3,4 engine spun rodbearing!!
09-13-2011, 04:42 PM
#16
Race Director
I wonder if a variocam pad became worn enough that pieces of it (or any of the other plastic parts in the engine) got into the oil passageway for that bearing.
Was there always sufficient oil in the engine? Perhaps a previous owner let the oil level get too low?
With any luck rebuild the bearing carrier, case, and you'll be back on the road.
Does it look like there was any other damage? Did the engine seize/other damage or was it still running when you pulled it apart?
This is one of the reasons why I think any owner of the M96-01 should regularly change their cam pads... here were mine after 75k. AND there were certainly bits of this pad in the oil sump, perhaps elsewhere? Only a tear down might tell me...
Was there always sufficient oil in the engine? Perhaps a previous owner let the oil level get too low?
With any luck rebuild the bearing carrier, case, and you'll be back on the road.
Does it look like there was any other damage? Did the engine seize/other damage or was it still running when you pulled it apart?
This is one of the reasons why I think any owner of the M96-01 should regularly change their cam pads... here were mine after 75k. AND there were certainly bits of this pad in the oil sump, perhaps elsewhere? Only a tear down might tell me...
Unless the pad material fails mechanically, suffers a material fatigue failure perhaps, the pads should last forever. My Boxster's passenger side VarioCam actuator was replaced (the actuator failed) but the chain rails which are in constant contact with the chain between the exhaust and intake cams showed very little wear, after nearly 240K miles.
If the chain guide/rail sheds any material -- and it can at first -- this material will end up in the oil sump. The material may first go through one oil scavage pump.
Once in the sump if they can remain on the floor of the oil sump until well forever. If they are small enough though they can get picked up by the oil flowing into the oil pump pickup and then routed to the high pressure ouil pump, the gears of this will pulverize the material.
After leaving the high pressure oil pump these pieces then will be trapped by the oil filter. They may remain in the filter medium or when the engine is shut off the back flow of oil may flush some of the pieces out of the filter back into the filter housing oil. The pieces/material do not circulate through the engine though. Once in the housing they remain there until the housing is removed and the oil with the material in it is dumped out and the old oil filter replaced with a new one.
Sincerely,
Macster.
09-13-2011, 05:21 PM
#17
Three Wheelin'
I certainly hear and understand your comments Macster.
Just thinking outside the box for a little.
Perhaps some of it is smoke, who knows for sure... but it is interesting that businesses with solid reputations would make such claims if this pad wear wasn't a problem with the early M96 engine design? And not to mention Porsche eliminating the design from the 3.6L all-together.
If not with bits of the pad clogging passageways if they are to live in the sump forever or sucked into the oil pump, then perhaps the pads snapping in two or larger pieces breaking off causing the cam chain to skip or just wear through enough to cause enough cam deviation and timing problem? (of course perhaps these problems could have been caused by improper lubrication in the first place...)
In the above pic, what of the bits below the roller that had disintegrated and fell off? Based on your comments, wouldn't the chain rollers prevent any of that type of wear? There are clearly chunks of the pad that have separated from the pad...
Last time my oil pan was off, there were many little bits of this variocam pad material in the bottom of the sump, certainly I could have kept them there and probably even added more souvenirs for someone else to find at a future date without any detriment to the engine. What was a little disturbing though was that there were also many many pieces stuck in and probably went through the oil pickup tube screen. Even if they were pulverized or flattened into ever increasingly smaller bits of material, I wonder if enough of these flattened pieces could become stuck somehow in a small oil opening before they ever made their way back into the sump or perhaps oil pump? Some of the oil passageways such as the ones on lifters are very very small. As small as the tip of a ball point pin. I don't believe it would take much silicone material or flattened cam pad material to plug a hole. Then again, with the oil pressure and intense oil flow it is also probably very unlikely to happen, but don't you think the possibility is there?
"The LN Engineering Spin-On Oil filter adapter also helps improve the longevity of your engine by providing full flow filtration, which means 100% of the oil gets filtered without having oil bypass the filter (as the factory filter housing allows for)." - Charles Navarro
Without 100% filtration, do you think some of the oil (and bits) bypass the filter and make it's way on to block an oil passageway?
"- Replace vario-cam wear pads and the 4th and 5th timing chains at 40K miles if your car is an 01 or earlier 996 or an 02 or earlier Boxster. " http://www.flat6innovations.com/pre-failure-directives
If it were made to last forever, why would someone recommend replacing it every 40,000 miles?
