Is it really IMS failure?? Carnage pics and detail within!
01-12-2009, 12:47 PM
#1
Burning Brakes
Thread Starter
Is it really IMS failure?? Carnage pics and detail within!
Victim: 2001 M96 engine pulled from a Boxster S. Mileage reported to be 45K
Catastrophic Failure
MOF #14
We have discovered another MOF (Mode Of Failure) related to the M96 engine. This one is our most recent tear down that occurred with a 45K mile engine. It is one of the most radical failures that could occur with an engine and we have gained a good understanding of why it occurred. More importantly we are in work already on another "overkill" part to solve this issue that we can apply during our engine updates for our complete engines and component kits.
This is interesting, because this engine fooled us, it also fooled a Porsche Dealership and another independent Porsche shop that had diagnosed the engine prior to it being sent into us. The engine had all the classic symptoms of a seriously failed IMS that had resulted in valve timing alterations, thus colliding the majority of the valves with the pistons, a true nasty affair. When the intake manifold was pulled we immediately saw carnage (broken valves and chunks of piston in the intake ports!) and since I love to dissect engine failures I stayed late to see what was inside this beast.
As the engine was torn down I was expecting to see the IMS shredded, but every time we turned the engine while removing the valve train the only symptom that the engine had was altered valve timing, this was odd. Typically when an IMS fails this badly the shaft shears in half and "parks" the valve train that operates from the opposite end of the IMS drive, located at the flywheel end of the engine (I am trying to explain this so you guys can understand!) and that results in all the things we had witnessed. When this happens the IMS will not turn, so the oil pump stops functioning and 3 cylinders worth of valves stop actuating, resulting in a big mess.
This is where it gets interesting:
When the IMS fails to the point of allowing piston collisions with the valves the IMS is most always sheared.. But when this engine was rotated fore and aft the IMS was responsive to the change in crank position and the typical damage to the oil pump that results from IMS failure was not present.
How could an engine have such a radical failure, with all the same initial symptoms as the IMS failure and have an IMS that was responsive to crank position changes, intact and still functional??? Read on...
When the first cylinder head was removed the engine still had all the symptoms of an IMS failure, but when the second head was removed that cylinder head was found to be perfectly intact with zero piston/valve interference and no damage. The engine was still spotlessly clean inside and showed no signs of abnormal wear on the "intact" bank of cylinders.
As we went deeper it got interesting as it seemed the valve timing was radically off on both sides of the engine, but all the timing chains were intact, nothing was broken and all was in decent condition. At this point of the autopsy we knew that when the case was split we'd find something we hadn't seen before.
When the case was split the IMS came out in good condition without any oil inside it and without any signs of bearing failure or wear. We immediately removed the crank carrier and then we saw the culprit..... The crank/ IMS drive chain tensioner pad was non existant and the tensioner was broken in half! We then dug through the rubble and found the broken pieces and started putting the pieces together to figure out what happened.
Why the valve timing changed:
Because the main drive chain for the IMS lost all tension when the "tensioner" sheared in half, thus allowing the IMS to stop rotating and "parking" the valves. When this occurred a couple of cylinders had open and partially open valves that then collided with their pistons and that resulted in scattered parts, a loud bang and chunks of piston being emitted from the tail pipe...
What we learned:
Something we had never really paid close attention to was the shape and thickness of this tensioner through the various years and models of the M96 engine. We pulled this piece from several engines and started comparing them in shape, interchange, composition and design. We immediately noted that the the early 2.5 tensioner was thicker across the area where this tensioner had broken and that the early unit also had a hardened steel contact surface for the chain adjuster to ride against. The later 3.2 unit had been made thinner through the area where the breakage occurred and had a PLASTIC surface for the chain adjuster to contact.
The part number from the two parts were the same, but one was a .4 while the other had a .5 suffix.
So, why was this part changed? Why would anyone ever replace a hardened steel wear surface with something comprised of plastic, when even the steel wear surface does typically wear....
This is a MOF that we have never seen before and never heard of occurring. After seeing this failure and it's symptoms I believe that some of the "IMS failures" that are diagnosed without an engine tear down are actually this MOF, or at least something similar to it, that cannot be thoroughly understood without complete dissection of the engine.
That said, we are already in work creating a two new components that will solve this MOF issue. First we are making a billet aluminum tensioner unit made to use the OE tensioner pad, this will replace the lightweight, cast aluminum factory unit. This will incorporate a larger, tool steel wear surface much like the earlier 2.5 unit pictured below. Making the wear surface larger will increase the contact patch that the chain adjuster sees, thus increasing service life.
