Crank thrust bearing issues
08-25-2005, 01:05 PM
#46
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Royal purple makes a great racing oil in the correct viscosities also. Stephan would any of this help. I guess the problem is not the film strength but the dry start up condition?
08-25-2005, 01:34 PM
#47
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You guys are playing with fire if you're still using 0w40. It may not be the overriding cause if this particular bearing failure, but it does contribute, especially on startup and at high temps. You will also find, that many other bearings and guides will begin to wear prematurely on all vehicles that run hot oil temps and use the 0w40. Been rebuilding motors for longer than many of you could ride a bike and seen the damage caused by too low of viscosity oil more times than I can remember. Stay away from this latest oil fad and use what works and properly protects. Take 2 bearings and dip 1 in a 0w40 oil and 1 in 15w40 and let them sit overnight. Which one has more oil film on it? The one that does will be better protected at startup. This is basic common sense and Porsche is dead wrong with their 0w40 fill in hot clomates. At least Mercedes corrected ther mistakes and no longer uses the 0w40. I wonder how much longer til Porsche also makes the change.
For those that don't care about long term wear, then stick with the 0w40 and enjoy the unmeasurable economy improvement.
For those that don't care about long term wear, then stick with the 0w40 and enjoy the unmeasurable economy improvement.
08-25-2005, 02:39 PM
#48
If we are talking about the same issue, the problem and the cause is known by Porsche.
It has nothing to do with extra Cams, although as stated the extra loading must exert itself on these parts, nor does it have anything to do with Clutch operation, or too much or too little end play in the Crankshaft. The end play of the Crankshaft should be typical, and this dimension is not unique to this engine. Whatever you set this to in a 911 or 993 engine, will work here. This dimension is very typical in all types of engines.
A photo of the other half of the bearing shell will confirm that we are discussing the same issue. The one photo of the 1 half of the rear Main shell shows the cause and the result. If the other 1/2 is the same or similar, then we are talking about the same issue, and the cause is known and I beleive limited to certain engines in a certain time period of production.
The extra end play you are measuring is a result of the problem, not the cause. This fault appears to be limited to this engine by production date. This fault can and does happen in all types of engines when the fault is the same. It is not a design fault with this engine.
This is basic stuff, and will always be evident upon proper inspection and measuring. The evidence is shown on the bearing shell in the photo, and typical of this fault.
One of the great things about Porsche, is the high level of production quality. Typically, Porsche engines are just assemblied, and never inspected or measured. Becaue of the high level of quality, assembly without your typical "blueprinting" checks will suffice. The problem is that if you don't check you will never know. When problems arise like this one, the cause gets overlooked.
Most of the time the machining is done "outside" the repair shop. This is how faults like this get overlooked. The machine shop gets the parts, but doesn't check anything as they never see the parts showing the problem. The assembler does not have the experience with other engines of lower quality where these sort of issues arise, does not see and understand the cause and fault, and does not tell the machine shop to check. I cannot say this happens everywhere, but in the case here, it appears to be the case, as the photo shows the typical tell tale signs of this common fault. When building up Chevrolet, Ford or Mopar engines as race engines, where the quality control is way less, this sort of problem is very common and requires the proper attention to detail.
It has nothing to do with extra Cams, although as stated the extra loading must exert itself on these parts, nor does it have anything to do with Clutch operation, or too much or too little end play in the Crankshaft. The end play of the Crankshaft should be typical, and this dimension is not unique to this engine. Whatever you set this to in a 911 or 993 engine, will work here. This dimension is very typical in all types of engines.
A photo of the other half of the bearing shell will confirm that we are discussing the same issue. The one photo of the 1 half of the rear Main shell shows the cause and the result. If the other 1/2 is the same or similar, then we are talking about the same issue, and the cause is known and I beleive limited to certain engines in a certain time period of production.
The extra end play you are measuring is a result of the problem, not the cause. This fault appears to be limited to this engine by production date. This fault can and does happen in all types of engines when the fault is the same. It is not a design fault with this engine.
This is basic stuff, and will always be evident upon proper inspection and measuring. The evidence is shown on the bearing shell in the photo, and typical of this fault.