"Variocam tensioner from a 2.7 with D-chunk failure. Approx. 70,000 miles. All other tensioner guides in this engine were just as delaminated and worn. To solve this issue we are visiting other materials to "shoe" the guides with that can allow for wear resistant coatings to be applied." http://www.flat6innovations.com/engi...es-illustrated
If it's design was already "good enough", why would someone look into use other wear resistant coatings or materials to shoe the guides?
Again, perhaps I am thinking too far outside the box here.
Just thinking outside the box for a little.
Perhaps some of it is smoke, who knows for sure... but it is interesting that businesses with solid reputations would make such claims if this pad wear wasn't a problem with the early M96 engine design? And not to mention Porsche eliminating the design from the 3.6L all-together.
If not with bits of the pad clogging passageways if they are to live in the sump forever or sucked into the oil pump, then perhaps the pads snapping in two or larger pieces breaking off causing the cam chain to skip or just wear through enough to cause enough cam deviation and timing problem? (of course perhaps these problems could have been caused by improper lubrication in the first place...)
In the above pic, what of the bits below the roller that had disintegrated and fell off? Based on your comments, wouldn't the chain rollers prevent any of that type of wear? There are clearly chunks of the pad that have separated from the pad...
Last time my oil pan was off, there were many little bits of this variocam pad material in the bottom of the sump, certainly I could have kept them there and probably even added more souvenirs for someone else to find at a future date without any detriment to the engine. What was a little disturbing though was that there were also many many pieces stuck in and probably went through the oil pickup tube screen. Even if they were pulverized or flattened into ever increasingly smaller bits of material, I wonder if enough of these flattened pieces could become stuck somehow in a small oil opening before they ever made their way back into the sump or perhaps oil pump? Some of the oil passageways such as the ones on lifters are very very small. As small as the tip of a ball point pin. I don't believe it would take much silicone material or flattened cam pad material to plug a hole. Then again, with the oil pressure and intense oil flow it is also probably very unlikely to happen, but don't you think the possibility is there?
"The LN Engineering Spin-On Oil filter adapter also helps improve the longevity of your engine by providing full flow filtration, which means 100% of the oil gets filtered without having oil bypass the filter (as the factory filter housing allows for)." - Charles Navarro
Without 100% filtration, do you think some of the oil (and bits) bypass the filter and make it's way on to block an oil passageway?
"- Replace vario-cam wear pads and the 4th and 5th timing chains at 40K miles if your car is an 01 or earlier 996 or an 02 or earlier Boxster. " http://www.flat6innovations.com/pre-failure-directives
If it were made to last forever, why would someone recommend replacing it every 40,000 miles?
"Variocam tensioner from a 2.7 with D-chunk failure. Approx. 70,000 miles. All other tensioner guides in this engine were just as delaminated and worn. To solve this issue we are visiting other materials to "shoe" the guides with that can allow for wear resistant coatings to be applied." http://www.flat6innovations.com/engi...es-illustrated
If it's design was already "good enough", why would someone look into use other wear resistant coatings or materials to shoe the guides?
Again, perhaps I am thinking too far outside the box here.
09-13-2011, 11:49 PM
#18
Rennlist Member
While that pad wear looks bad it is not bad at all. The new pads wear in very quickly from the abrasion of the chain side rails until the chain rollers begin to make contact with the pad. Then the wear becomes nil. Essentially the chain rollers roll over the pad.
.
Sincerely,
Macster.
.
Sincerely,
Macster.
09-14-2011, 12:19 AM
#19
Three Wheelin'
The rectangular area in red is the area the chain rollers come into contact with.
Can you see any pitting or wear in this area? Does that wear look anything like the wear that is presumably caused by the chain link edges on the same surface?
Can you see any pitting or wear in this area? Does that wear look anything like the wear that is presumably caused by the chain link edges on the same surface?
09-14-2011, 12:49 AM
#21
Race Director
Well, I do not know what businesses claim needs to be done. I honestly don't pay that much attention.
The engine will tell you what needs to be done, if anything.
The chain guide rails (and this includes their composite plastic coverings) are pretty tough items and designed to avoid wear. I have to add though if a chain tensioner goes bad or starts to go bad this can lead to accelerated wear and tear on the chain guide rails because the chain instead of having constant pressure applied to it instead gets varying pressure and this can result in the chain slapping the chain rails/guides and the rails/guides do not like this.
