance in the end of the crank.
2) Last main beaing began to wear excessively causing more imbalance and movement in end of crank.
3) Imbalance at high RPM caused crank flex leading to the flywheel/clutch assembly contacting the gearbox bellhousing.
4) Bellhousing contact "kinked" the end of the crankshaft (forces in excess of 1800 Nm acting upon the end of the crank)
5) Clutch was damaged and started to slip
6) Previous Owner took car to garage regarding the clutch issue and strange vibrations at certain RPM
7) Garage incorrectly renewed the flywheel which was found to be faulty and replaced the clutch but DID NOT check for damage to the crankshaft
8) Car ran not too bad for 6 months being driven normally but due to the now kinked crank the bearing wear in the last main bearing got worse and worse.
9) Eventually the main bearing nearest the flywheel failed completely due to the huge forces acting upon it through crank imbalance and the next in bearing began to wear.
10) The now huge amounts of crank movement damaged the new DMF and was allowing the assembly to wiggle about contacting parts of the gearbox bellhousing again whilst all the time wearing the end and second main bearings more and more to the point of complete destruction.
The bottom liine is that the bearings have lost their white metal coating and completely destoyed the already badly damaged crankshaft.
It really is amazing to think that this engine was actually running sweet below 5500 rpm with no nasty noises !!!!!
The bits of spring that you see are from the RMS which was also badly damaged due to the movement in the crankshaft.
Luckily the filter in the oil pump has done its job incredibly well and NO debris has entered the pump or been moved round the rest of the engine meaining that the engine is repairable due to catching this in time !
It does look like a spun bearing at first glance but you can tell its not due to a few things,
Firstly the crank is clearly bent at one end, theres no doubt about that ! theres 0.43mm of runout on it which is crazy !
Secondly the locating tabs on the bearing shells are all intact and not damaged indicatiing that the bearings have not spun in the cradle.
Thirdly the cradle is completely undamaged somehow and there are not any signs of damage to the cups which hold the bearing shells.
haha cheeky barsteward :P Ill have you know my tools are well oiled LOL
Seriously though, cheers for the comments I wanted to keep this all posted to show what CAN happen if you dont look after things, Its costing me money but hopefully it will save others from needing to spend loads on a replacement engine.
All this is down to a Dual mass flywheel failing. Why it failed I am unsure but my bets would be that it was not replaced at the time of doing a clutch as is recommended by most people who know about them !
Heres a brief report I wrote up. Ill be doing a full engineers report type document when i get time for those who are interested which will include some calculations of forces acting on the end of the crank etc etc but I am far to busy with work and getting this back on the road to do it at the moment !
What happened is if you look in the lower pictures of the flywheel end of the crank still sitting in the cradle you can actually see its bent just in at the bearing.
The process of self destruction was as follows:
1) Dual mass flywheel failed causing imbalance in the end of the crank.
2) Last main beaing began to wear excessively causing more imbalance and movement in end of crank.
3) Imbalance at high RPM caused crank flex leading to the flywheel/clutch assembly contacting the gearbox bellhousing.
4) Bellhousing contact "kinked" the end of the crankshaft (forces in excess of 1800 Nm acting upon the end of the crank)
5) Clutch was damaged and started to slip
6) Previous Owner took car to garage regarding the clutch issue and strange vibrations at certain RPM
7) Garage incorrectly renewed the flywheel which was found to be faulty and replaced the clutch but DID NOT check for damage to the crankshaft
8) Car ran not too bad for 6 months being driven normally but due to the now kinked crank the bearing wear in the last main bearing got worse and worse.
9) Eventually the main bearing nearest the flywheel failed completely due to the huge forces acting upon it through crank imbalance and the next in bearing began to wear.
10) The now huge amounts of crank movement damaged the new DMF and was allowing the assembly to wiggle about contacting parts of the gearbox bellhousing again whilst all the time wearing the end and second main bearings more and more to the point of complete destruction.
The bottom liine is that the bearings have lost their white metal coating and completely destoyed the already badly damaged crankshaft.
It really is amazing to think that this engine was actually running sweet below 5500 rpm with no nasty noises !!!!!
The bits of spring that you see are from the RMS which was also badly damaged due to the movement in the crankshaft.
Luckily the filter in the oil pump has done its job incredibly well and NO debris has entered the pump or been moved round the rest of the engine meaining that the engine is repairable due to catching this in time !
It does look like a spun bearing at first glance but you can tell its not due to a few things,
Firstly the crank is clearly bent at one end, theres no doubt about that ! theres 0.43mm of runout on it which is crazy !
Secondly the locating tabs on the bearing shells are all intact and not damaged indicatiing that the bearings have not spun in the cradle.