One of the great things about Porsche, is the high level of production quality. Typically, Porsche engines are just assemblied, and never inspected or measured. Becaue of the high level of quality, assembly without your typical "blueprinting" checks will suffice. The problem is that if you don't check you will never know. When problems arise like this one, the cause gets overlooked.
Most of the time the machining is done "outside" the repair shop. This is how faults like this get overlooked. The machine shop gets the parts, but doesn't check anything as they never see the parts showing the problem. The assembler does not have the experience with other engines of lower quality where these sort of issues arise, does not see and understand the cause and fault, and does not tell the machine shop to check. I cannot say this happens everywhere, but in the case here, it appears to be the case, as the photo shows the typical tell tale signs of this common fault. When building up Chevrolet, Ford or Mopar engines as race engines, where the quality control is way less, this sort of problem is very common and requires the proper attention to detail.
08-25-2005, 02:50 PM
#49
Rennlist Lifetime Member
According to the spec for the thrust end play these motors were all on the low side of the measurement. All excessive number wise compared to the older motors.
08-25-2005, 03:25 PM
#50
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Originally Posted by m42racer
A photo of the other half of the bearing shell will confirm that we are discussing the same issue. The one photo of the 1 half of the rear Main shell shows the cause and the result. If the other 1/2 is the same or similar, then we are talking about the same issue, and the cause is known and I beleive limited to certain engines in a certain time period of production.
08-25-2005, 05:09 PM
#51
This problem shows up as something else to. Porsche warranties this and issued a special tool to the agencies to check this problem. When it appears, its warranted.
I think its unfair to splatter all over here a problem that they will take care of. Those that know what to look for can see from the photo the tell tale signs.
If you really need to know if your engine is OK, then have Porsche inspect the engine at the next service.
Knowledge is a tool, and in a competitive business, is what makes some businesses better than others. As there are businesses on here that make money doing this kind of work, it seems unfair to those that know, to "give it up" to those that appear not to.
I think its unfair to splatter all over here a problem that they will take care of. Those that know what to look for can see from the photo the tell tale signs.
If you really need to know if your engine is OK, then have Porsche inspect the engine at the next service.
Knowledge is a tool, and in a competitive business, is what makes some businesses better than others. As there are businesses on here that make money doing this kind of work, it seems unfair to those that know, to "give it up" to those that appear not to.
08-25-2005, 05:28 PM
#52
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Stephen,
Do you ever see any strange wear in the next bearing in sequence? If not are you assuming the crank is actually flexing enough that the next bearing is never impacted?? I can't believe ANY oil could protect the motor from that kind of wear.. excluding something like a 90 wt :-)
Those pics are SCARY... may never sell my 930TT :-).. for a 996...
Ed
Do you ever see any strange wear in the next bearing in sequence? If not are you assuming the crank is actually flexing enough that the next bearing is never impacted?? I can't believe ANY oil could protect the motor from that kind of wear.. excluding something like a 90 wt :-)
Those pics are SCARY... may never sell my 930TT :-).. for a 996...
Ed
08-25-2005, 06:56 PM
#53
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"As there are businesses on here that make money doing this kind of work, it seems unfair to those that know, to "give it up" to those that appear not to."
Simon, who would you recomend all the customers and shop owners that participate on this forum call? Neil Harvey... Look, this is a new low for you. I'd think that with your intellect and money you could invite Neil to this thread and have him lay it out and educate those that don't know. Come on, why add fuel to the fire.
Damn, this ranks as someone saying, I know a doctor that can cure you, but your to stupid to know..
Even if Stephen or Chris Cervelli have there opinion and do not know that Porsche might have a TSP on this issue. This is a technical forum Rennlist is about sharing and offering advice. It is the advice that they shop owner give, that makes people decide where and who they should take there cars in for service.
You might as well have said, Damn Stephen and Chris and all that posted, you don't know... And I'm not telling you.. That should have been your first reply. What you have created is a situation where alot of folks are running to the dealers or regional Porsche tech guys and are asking for answers.