But barring some outright mechanical failure or weakness in a tensioner...The chain constantly runs across this material the whole time the engine is running. If the material were not up to the task, if the design were not up to the task, the things would not last 40K miles. They'd be lucky to last 400 miles.
And I can't believe there is that much variation that one car would end up with chain guide/pad material that would last in some cases hundreds of thousands of miles while another otherwise identical car treated in the same fashion would end up with chain guide/pad material that required replacing after just 40K miles.
The cost to replace these rails is not insignificant. In the case of my Boxster to get at the actuator guides/rails the labor is 9 hours and the actuator (with new rails) is almost $900. (The rails might be available separately though.) While one is there then if the rails require replacing the solenoid does too and that's another almost $800.
My local Porsche dealer charges $150/hour labor so 9 times $150 is $1350. Add in say $1700 worth of actuator/solenoid and that brings the job cost up to $3000 and change. Then in the case of my Boxster new camshaft cover bolts are needed -- the bolts are not supposed to be reused -- and some other hardware, then tax and well, one is looking at $3200 or so. And that's just one bank.
Sure an indy might be able to do the work for less money but still that's a large amount of money to spend with no signs of it being necessary.
Then there are the chain guides/rails for each of the IMS to exhaust cam chain runs and to get at one I think the transmission has to come of the car.
Then there is the crankshaft to IMS chain drive and its rails.
Do not forget the tensioners all around.
Do all of the above and one is looking at a huge expense. Every 40K miles?
I have to point out too that with all of these new parts in the engine the risk of one of the new parts experiencing premature failure is high so there's that increased risk.
My 02 Boxster has 245K miles on it. (You just knew I was going to drag this car into the discussion...). Divide that mileage by 40K and that's 6 times I would have had to have the car in for this chain guide/rail servicing.
Six Times!
Roughly I would have spent $36K on this preventative maintenance since 02.
I note I only paid $42K and change for the car new in 02.
No way.
If any of my Porsches needed this level of preventative maintenance every 40K miles I'd scrap the cars and use the money buy a better designed car.
So, I chose not to have it done. But I also am prepared to live with the consequences if I make the wrong decision.
But you have to do what you feel is best for you and your car. If this means replacing the chain rails and so on every 40K miles, then that decision is between you and the person you are getting this advice from.
Sincerely,
Macster.
The engine will tell you what needs to be done, if anything.
The chain guide rails (and this includes their composite plastic coverings) are pretty tough items and designed to avoid wear. I have to add though if a chain tensioner goes bad or starts to go bad this can lead to accelerated wear and tear on the chain guide rails because the chain instead of having constant pressure applied to it instead gets varying pressure and this can result in the chain slapping the chain rails/guides and the rails/guides do not like this.
But barring some outright mechanical failure or weakness in a tensioner...The chain constantly runs across this material the whole time the engine is running. If the material were not up to the task, if the design were not up to the task, the things would not last 40K miles. They'd be lucky to last 400 miles.
And I can't believe there is that much variation that one car would end up with chain guide/pad material that would last in some cases hundreds of thousands of miles while another otherwise identical car treated in the same fashion would end up with chain guide/pad material that required replacing after just 40K miles.
The cost to replace these rails is not insignificant. In the case of my Boxster to get at the actuator guides/rails the labor is 9 hours and the actuator (with new rails) is almost $900. (The rails might be available separately though.) While one is there then if the rails require replacing the solenoid does too and that's another almost $800.
My local Porsche dealer charges $150/hour labor so 9 times $150 is $1350. Add in say $1700 worth of actuator/solenoid and that brings the job cost up to $3000 and change. Then in the case of my Boxster new camshaft cover bolts are needed -- the bolts are not supposed to be reused -- and some other hardware, then tax and well, one is looking at $3200 or so. And that's just one bank.
Sure an indy might be able to do the work for less money but still that's a large amount of money to spend with no signs of it being necessary.
Then there are the chain guides/rails for each of the IMS to exhaust cam chain runs and to get at one I think the transmission has to come of the car.
Then there is the crankshaft to IMS chain drive and its rails.
Do not forget the tensioners all around.
Do all of the above and one is looking at a huge expense. Every 40K miles?
I have to point out too that with all of these new parts in the engine the risk of one of the new parts experiencing premature failure is high so there's that increased risk.
My 02 Boxster has 245K miles on it. (You just knew I was going to drag this car into the discussion...). Divide that mileage by 40K and that's 6 times I would have had to have the car in for this chain guide/rail servicing.
Six Times!
Roughly I would have spent $36K on this preventative maintenance since 02.