Secondly we are making the wear surface "button" compliant with the OE tensioner, so those that have the early tensioner can replace their wear surface with a larger, stronger part if they don't choose to utilize the entire billet tensioner that we are creating.
I'll never trust one of these OE tensioners again, we'll be applying the billet units to ALL our engines effective immediately and all builds are currently halted while this component is being made.
The key to avoiding problems like these are to make the parts heavier duty than they "need" to be on paper... I call it "overkill Engineering" and it's what keeps things from failing... Its nothing more than classic hotrodding being applied to these newer, robotically assembled, mass produced engines.
We are now going through cores and doing research trying to specify when Porsche changed this tensioner.... I'll report back when we have concrete evidence.
Now for the pictures... More will be posted today on the "reliability" page at www.flat6innovations.com
The pictures speak for themselves, its mass carnage of an unreal kind.. The kind of stuff that makes it to our "trophy Shelf" filled with offerings to the Gods of Speed...
Catastrophic Failure
MOF #14
We have discovered another MOF (Mode Of Failure) related to the M96 engine. This one is our most recent tear down that occurred with a 45K mile engine. It is one of the most radical failures that could occur with an engine and we have gained a good understanding of why it occurred. More importantly we are in work already on another "overkill" part to solve this issue that we can apply during our engine updates for our complete engines and component kits.
This is interesting, because this engine fooled us, it also fooled a Porsche Dealership and another independent Porsche shop that had diagnosed the engine prior to it being sent into us. The engine had all the classic symptoms of a seriously failed IMS that had resulted in valve timing alterations, thus colliding the majority of the valves with the pistons, a true nasty affair. When the intake manifold was pulled we immediately saw carnage (broken valves and chunks of piston in the intake ports!) and since I love to dissect engine failures I stayed late to see what was inside this beast.
As the engine was torn down I was expecting to see the IMS shredded, but every time we turned the engine while removing the valve train the only symptom that the engine had was altered valve timing, this was odd. Typically when an IMS fails this badly the shaft shears in half and "parks" the valve train that operates from the opposite end of the IMS drive, located at the flywheel end of the engine (I am trying to explain this so you guys can understand!) and that results in all the things we had witnessed. When this happens the IMS will not turn, so the oil pump stops functioning and 3 cylinders worth of valves stop actuating, resulting in a big mess.
This is where it gets interesting:
When the IMS fails to the point of allowing piston collisions with the valves the IMS is most always sheared.. But when this engine was rotated fore and aft the IMS was responsive to the change in crank position and the typical damage to the oil pump that results from IMS failure was not present.
How could an engine have such a radical failure, with all the same initial symptoms as the IMS failure and have an IMS that was responsive to crank position changes, intact and still functional??? Read on...
When the first cylinder head was removed the engine still had all the symptoms of an IMS failure, but when the second head was removed that cylinder head was found to be perfectly intact with zero piston/valve interference and no damage. The engine was still spotlessly clean inside and showed no signs of abnormal wear on the "intact" bank of cylinders.
As we went deeper it got interesting as it seemed the valve timing was radically off on both sides of the engine, but all the timing chains were intact, nothing was broken and all was in decent condition. At this point of the autopsy we knew that when the case was split we'd find something we hadn't seen before.
When the case was split the IMS came out in good condition without any oil inside it and without any signs of bearing failure or wear. We immediately removed the crank carrier and then we saw the culprit..... The crank/ IMS drive chain tensioner pad was non existant and the tensioner was broken in half! We then dug through the rubble and found the broken pieces and started putting the pieces together to figure out what happened.
Why the valve timing changed:
Because the main drive chain for the IMS lost all tension when the "tensioner" sheared in half, thus allowing the IMS to stop rotating and "parking" the valves. When this occurred a couple of cylinders had open and partially open valves that then collided with their pistons and that resulted in scattered parts, a loud bang and chunks of piston being emitted from the tail pipe...
What we learned:
Something we had never really paid close attention to was the shape and thickness of this tensioner through the various years and models of the M96 engine. We pulled this piece from several engines and started comparing them in shape, interchange, composition and design. We immediately noted that the the early 2.5 tensioner was thicker across the area where this tensioner had broken and that the early unit also had a hardened steel contact surface for the chain adjuster to ride against. The later 3.2 unit had been made thinner through the area where the breakage occurred and had a PLASTIC surface for the chain adjuster to contact.
The part number from the two parts were the same, but one was a .4 while the other had a .5 suffix.
So, why was this part changed? Why would anyone ever replace a hardened steel wear surface with something comprised of plastic, when even the steel wear surface does typically wear....