Simon, who would you recomend all the customers and shop owners that participate on this forum call? Neil Harvey... Look, this is a new low for you. I'd think that with your intellect and money you could invite Neil to this thread and have him lay it out and educate those that don't know. Come on, why add fuel to the fire.
Damn, this ranks as someone saying, I know a doctor that can cure you, but your to stupid to know..
Even if Stephen or Chris Cervelli have there opinion and do not know that Porsche might have a TSP on this issue. This is a technical forum Rennlist is about sharing and offering advice. It is the advice that they shop owner give, that makes people decide where and who they should take there cars in for service.
You might as well have said, Damn Stephen and Chris and all that posted, you don't know... And I'm not telling you.. That should have been your first reply. What you have created is a situation where alot of folks are running to the dealers or regional Porsche tech guys and are asking for answers.
08-25-2005, 07:25 PM
#54
Rennlist Lifetime Member
I just checked all my current TSBs and nothing for the TT/GT2 or GT3. I also called Peter Smith and had him looked up any issues as described through the Porsche's database system. Nothing came up. He went through the most current back to 4 years. Nothing showed up.
I do know that there is a TSB for the Boxster and 996. There is a tool for those that check roundness of the case and straightness of the crank. That is an old TSB and not the same case nor crank.
I have several contacts like this through Porsche so if there is a TSB that is being missed through PCNA let me know the number. We can look it up and find it. As it stands there is nothing officially through the dealers or PCNA. Peter said he still has heard nothing on this at all.
I do know that there is a TSB for the Boxster and 996. There is a tool for those that check roundness of the case and straightness of the crank. That is an old TSB and not the same case nor crank.
I have several contacts like this through Porsche so if there is a TSB that is being missed through PCNA let me know the number. We can look it up and find it. As it stands there is nothing officially through the dealers or PCNA. Peter said he still has heard nothing on this at all.
08-25-2005, 09:05 PM
#55
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So if I asked a porsche dealer to inspect everything on my car before it ran out of warrranty and then this appears I could sue them citing your comments. Is that right. Please. It might be percieved that if folks like me could have known to ask for a specific "check" but did not know and then have to pay for a premature engine overhaul when you could have shed some light, I imagine your list of fellow enthusiast friends will have gotten a bit shorter. I agree with Kevin. Sometimes knowledge does not translate into credability.
08-25-2005, 10:51 PM
#56
I am sorry if I offended any one here. That was not my intention.
Clearly the bearing shows signs of wear, and it was stated that the Crank has excessive backlash, so there must be some problem here. And this problem has been seen on several engines by the Stephen, looking at the number of rear main bearings he showed. It has also been seen by others.
As I stated earlier, but not very clear, and as Stephen has just posted, there is a known fault with the other engine models. My post said, if we are talking about "the same issue" Porsche know about this.
Kevin, com'on man, read my postings.
As for my non disclosure of any information, its as simple as this. There are TSB's about "the same issue" with the other engines. Understood by all here. There obviously is nothing as Stephen stated about the 996TT. No TSB on this engine. Do you have to wait for a TSB from Porsche to inspect, understand the problem and fix it? All of the information is in front of you. You have bearings, an open engine, Engine Case, Crankshaft etc, all in parts. Repairing does not have to be left to Porsche, unless you want it done under warranty. We as private business can do this ourselves, can we not? Especially if they (Porsche) have yet to consider this a concern. What do you do if you don't fix the problem? Replace the bearings and hope the problem goes away. No, you get in there and fix it. And when you do, this becomes a trick in your bag that you do business with.
My intention here was never to incit any concern amoungst owners. If I did, I apologize. I can now see how it could have. I am sorry for this. Was not intented. As for owners on this forum, you can only have repaired under warranty that which Porsche deems required. If there is no TSB issued from Porsche, they obviously do not consider this to be a problem.
Clearly the bearing shows signs of wear, and it was stated that the Crank has excessive backlash, so there must be some problem here. And this problem has been seen on several engines by the Stephen, looking at the number of rear main bearings he showed. It has also been seen by others.
As I stated earlier, but not very clear, and as Stephen has just posted, there is a known fault with the other engine models. My post said, if we are talking about "the same issue" Porsche know about this.
Kevin, com'on man, read my postings.