I note I only paid $42K and change for the car new in 02.
No way.
If any of my Porsches needed this level of preventative maintenance every 40K miles I'd scrap the cars and use the money buy a better designed car.
So, I chose not to have it done. But I also am prepared to live with the consequences if I make the wrong decision.
But you have to do what you feel is best for you and your car. If this means replacing the chain rails and so on every 40K miles, then that decision is between you and the person you are getting this advice from.
Sincerely,
Macster.
09-14-2011, 01:04 AM
#22
Race Director
I certainly hear and understand your comments Macster.
Just thinking outside the box for a little.
Perhaps some of it is smoke, who knows for sure... but it is interesting that businesses with solid reputations would make such claims if this pad wear wasn't a problem with the early M96 engine design? And not to mention Porsche eliminating the design from the 3.6L all-together.
If not with bits of the pad clogging passageways if they are to live in the sump forever or sucked into the oil pump, then perhaps the pads snapping in two or larger pieces breaking off causing the cam chain to skip or just wear through enough to cause enough cam deviation and timing problem? (of course perhaps these problems could have been caused by improper lubrication in the first place...)
In the above pic, what of the bits below the roller that had disintegrated and fell off? Based on your comments, wouldn't the chain rollers prevent any of that type of wear? There are clearly chunks of the pad that have separated from the pad...
Last time my oil pan was off, there were many little bits of this variocam pad material in the bottom of the sump, certainly I could have kept them there and probably even added more souvenirs for someone else to find at a future date without any detriment to the engine. What was a little disturbing though was that there were also many many pieces stuck in and probably went through the oil pickup tube screen. Even if they were pulverized or flattened into ever increasingly smaller bits of material, I wonder if enough of these flattened pieces could become stuck somehow in a small oil opening before they ever made their way back into the sump or perhaps oil pump? Some of the oil passageways such as the ones on lifters are very very small. As small as the tip of a ball point pin. I don't believe it would take much silicone material or flattened cam pad material to plug a hole. Then again, with the oil pressure and intense oil flow it is also probably very unlikely to happen, but don't you think the possibility is there?
"The LN Engineering Spin-On Oil filter adapter also helps improve the longevity of your engine by providing full flow filtration, which means 100% of the oil gets filtered without having oil bypass the filter (as the factory filter housing allows for)." - Charles Navarro
Without 100% filtration, do you think some of the oil (and bits) bypass the filter and make it's way on to block an oil passageway?
"- Replace vario-cam wear pads and the 4th and 5th timing chains at 40K miles if your car is an 01 or earlier 996 or an 02 or earlier Boxster. " http://www.flat6innovations.com/pre-failure-directives
If it were made to last forever, why would someone recommend replacing it every 40,000 miles?
"Variocam tensioner from a 2.7 with D-chunk failure. Approx. 70,000 miles. All other tensioner guides in this engine were just as delaminated and worn. To solve this issue we are visiting other materials to "shoe" the guides with that can allow for wear resistant coatings to be applied." http://www.flat6innovations.com/engi...es-illustrated
If it's design was already "good enough", why would someone look into use other wear resistant coatings or materials to shoe the guides?
Again, perhaps I am thinking too far outside the box here.
Just thinking outside the box for a little.
Perhaps some of it is smoke, who knows for sure... but it is interesting that businesses with solid reputations would make such claims if this pad wear wasn't a problem with the early M96 engine design? And not to mention Porsche eliminating the design from the 3.6L all-together.
If not with bits of the pad clogging passageways if they are to live in the sump forever or sucked into the oil pump, then perhaps the pads snapping in two or larger pieces breaking off causing the cam chain to skip or just wear through enough to cause enough cam deviation and timing problem? (of course perhaps these problems could have been caused by improper lubrication in the first place...)
In the above pic, what of the bits below the roller that had disintegrated and fell off? Based on your comments, wouldn't the chain rollers prevent any of that type of wear? There are clearly chunks of the pad that have separated from the pad...
Last time my oil pan was off, there were many little bits of this variocam pad material in the bottom of the sump, certainly I could have kept them there and probably even added more souvenirs for someone else to find at a future date without any detriment to the engine. What was a little disturbing though was that there were also many many pieces stuck in and probably went through the oil pickup tube screen. Even if they were pulverized or flattened into ever increasingly smaller bits of material, I wonder if enough of these flattened pieces could become stuck somehow in a small oil opening before they ever made their way back into the sump or perhaps oil pump? Some of the oil passageways such as the ones on lifters are very very small. As small as the tip of a ball point pin. I don't believe it would take much silicone material or flattened cam pad material to plug a hole. Then again, with the oil pressure and intense oil flow it is also probably very unlikely to happen, but don't you think the possibility is there?
