Cautionary Tale of Oil Leak (timing cover)
04-26-2019, 10:45 AM
#46
Drifting
So after reading through the latest posts on this subject, it seems more and more like this leak problem is being caused by factory over-torqued aluminum timing cover bolt(s) that have sheared as a result. And/or can the leak also occur if the bolts are over-torqued but not to the point of actually shearing the bolt heads?
Is this it, bolts, or does this timing cover leak sometimes occur from other causes as well (warped cover or something like that)??
Just trying to get clarification on the root cause(s).
Is this it, bolts, or does this timing cover leak sometimes occur from other causes as well (warped cover or something like that)??
Just trying to get clarification on the root cause(s).
04-26-2019, 05:40 PM
#47
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The short story: I don't think we'll ever have a definitive root cause.
We can speculate on the functional failure and guess at the root cause. The former is what you 'see' and the latter is always a business process failure of some sort.
It is my opinion that the bolts are not 'over-torqued' but that the material used in the fasteners is not as-designed. This may be pedantic but there's a material difference (no pun intended.)
Based upon what I saw and from talking with two techs on several occasions, it is the bolts snapping that enable the cover leak. This is my opinion based upon the observations I have. My observations are data that is a small N in the overall data set.
It is possible that the 'fastener issue' might result in warped covers. I don't think this likely. The cover is pretty beefy. Obviously, so is the block.
It is possible that initially-warped covers might leak regardless of any 'fastener issue.' But, given that this failure, when it occurs, does not occur immediately after in-service suggests that it is not the functional failure.
So, I believe that the functional failure (the failure in the field) is the bolts are snapping due to heat cycle fatigue (expansion and contraction.)
Further I speculate that the likely root cause, in order of what I think most likely to least likely, is;
- materials substitution due to "bean counters" late in the design cycle, or perhaps coincident with manufacturing start, with no engineering sign-off. In other words, the torque procedure was originally based upon a fastener made of Alloy X and bean counters substituted Alloy Y and didn't tell anyone in Engineering and/or no one cared what Engineering said about the Alloy Change.
- some sort of human error on torque specification or procedure (at any point from design to data entry) that wound its way into the factory system and workshop manual documentation:
* it could have been a design error, but design reviews are supposed to find this type of error. And so is pre-production testing. So, not likely in my book.
* the torque procedure might have been 'fat-fingered' between design and the manufacturing system.
I would place my bet on the root cause occurring after pre-production testing and before production-start. I tend to place blame too easily on bean counters so I give human error equal odds.
FWIW...
We can speculate on the functional failure and guess at the root cause. The former is what you 'see' and the latter is always a business process failure of some sort.
So after reading through the latest posts on this subject, it seems more and more like this leak problem is being caused by factory over-torqued aluminum timing cover bolt(s) that have sheared as a result. And/or can the leak also occur if the bolts are over-torqued but not to the point of actually shearing the bolt heads?
Is this it, bolts, or does this timing cover leak sometimes occur from other causes as well (warped cover or something like that)??
It is possible that the 'fastener issue' might result in warped covers. I don't think this likely. The cover is pretty beefy. Obviously, so is the block.
It is possible that initially-warped covers might leak regardless of any 'fastener issue.' But, given that this failure, when it occurs, does not occur immediately after in-service suggests that it is not the functional failure.
So, I believe that the functional failure (the failure in the field) is the bolts are snapping due to heat cycle fatigue (expansion and contraction.)
Further I speculate that the likely root cause, in order of what I think most likely to least likely, is;
- materials substitution due to "bean counters" late in the design cycle, or perhaps coincident with manufacturing start, with no engineering sign-off. In other words, the torque procedure was originally based upon a fastener made of Alloy X and bean counters substituted Alloy Y and didn't tell anyone in Engineering and/or no one cared what Engineering said about the Alloy Change.
- some sort of human error on torque specification or procedure (at any point from design to data entry) that wound its way into the factory system and workshop manual documentation:
* it could have been a design error, but design reviews are supposed to find this type of error. And so is pre-production testing. So, not likely in my book.
* the torque procedure might have been 'fat-fingered' between design and the manufacturing system.
I would place my bet on the root cause occurring after pre-production testing and before production-start. I tend to place blame too easily on bean counters so I give human error equal odds.
FWIW...
04-26-2019, 08:33 PM
#48
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One more thing...
As far as the techs I talked to know, Porsche has not updated anything from the bolts to the torque procedure. So, if the repair is done 'by the book' it seems likely that the cover leak failure will happen again.