This is a MOF that we have never seen before and never heard of occurring. After seeing this failure and it's symptoms I believe that some of the "IMS failures" that are diagnosed without an engine tear down are actually this MOF, or at least something similar to it, that cannot be thoroughly understood without complete dissection of the engine.
That said, we are already in work creating a two new components that will solve this MOF issue. First we are making a billet aluminum tensioner unit made to use the OE tensioner pad, this will replace the lightweight, cast aluminum factory unit. This will incorporate a larger, tool steel wear surface much like the earlier 2.5 unit pictured below. Making the wear surface larger will increase the contact patch that the chain adjuster sees, thus increasing service life.
Secondly we are making the wear surface "button" compliant with the OE tensioner, so those that have the early tensioner can replace their wear surface with a larger, stronger part if they don't choose to utilize the entire billet tensioner that we are creating.
I'll never trust one of these OE tensioners again, we'll be applying the billet units to ALL our engines effective immediately and all builds are currently halted while this component is being made.
The key to avoiding problems like these are to make the parts heavier duty than they "need" to be on paper... I call it "overkill Engineering" and it's what keeps things from failing... Its nothing more than classic hotrodding being applied to these newer, robotically assembled, mass produced engines.
We are now going through cores and doing research trying to specify when Porsche changed this tensioner.... I'll report back when we have concrete evidence.
Now for the pictures... More will be posted today on the "reliability" page at www.flat6innovations.com
The pictures speak for themselves, its mass carnage of an unreal kind.. The kind of stuff that makes it to our "trophy Shelf" filled with offerings to the Gods of Speed...
Last edited by Jake Raby; 01-11-2015 at 11:56 PM.
01-12-2009, 01:48 PM
#2
Herr Unmöglich
Rennlist Member
Rennlist Member
Thanks for the great explanation and pictures Jake. My 01S has just over 60K on it, and some of this stuff makes me wonder. I love reading about your teardowns so please keep the information coming to us!
01-12-2009, 03:06 PM
#5
Race Director
Why not valve/piston collision signs on both heads?
To me that one head suffered valve/piston contact and the other head did not suggests a failure of the cam drive from the IMS to the exhaust cam of that head, or even a failure of the chain between the exhaust cam and the intake cam.
Sincerely,
Macster.
To me that one head suffered valve/piston contact and the other head did not suggests a failure of the cam drive from the IMS to the exhaust cam of that head, or even a failure of the chain between the exhaust cam and the intake cam.
Sincerely,
Macster.
01-12-2009, 03:53 PM
#6
Burning Brakes
Thread Starter
Chains were intact, no wear on them.. I am still trying to determine exactly why at least one cylinder on the opposing bank didn't see some sort of issue..
The failure occured on the cylinder that had both intake valves open, the damage would have been limited only to that cylinder had a chunk of the piston from the adjacent cylinder not went up stream in the intake and gotten inducted into it..
There are still some unknowns at this point, but I am working on which happened first in the chain of events... It now appears that the tensioner pad may have been the first failure since it's non exiastant and had been chewed up into tiny pieces into the oil.. If the pad was extremely worn the tensioner woulod have been positioned away from the angle it was designed to operate in and thats what caused it to snap...
That means it's time to make new pads or come up with a process to eliminate wear on the OE units.
The failure occured on the cylinder that had both intake valves open, the damage would have been limited only to that cylinder had a chunk of the piston from the adjacent cylinder not went up stream in the intake and gotten inducted into it..
There are still some unknowns at this point, but I am working on which happened first in the chain of events... It now appears that the tensioner pad may have been the first failure since it's non exiastant and had been chewed up into tiny pieces into the oil.. If the pad was extremely worn the tensioner woulod have been positioned away from the angle it was designed to operate in and thats what caused it to snap...
That means it's time to make new pads or come up with a process to eliminate wear on the OE units.
01-12-2009, 04:12 PM
#7
Race Director
Never been inside Boxster engine but other engines with overhead cams...
Chains were intact, no wear on them.. I am still trying to determine exactly why at least one cylinder on the opposing bank didn't see some sort of issue..
The failure occured on the cylinder that had both intake valves open, the damage would have been limited only to that cylinder had a chunk of the piston from the adjacent cylinder not went up stream in the intake and gotten inducted into it..
There are still some unknowns at this point, but I am working on which happened first in the chain of events... It now appears that the tensioner pad may have been the first failure since it's non exiastant and had been chewed up into tiny pieces into the oil.. If the pad was extremely worn the tensioner woulod have been positioned away from the angle it was designed to operate in and thats what caused it to snap...
That means it's time to make new pads or come up with a process to eliminate wear on the OE units.