"The LN Engineering Spin-On Oil filter adapter also helps improve the longevity of your engine by providing full flow filtration, which means 100% of the oil gets filtered without having oil bypass the filter (as the factory filter housing allows for)." - Charles Navarro
Without 100% filtration, do you think some of the oil (and bits) bypass the filter and make it's way on to block an oil passageway?
"- Replace vario-cam wear pads and the 4th and 5th timing chains at 40K miles if your car is an 01 or earlier 996 or an 02 or earlier Boxster. " http://www.flat6innovations.com/pre-failure-directives
If it were made to last forever, why would someone recommend replacing it every 40,000 miles?
"Variocam tensioner from a 2.7 with D-chunk failure. Approx. 70,000 miles. All other tensioner guides in this engine were just as delaminated and worn. To solve this issue we are visiting other materials to "shoe" the guides with that can allow for wear resistant coatings to be applied." http://www.flat6innovations.com/engi...es-illustrated
If it's design was already "good enough", why would someone look into use other wear resistant coatings or materials to shoe the guides?
Again, perhaps I am thinking too far outside the box here.
I believe the filtration is adequate. My experience with my cars tends to reinforce my belief. But obviously there are those that believe differently and have different experiences which reinforce their beliefs.
I am prepared to live with the consequences of my beliefs. If the engine expires tomorrow due to inadequate filtering of the oil, or using an out of favor oil, or for any number of reasons, well, the next time I might do things differently.
Actually, there'd not be a next time because I'd not own another Porsche. I've never had any car I've owned have its engine fail for any reason or even wear out (though I bought a pickup truck with a 'sick' engine that I had to rebuild when I found the ticking was the camshaft bearings missing and the oil pressure nearly non-existent) and I'm not about to put up with that behavior from a Porsche.
Sincerely,
Macster.
09-14-2011, 01:19 AM
#23
Rennlist Member
My cam chain wear pads ar 88,K miles
09-14-2011, 01:50 AM
#24
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I think that most of us have seen that varicampad's was made on wrong materials. New pad that I changed, were made of completely difrent plastic. I drove with those about 10k miles, and those are still like new. No wear what so ever.
My car has 60k miles, so at 50k I changed the pad's that looked just like the prodriver and lograys.
For the oilfiltration.What was inside my motor, supports macster's theory. There was lots of metaldebries in the oilfilter, but none in the highpressure side after the filter. Allso allthe oilpassages in cyl.head's were comletely clean.
Jake, have you seen before that the oiljets would fail, and leave one mainbearing and conrodbearing with insufficent lubrication?
My car has 60k miles, so at 50k I changed the pad's that looked just like the prodriver and lograys.
For the oilfiltration.What was inside my motor, supports macster's theory. There was lots of metaldebries in the oilfilter, but none in the highpressure side after the filter. Allso allthe oilpassages in cyl.head's were comletely clean.
Jake, have you seen before that the oiljets would fail, and leave one mainbearing and conrodbearing with insufficent lubrication?
09-14-2011, 11:26 AM
#26
Car now has 115k+, just finished a 2k trip. Avg 28mpg, car runs great. Secret is to drive theses things alot. No garage queens.
Here is a recap replacing the pads and other maintenance items.
https://rennlist.com/forums/996-foru...ed-engine.html
09-14-2011, 12:15 PM
#27
Three Wheelin'
There is at least one documented case of IMS to exhaust cam chain ramp failure, prompting one company to make a billet aluminum replacement. Although this has been the only failure I have read about.
http://www.lnengineering.com/chaintensioner.html
http://www.lnengineering.com/failedt...ade/index.html
I'm not disagreeing with you that there are engines out there with 100'ks of miles with the original pads that are probably just fine. In fact, I can't recall seeing many (if any) threads about variocam ramp failure. Are you saying that the older "plastic" that is pitted and worn will have less tendency to fail than new "plastic" which would not be scored or worn?
09-14-2011, 12:21 PM
#28
Three Wheelin'
09-14-2011, 01:16 PM
#30
Rennlist Member
The "oiljets" that press into the crankshaft carrier housing spray oil on the underside of the pistons for cooling only & only spray when oil pressure is high enough to get past the check *****. They are not designed to lubricate anything.