Thirdly the cradle is completely undamaged somehow and there are not any signs of damage to the cups which hold the bearing shells.
05-14-2010, 08:58 AM
#26
Burning Brakes
I received the email from the original poster. I'll reply here.
First, a question: Was this engine suffering from RMS leakage prior to being disassembled? From the pics it looks to have been mostly dry with only some residual oil being noted from the old seal extraction.
This issue of the crank not being centered is actually due to the entire crankshaft carrier not being centered within the block halves. We have developed a method of repairing this with the engine disassembled, but there is no cure for it if still together except a full tear down.
If taken to a facility filled with "rule followers" and book readers the only solution would be to replace the engine, or pull it apart and have us do the required work to re-center, which would cost more than a new engine.
If I was in this position and the RMS was not leaking prior to disassembly I'd apply the newest Porsche RMS, put it back together and hope like hell it didn't leak. The new seals are very durable and they do conform to changes in the positioning of the seal flange more than the originals. I'd say if it wasn't leaking before you have a good chance that it won't leak again with the new seal, but it is a risk that could lead to wasted dollars for reassembly.... or it could lead to a lot of savings.
According to the "book" you are screwed, but in reality you might not be. Are you a gambling man?
First, a question: Was this engine suffering from RMS leakage prior to being disassembled? From the pics it looks to have been mostly dry with only some residual oil being noted from the old seal extraction.
This issue of the crank not being centered is actually due to the entire crankshaft carrier not being centered within the block halves. We have developed a method of repairing this with the engine disassembled, but there is no cure for it if still together except a full tear down.
If taken to a facility filled with "rule followers" and book readers the only solution would be to replace the engine, or pull it apart and have us do the required work to re-center, which would cost more than a new engine.
If I was in this position and the RMS was not leaking prior to disassembly I'd apply the newest Porsche RMS, put it back together and hope like hell it didn't leak. The new seals are very durable and they do conform to changes in the positioning of the seal flange more than the originals. I'd say if it wasn't leaking before you have a good chance that it won't leak again with the new seal, but it is a risk that could lead to wasted dollars for reassembly.... or it could lead to a lot of savings.
According to the "book" you are screwed, but in reality you might not be. Are you a gambling man?
05-14-2010, 12:43 PM
#28
Well, Sorry but Jake obviously didn't read this whole thread nor get all the details in the one email he was sent.
If the crank was off center, the GO - NO GO tool would not be able to GO at all, at any position of crank rotation. If you put a dial indicator on the end of that crank and rotate it, you'd have the exact answer. No more questions. There is also the issue of the vibration.
I like my idea better than Jake's. There's no way I'd put this back together without checking (especially since we already know the crank is damaged by the use of the G -NG tool) the run out of the crank and just hope for a miracle.
Phil
If the crank was off center, the GO - NO GO tool would not be able to GO at all, at any position of crank rotation. If you put a dial indicator on the end of that crank and rotate it, you'd have the exact answer. No more questions. There is also the issue of the vibration.
I like my idea better than Jake's. There's no way I'd put this back together without checking (especially since we already know the crank is damaged by the use of the G -NG tool) the run out of the crank and just hope for a miracle.
Phil
05-14-2010, 12:48 PM
#29
Parts Specialist
Rennlist Member
Rennlist Member
OH dont get me wrong I agree you have to find whats causing the vibration - Jake only pointed out what one could do about the RMS issue and did not address the vibration at all...
my first reply said you have to rotate the crank and see (measure) whats going on AND I also said IF the crank is bent it could frac and be a bigger repair... So NO the diagnostics are not over... but if that end checks out, the statement Jake made is valid (but ONLY then)
my first reply said you have to rotate the crank and see (measure) whats going on AND I also said IF the crank is bent it could frac and be a bigger repair... So NO the diagnostics are not over... but if that end checks out, the statement Jake made is valid (but ONLY then)
05-14-2010, 02:30 PM
#30
Burning Brakes
I made my post based on the email he sent me..
Was a vibration there before? You do know that new clutch components and flywheels are marginally balanced, right?
If the issue wasn't there before I'd doubt the vibration is the crank.. A crank is hard as hell and tough as nails, it would be hard to damage, BUT i have seen installers put flywheels back in place that were not seated properly to the crankshaft, causing a vibration.
Was a vibration there before? You do know that new clutch components and flywheels are marginally balanced, right?
If the issue wasn't there before I'd doubt the vibration is the crank.. A crank is hard as hell and tough as nails, it would be hard to damage, BUT i have seen installers put flywheels back in place that were not seated properly to the crankshaft, causing a vibration.