If you have this repair performed, you should talk to your tech and determine what they are doing to prevent, or make less likely, the same failure mode after the repair.
As far as the techs I talked to know, Porsche has not updated anything from the bolts to the torque procedure. So, if the repair is done 'by the book' it seems likely that the cover leak failure will happen again.
If you have this repair performed, you should talk to your tech and determine what they are doing to prevent, or make less likely, the same failure mode after the repair.
04-27-2019, 02:21 AM
#50
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This is an engine-out repair. This is the reason the 'fastener issue' is so vexing. If done by the book, it's outside of the wherewithal of the vast majority of DIYers and, I suspect, many Indy shops. I also doubt that it can be completed without the PISIW laptop due to needing to bleed the engine cooling system and recharge the A/C (I don't know for sure though.) I have to imagine that it's a $5k service, at least, when done out of warrenty.
All because of over-stressed $0.20 aluminum bolts.
04-29-2019, 12:28 AM
#52
Has anyone here asked if there have been any oil leaks AFTER the issue was resolved? I'm curious about that. The repairs are done by hand in a shop and not on a production floor. So I ask again, anyone have problems after this issue was fixed?
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FJP29 (08-25-2021)
04-29-2019, 05:18 PM
#53
Drifting
The short story: I don't think we'll ever have a definitive root cause.
We can speculate on the functional failure and guess at the root cause. The former is what you 'see' and the latter is always a business process failure of some sort.
It is my opinion that the bolts are not 'over-torqued' but that the material used in the fasteners is not as-designed. This may be pedantic but there's a material difference (no pun intended.)
Based upon what I saw and from talking with two techs on several occasions, it is the bolts snapping that enable the cover leak. This is my opinion based upon the observations I have. My observations are data that is a small N in the overall data set.
It is possible that the 'fastener issue' might result in warped covers. I don't think this likely. The cover is pretty beefy. Obviously, so is the block.
It is possible that initially-warped covers might leak regardless of any 'fastener issue.' But, given that this failure, when it occurs, does not occur immediately after in-service suggests that it is not the functional failure.
So, I believe that the functional failure (the failure in the field) is the bolts are snapping due to heat cycle fatigue (expansion and contraction.)
Further I speculate that the likely root cause, in order of what I think most likely to least likely, is;
- materials substitution due to "bean counters" late in the design cycle, or perhaps coincident with manufacturing start, with no engineering sign-off. In other words, the torque procedure was originally based upon a fastener made of Alloy X and bean counters substituted Alloy Y and didn't tell anyone in Engineering and/or no one cared what Engineering said about the Alloy Change.
- some sort of human error on torque specification or procedure (at any point from design to data entry) that wound its way into the factory system and workshop manual documentation:
* it could have been a design error, but design reviews are supposed to find this type of error. And so is pre-production testing. So, not likely in my book.
* the torque procedure might have been 'fat-fingered' between design and the manufacturing system.
I would place my bet on the root cause occurring after pre-production testing and before production-start. I tend to place blame too easily on bean counters so I give human error equal odds.
FWIW...
We can speculate on the functional failure and guess at the root cause. The former is what you 'see' and the latter is always a business process failure of some sort.
It is my opinion that the bolts are not 'over-torqued' but that the material used in the fasteners is not as-designed. This may be pedantic but there's a material difference (no pun intended.)
Based upon what I saw and from talking with two techs on several occasions, it is the bolts snapping that enable the cover leak. This is my opinion based upon the observations I have. My observations are data that is a small N in the overall data set.
It is possible that the 'fastener issue' might result in warped covers. I don't think this likely. The cover is pretty beefy. Obviously, so is the block.
It is possible that initially-warped covers might leak regardless of any 'fastener issue.' But, given that this failure, when it occurs, does not occur immediately after in-service suggests that it is not the functional failure.
So, I believe that the functional failure (the failure in the field) is the bolts are snapping due to heat cycle fatigue (expansion and contraction.)
Further I speculate that the likely root cause, in order of what I think most likely to least likely, is;
- materials substitution due to "bean counters" late in the design cycle, or perhaps coincident with manufacturing start, with no engineering sign-off. In other words, the torque procedure was originally based upon a fastener made of Alloy X and bean counters substituted Alloy Y and didn't tell anyone in Engineering and/or no one cared what Engineering said about the Alloy Change.
- some sort of human error on torque specification or procedure (at any point from design to data entry) that wound its way into the factory system and workshop manual documentation:
* it could have been a design error, but design reviews are supposed to find this type of error. And so is pre-production testing. So, not likely in my book.
* the torque procedure might have been 'fat-fingered' between design and the manufacturing system.