The failure occured on the cylinder that had both intake valves open, the damage would have been limited only to that cylinder had a chunk of the piston from the adjacent cylinder not went up stream in the intake and gotten inducted into it..
There are still some unknowns at this point, but I am working on which happened first in the chain of events... It now appears that the tensioner pad may have been the first failure since it's non exiastant and had been chewed up into tiny pieces into the oil.. If the pad was extremely worn the tensioner woulod have been positioned away from the angle it was designed to operate in and thats what caused it to snap...
That means it's time to make new pads or come up with a process to eliminate wear on the OE units.
The cam chain plates wore grooves where they pressed against the guide material until the chain plates worn far enough into the material the chain rollers made contact with the material in between the grooves.
At this point wear was very low, almost non-existent because the rollers of the chain were being dragged against/along the chain guide and to some extent rolling along the chain guide.
While upon teardown the groove wear looks "bad" it really makes sense in that the guide wears to conform to the shape of the chain as it travels over the chain guide material.
My point is -- and of course I'm no expert so be kind if I'm way off base here -- my point is that a hard metal surface for the chain guide doesn't seem like the right solution to me.
A softer (relatively speaking) choice of material that would wear in but not wear out and of course would withstand the rigors of the chain running against it for thousands of hours of run time and not coming apart is another task seems to be called for.
That this material be bonded to a very robust guide that can also withstand the rigors of its required thousands of hours of engine running time is critical too.
The best chain guide material is no good if it is lying in pieces at the bottom of an engine because the chain guide bracket to which the guide material was bonded structurely failed and allowed the proper guide to chain relationship to deteriorate to the point of catastrophic failure.
Sincerely,
Macster.
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01-12-2009, 04:23 PM
#8
Burning Brakes
Thread Starter
You are exactly right.. The chain wear pad is there to wear... and the units in these engines do wear quite fast.
Finding the proper material will be difficult and we were hoping we would not have to venture down this path.. I know that Silicon Nitride would solve the issue, as it has eeliminated wear for us in other applications totally, but its costly as hell and difficult to machine.
What I am exploring now are the different coatings that can be applied to these tensioner pads to reduce friction as well as what can be added to the chain to also reduce friction on the pads.
there are some metals that could also be applied as chain wear surfaces and some specialized treatments like Casiciam coating can be used to reduce friction on these... It'll be a trial and error development for sure.. It needs to be done, because even at 30K miles the pads are worn, past 70K they are on their last legs from what we have seen so far at tear down time.
And I am leaning toward this problem being aggrevated by Porsche's selection of "recommended oil".....
Finding the proper material will be difficult and we were hoping we would not have to venture down this path.. I know that Silicon Nitride would solve the issue, as it has eeliminated wear for us in other applications totally, but its costly as hell and difficult to machine.
What I am exploring now are the different coatings that can be applied to these tensioner pads to reduce friction as well as what can be added to the chain to also reduce friction on the pads.
there are some metals that could also be applied as chain wear surfaces and some specialized treatments like Casiciam coating can be used to reduce friction on these... It'll be a trial and error development for sure.. It needs to be done, because even at 30K miles the pads are worn, past 70K they are on their last legs from what we have seen so far at tear down time.
And I am leaning toward this problem being aggrevated by Porsche's selection of "recommended oil".....
01-12-2009, 10:35 PM
#10
Burning Brakes
Thread Starter
Please elaborate...
All I will say is my updated engines are not covered by warranty if Mobil 1 oil is used. I won't say more and please do not ask... :-)
01-13-2009, 12:03 AM
#11
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Can the tension pads be changed with out a complete tear down. Is there a way to verify condition? Could a roller guide be made to take the flat guides place? OK no oil analysis. What will be in the new engines?
01-13-2009, 12:08 AM
#12
Burning Brakes
Thread Starter
No, these wear pads are deep in the engine, out of sight and impossible to be inspected...
Which "new" engines are you referring to? Ours? Porsche Reman? The new 9A1 engine?
Which "new" engines are you referring to? Ours? Porsche Reman? The new 9A1 engine?
01-13-2009, 10:51 AM
#13
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C'mon Jake. Don't be coy. I have an oil change coming up. If you had to reccomend an oil to use for a 2002 Boxster S with 36K miles, what would it be???? Engine is stock.
And thanks for sharing your research in progress. I am not an engine tinkerer (I leave that to people who know what they are doing) but I still find it fascinating.
I see a new show on Speed - Jake Raby EFI (Engine Failure Investigation).
And thanks for sharing your research in progress. I am not an engine tinkerer (I leave that to people who know what they are doing) but I still find it fascinating.
I see a new show on Speed - Jake Raby EFI (Engine Failure Investigation).