As for my non disclosure of any information, its as simple as this. There are TSB's about "the same issue" with the other engines. Understood by all here. There obviously is nothing as Stephen stated about the 996TT. No TSB on this engine. Do you have to wait for a TSB from Porsche to inspect, understand the problem and fix it? All of the information is in front of you. You have bearings, an open engine, Engine Case, Crankshaft etc, all in parts. Repairing does not have to be left to Porsche, unless you want it done under warranty. We as private business can do this ourselves, can we not? Especially if they (Porsche) have yet to consider this a concern. What do you do if you don't fix the problem? Replace the bearings and hope the problem goes away. No, you get in there and fix it. And when you do, this becomes a trick in your bag that you do business with.
My intention here was never to incit any concern amoungst owners. If I did, I apologize. I can now see how it could have. I am sorry for this. Was not intented. As for owners on this forum, you can only have repaired under warranty that which Porsche deems required. If there is no TSB issued from Porsche, they obviously do not consider this to be a problem.
08-25-2005, 11:13 PM
#57
Rennlist Lifetime Member
Simon,
Fixing the backlash issue is simple. Any of us that do more than just bolt on parts knows what the fix is, but the caveat here is why? Why does Porsche have the spec on paper in measurement when all the other motors have a much smaller spec? See for me if I fix it and there is honestly a reason why it should be that loose, even if it means that it wears the thrust then why? If I fix that, what are they trying to do and what might be affected.
Is this a cover for something else? The one unknown here is this is the first motor of its type that will see mileage. Similar to the 959, yes. But not exactly the same. So we have the issue of little long term data and certainly if we fix the thrust what other effect might that have in regards to the other components, like the lay shaft and valvetrain. I am not so certain that the spec is that way for the drag of the valve train. Which is HUGE.
All simplistic questions, but so few even build these the data is spotty at best. Chris and I talked about this issue. Peter and I have talk about this issue, Bruce, Tom and so on. I want to know why the piece of gum is in the dam wall before I remove it. It isn’t that we are hoping it goes away, we know it will not. The issue is why have they said this spec is ok? Like I said, I want to understand why. I sure as hell can fix the lash issue and bring it in. That is the easy part. BTW the spec that you mention being the same issue, is not. I have checked for that and all the cases are ok. The same issue does not apply to these cases nor crank.
Fixing the backlash issue is simple. Any of us that do more than just bolt on parts knows what the fix is, but the caveat here is why? Why does Porsche have the spec on paper in measurement when all the other motors have a much smaller spec? See for me if I fix it and there is honestly a reason why it should be that loose, even if it means that it wears the thrust then why? If I fix that, what are they trying to do and what might be affected.
Is this a cover for something else? The one unknown here is this is the first motor of its type that will see mileage. Similar to the 959, yes. But not exactly the same. So we have the issue of little long term data and certainly if we fix the thrust what other effect might that have in regards to the other components, like the lay shaft and valvetrain. I am not so certain that the spec is that way for the drag of the valve train. Which is HUGE.
All simplistic questions, but so few even build these the data is spotty at best. Chris and I talked about this issue. Peter and I have talk about this issue, Bruce, Tom and so on. I want to know why the piece of gum is in the dam wall before I remove it. It isn’t that we are hoping it goes away, we know it will not. The issue is why have they said this spec is ok? Like I said, I want to understand why. I sure as hell can fix the lash issue and bring it in. That is the easy part. BTW the spec that you mention being the same issue, is not. I have checked for that and all the cases are ok. The same issue does not apply to these cases nor crank.
08-26-2005, 01:27 AM
#59
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Thread Starter
An old hot rod trick was to file a small amount of the bearing away where marked. This allowed increased oil to flow fron the center of the bearing to the thrust surface. Is this the big secret fiix?
08-26-2005, 09:31 AM
#60
Rennlist Lifetime Member
No, you would need to repair the crank to correct the thrust spec issue. The crank in all the motors were straight with in spec run out. If we look at what the 964 cranks were like (really bad) they still did not leave marks like this. All the thrust wear in time on the older motors, just not typically until they are higher mileage like 60,70K+