I would place my bet on the root cause occurring after pre-production testing and before production-start. I tend to place blame too easily on bean counters so I give human error equal odds.
FWIW...
04-30-2019, 04:57 PM
#54
The timing chain cover uses dozens of these Torx socket head bolts. They are made of aluminum. The bolt above snapped in half right at the gasket. It was the bolt snapping that caused the leak.
Apparently these M6 bolts are a torque-to-a-low-spec (8 n-m) plus 90-degrees. The standard torque for a steel grade 8 M6 is 10 n-m. That 90 degrees probably puts it at 15+ n-m which is breaking territory for a steel bolt.
Aluminum bolts. Stupid. Stupid. Stupid.
When this job is done out-of-warranty by an Indy, I'm gonna bet good-ole-fashioned steel bolts go in.
Apparently these M6 bolts are a torque-to-a-low-spec (8 n-m) plus 90-degrees. The standard torque for a steel grade 8 M6 is 10 n-m. That 90 degrees probably puts it at 15+ n-m which is breaking territory for a steel bolt.
Aluminum bolts. Stupid. Stupid. Stupid.
When this job is done out-of-warranty by an Indy, I'm gonna bet good-ole-fashioned steel bolts go in.
8 Nm is only 5.9 lb ft. My understanding is the torque then degree rotation is supposed to be more accurate than a
simple torque to spec. procedure. I also read that it is intended to stretch the bolts and that they CANNOT be reused.
Once stretched, they do not retain elasticity and return to their original length.
During a recent oil change I was shown the 'dreaded oil seepage' and have an appointment set up to have it addressed.
I have been told the procedure has been modified and the new torque spec. is now 4 Nm - or 2.95 lb. ft. plus the 90
degrees.
I sincerely that puts an end to timing chain cover oil seepage issues.
BTW, why does this have to be an 'engine out' procedure? That seems like a lot of extra work just to get to the front on the engine!
How about removing the front bumper & radiator and leaving the engine in the vehicle?
I looked in the Macan Service & Repair Manual and it makes no mention of pulling the engine. It does note there are two (2) timing
chain covers - upper and lower. I would wonder where the Torx bolt failures are occurring - limited to one cover or the other or
randomly between both covers?
Curiously, in the procedure for the upper cover it mentions removing the guide tube for the oil dipstick(?!?!). What dipstick?
There are six (6) bolts for the upper cover and thirteen (13) bolts for the lower cover. Further it states the tightening for the bolts in the
upper cover to be 9 Nm and the lower cover to be 8 Nm and the final tightening for the lower cover (ONLY) to be +45 degrees.
Further, the manual states the lower cover must be replaced. Perhaps this is a plastic part that cannot be reused?
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tagnew (09-26-2020)
05-03-2019, 02:04 AM
#55
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8 Nm is only 5.9 lb ft. My understanding is the torque then degree rotation is supposed to be more accurate than a
simple torque to spec. procedure. I also read that it is intended to stretch the bolts and that they CANNOT be reused. Once stretched, they do not retain elasticity and return to their original length.
simple torque to spec. procedure. I also read that it is intended to stretch the bolts and that they CANNOT be reused. Once stretched, they do not retain elasticity and return to their original length.
Two seperate but closely related concepts. Torque-and-angle is a more accurate way to achieve a specific clamping force. Torque is effectively a measure of friction. But, clamping force can be calculated based upon rotation of the fastener. Clamping force at any specific torque will vary based upon the condition of the fastener, hole, and any lubrication or 'gunk' on the threads. Thus, torque is a 'guess' at clamping force.
Torque-to-yield is - as you write - where the fastener is stretched beyond it's elasticity. It's necessary when - for whatever reason - the smallest possible faster is to be used.
Torque-to-yield fasteners are usually fastened with torque-and-angle. But just because torque-and-angle is used it doesn't necessarily follow that the fastener is torque-to-yield.
If 'the book' says replace the bolt, then it's safe to assume torque-to-yield.
During a recent oil change I was shown the 'dreaded oil seepage' and have an appointment set up to have it addressed.
I have been told the procedure has been modified and the new torque spec. is now 4 Nm - or 2.95 lb. ft. plus the 90
degrees.
I have been told the procedure has been modified and the new torque spec. is now 4 Nm - or 2.95 lb. ft. plus the 90
degrees.
BTW, why does this have to be an 'engine out' procedure? That seems like a lot of extra work just to get to the front on the engine!
How about removing the front bumper & radiator and leaving the engine in the vehicle?
How about removing the front bumper & radiator and leaving the engine in the vehicle?
FWIW.
I looked in the Macan Service & Repair Manual and it makes no mention of pulling the engine. It does note there are two (2) timing
chain covers - upper and lower.
chain covers - upper and lower.
Preliminary work
Step 1. Remove engine -> WM 100119 Removing and installing engine.
That's from the factory tech info.
I would wonder where the Torx bolt failures are occurring - limited to one cover or the other or
randomly between both covers?
randomly between both covers?
Curiously, in the procedure for the upper cover it mentions removing the guide tube for the oil dipstick(?!?!). What dipstick?
There are six (6) bolts for the upper cover and thirteen (13) bolts for the lower cover. Further it states the tightening for the bolts in the
upper cover to be 9 Nm and the lower cover to be 8 Nm and the final tightening for the lower cover (ONLY) to be +45 degrees.
upper cover to be 9 Nm and the lower cover to be 8 Nm and the final tightening for the lower cover (ONLY) to be +45 degrees.
My version of 1533119 is about 6 months old. So, recent revisions are likely.
Further, the manual states the lower cover must be replaced. Perhaps this is a plastic part that cannot be reused?
05-04-2019, 03:58 PM
#56
In the version of the workshop manual I have it makes no mention of removing the engine in the preliminary work section for 153319.
In mine, the only preliminary item listed for the upper cover is to remove the engine cover. For the lower cover, the preliminary steps listed
include: drain engine oil, remove belt tensioner and remove pulley.
And step 6 for the lower housing cover states: "Install new chain housing cover." with the bold face in the document.
Curious.
Your copy is newer than mine, so it appears they've modified the procedure.
Thx for your updates Mr. Worf.
In mine, the only preliminary item listed for the upper cover is to remove the engine cover. For the lower cover, the preliminary steps listed
include: drain engine oil, remove belt tensioner and remove pulley.
And step 6 for the lower housing cover states: "Install new chain housing cover." with the bold face in the document.
Curious.
Your copy is newer than mine, so it appears they've modified the procedure.
Thx for your updates Mr. Worf.
05-05-2019, 11:24 AM
#57
Racer
If I were to get this repair done out of warranty, do you think techs would be able to do it without removing the engine? What kind of cost are we looking at if that is the case?
05-06-2019, 02:35 PM
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It's almost 'too interesting' that the procedure for the chain cover would change so drastically. There's also a couple of things you reported about your version that are drastically different from mine. You reported:
- two covers
- 19 bolts
Whereas in what I have, it looks like one big cover and 30 bolts.
I think the WM#'s for procedure X are the same across models but the contents are different based upon the specific model/engine type.
Is it possible that you are looking at the procedure for the 4-cylinder engine? (Edit: Mine's for the "Turbo" so there's yet a third possibility.)
My first thought was that you were looking at the drive belt procedure, not the chain cover procedure. But, with the WM numbers the same, I don't think this is the case.
I'd *guess* that this is a >$5k repair out of warranty. As far as motor-in or motor-out, as I wrote above, there was a post early in this thread, contents since deleted, that some techs had figured out a way to do the repair with the motor in.
Any thoughtful tech, without 'constraints from on-high' would look to conduct the repair in the least time-consuming manner consistent with a quality outcome. This, modulo whatever special tools or capabilities are required. For example, if PIWIS is required for the engine-out procedure and the (Indy) shop doesn't have a PIWIS, then they are going to attempt the engine-in procedure. On the other hand, if there are no constraints, I would expect that the Tech/Shop would probably desire to minimize labor as long as doing so doesn't risk a failure of the repair under warranty.
Bottom line, I don't know which way is quicker. I would need to do this repair task both ways before being certain which way is 'better.' I would expect the same from any shop/tech. It's not clear to me which way is actually faster.
Motor removal is often perceived as a daunting task with the thought that any way to do the job with the motor in place is better. This is not always true. But, it takes experience to know.
Last, I sure hope whatever repairs are being conducted last for many years. I picked-up our Macan on Saturday. All's well so far. I do not want to pay to have it done again in a few years and I really, really don't want to have to do this repair myself.
- two covers
- 19 bolts
Whereas in what I have, it looks like one big cover and 30 bolts.
I think the WM#'s for procedure X are the same across models but the contents are different based upon the specific model/engine type.
Is it possible that you are looking at the procedure for the 4-cylinder engine? (Edit: Mine's for the "Turbo" so there's yet a third possibility.)
My first thought was that you were looking at the drive belt procedure, not the chain cover procedure. But, with the WM numbers the same, I don't think this is the case.
Any thoughtful tech, without 'constraints from on-high' would look to conduct the repair in the least time-consuming manner consistent with a quality outcome. This, modulo whatever special tools or capabilities are required. For example, if PIWIS is required for the engine-out procedure and the (Indy) shop doesn't have a PIWIS, then they are going to attempt the engine-in procedure. On the other hand, if there are no constraints, I would expect that the Tech/Shop would probably desire to minimize labor as long as doing so doesn't risk a failure of the repair under warranty.
Bottom line, I don't know which way is quicker. I would need to do this repair task both ways before being certain which way is 'better.' I would expect the same from any shop/tech. It's not clear to me which way is actually faster.
Motor removal is often perceived as a daunting task with the thought that any way to do the job with the motor in place is better. This is not always true. But, it takes experience to know.
Last, I sure hope whatever repairs are being conducted last for many years. I picked-up our Macan on Saturday. All's well so far. I do not want to pay to have it done again in a few years and I really, really don't want to have to do this repair myself.
05-06-2019, 06:43 PM
#59
I've been following this thread as well as posts of a similar manner on another board. They all have the same thing in common:
1. Snapped bolts.......
That's it. The bolts being used. There's a lot of discussion about how much torque and then turn 90 degrees more..... The fact still remains Porsche is using an incorrect grade of aluminum bolt. Possibly the wrong bolt all together. What is being used is too brittle and as we're finding out, they're snapping in half. So, what are the alternatives?
Porsche could issue a TSB stating to use a different bolt. Maybe steel. Maybe a higher torque grade aluminum bolt, if a type exists. We ourselves could request the Porsche dealership to use a bolt of a higher caliber. But, if it's not OEM, they'd beg off and refuse unless you know someone there and get it done as a favor.
Aside from that, I believe this is going to keep happening even after a fix. Eventually, I see Porsche pushing back on this and refuse the work unless it's "severe enough". I hope I'm wrong as a first-time Porsche owner.
1. Snapped bolts.......
That's it. The bolts being used. There's a lot of discussion about how much torque and then turn 90 degrees more..... The fact still remains Porsche is using an incorrect grade of aluminum bolt. Possibly the wrong bolt all together. What is being used is too brittle and as we're finding out, they're snapping in half. So, what are the alternatives?
Porsche could issue a TSB stating to use a different bolt. Maybe steel. Maybe a higher torque grade aluminum bolt, if a type exists. We ourselves could request the Porsche dealership to use a bolt of a higher caliber. But, if it's not OEM, they'd beg off and refuse unless you know someone there and get it done as a favor.
Aside from that, I believe this is going to keep happening even after a fix. Eventually, I see Porsche pushing back on this and refuse the work unless it's "severe enough". I hope I'm wrong as a first-time Porsche owner.
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russw (08-09-2020)
05-06-2019, 09:24 PM
#60
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I've been following this thread as well as posts of a similar manner on another board. They all have the same thing in common:
1. Snapped bolts.......
That's it. The bolts being used. There's a lot of discussion about how much torque and then turn 90 degrees more..... The fact still remains Porsche is using an incorrect grade of aluminum bolt. Possibly the wrong bolt all together. What is being used is too brittle and as we're finding out, they're snapping in half. So, what are the alternatives?
Porsche could issue a TSB stating to use a different bolt. Maybe steel. Maybe a higher torque grade aluminum bolt, if a type exists. We ourselves could request the Porsche dealership to use a bolt of a higher caliber. But, if it's not OEM, they'd beg off and refuse unless you know someone there and get it done as a favor.
Aside from that, I believe this is going to keep happening even after a fix. Eventually, I see Porsche pushing back on this and refuse the work unless it's "severe enough". I hope I'm wrong as a first-time Porsche owner.
1. Snapped bolts.......
That's it. The bolts being used. There's a lot of discussion about how much torque and then turn 90 degrees more..... The fact still remains Porsche is using an incorrect grade of aluminum bolt. Possibly the wrong bolt all together. What is being used is too brittle and as we're finding out, they're snapping in half. So, what are the alternatives?
Porsche could issue a TSB stating to use a different bolt. Maybe steel. Maybe a higher torque grade aluminum bolt, if a type exists. We ourselves could request the Porsche dealership to use a bolt of a higher caliber. But, if it's not OEM, they'd beg off and refuse unless you know someone there and get it done as a favor.
Aside from that, I believe this is going to keep happening even after a fix. Eventually, I see Porsche pushing back on this and refuse the work unless it's "severe enough". I hope I'm wrong as a first-time Porsche owner.