Certainly not one who'll offer any goodwill if indeed is reading this thread.

 

Honestly, if you are hoping for goodwill from Porsche based off a few experiences on rennlist, you are in for a sad awakening. "Oh heck, some guys on rennlist don't think our motors should be coming apart at 90k miles, lets throw them a new motor." I've been in the business too long to know they don't consider this an issue. Porsche doesn't make mistakes. The new RS's are now shattering IMS's and they don't think it is an issue. They are fully aware of this issue with the cams and tappets at Porsche Logistics, and they don't think it is an issue. Car is out of warranty....NOT their issue.

On another note, I think I have sourced a good low mileage engine for cheap, so we will probably not even attempt this one. Parts and cheap labor were already over 10k without doing anything else besies a clutch going back in.

 

"the mapping is based off load vs RPM". Can you be more specfic?

Sincerely,

Macster.

 

Macster if you happen to have the book "Porsche 996 the essential companion" the vario cam system is well explain.... Page 169-170-171


Or this explanation from 911hq.com


So what is VarioCam Plus?
Basically VarioCam Plus is a system that uses variable valve timing in conjunction with two stage valve lift on the intake side. As mentioned above the benefits to using this technology is a smother running engine, greater power and torque and better fuel consumption along with lower exhausts emissions.
You could say that this technology makes two engines out of one, in that the system facilitates optimum performance in both normal driving and high speed driving. Despite the chasm between the two driving state, VarioCam Plus achieves this by using the latest in electronic engine management system, which switches perfectly between the two state of driving. The result is greater acceleration and much smother running.

An electro hydraulically switchable tappet is a part of the two stage lift mechanism on each inlet valve. Each of the 12 tappets is made up of two concentric parts; the outer ring and a central shaft, if required, they can be locked together by way of a pin, and this is all done at the command of the engine management system. The result is that the system is now able to vary the valve lift by utilizing two large cams on the outer ring or a smaller cam lobe on the central shaft. This brought about by an electro hydraulic rotary vane adjuster at the head of the respective camshafts which facilitates the seamless timing of each valve.
Another benefit of VarioCam Plus is that it improves the engine's responsiveness during warm up in cold weather; this is accomplishes by selecting the higher lift setting and delaying the valve timing.
When the engine has low loads and medium revs, the lowered valve lift setting is activated which in turns helps to reduce fuel consumption and emissions. The engine's economy is especially improved at lower engine speeds. Conversely, maximum power and torque are achieved when the higher lift setting is selected thus allowing the timing of the valves to advance.
Consequently the engine delivers abundant torque and excellent fuel economy, relative to sports cars with similar sized engines and power output.

 

Here are a couple pictures of the cam:

Passenger side. The missing center ring correlates to the groove seen in my early front cam housing picture.


And the driver side intake cam. Notice it still has all 3 rings.


And a little better picture of one of the cam housing brackets. Pretty major crack starting.

 

Do not yet have the Porsche 996 Essential Companion book. I'll order it today.

I do know what VarioCam and VarioCam Plus are, what they do, in a general way.

I have some details on the lower level workings of the VarioCam system in my 02 Boxster. And believe it or not, I have a Turbo intake valve zero-lash lifter at my desk which of course not only provides for zero-lash valve clearance but has the mechanism which is used (under hydraulic control ultimately controlled by the engine controller) to select between the inner or outer lifter portion which changes which of the two different cam lobe profiles -- one a high lift and the other a low lift and with probably different timings as well -- the lifter and ultimately the valve follow.

But what I don't know -- and I hope the 996 Essential... book has this info -- is exactly when exactly under what conditions does the Turbo engine controller decide to advance/retard the intake valve timing and for VarioCam Plus when it does it advance/retard the intake valve timing and when does it switch from reduced lift to high lift or vice versa?

Sincerely,

Macster.

 

Macster you have various maps running at once. Throttle request, is a input. Temperature allows the load maps to be enabled. Like when you want "boost" you are actually the ECU to produce more load.

 

Guess what I did after reading these 3 pages

 

So why does this kind of failure happen? could it be human error at assembly? (at Stutgart) maybe they missed that ring on the camshaft? besides changing the oil with 5-40 every other day what else can one do to avoid these failures??

 

Doc,
I have it up on stands and I am getting ready to drop the engine. Before I was kinda scared to disassemble my motor. now i'm terrified. Maybe if the Porsche reps see an engine break at 24,000 miles they will take one off the assembly line and send it to Oregon, lol. Please keep us updated on your progress, I know it is going to help me out.
How did the Variocam look? I had the same metal particles on the actuator valve, and was thinking they came from the actuator, on the cam.
Joel

 

Kevin,

Why do you think we are seeing these issues on the tt motors (996, 997), but not on the GT3 cars?

I realize there are a lot less GT3s on the road, and the GT3 has the one piece IMS, but I don't understand why the GT3 motor seems to have less issues...

 

The cam actuators on the passenger is shot. Quite a bit of play in it. The driver's side didn't seem as bad. When rotating the crank (everything assembled), the intake cam on the passenger side would lag for a second, then snap foward.

 

The ring was definitely there when the motor was assembled as evidence in the groove in the forward cam housing. From the guys I have talked with, this ring issue is starting to become quite common.

 

spent the whole weekend getting the car ready to pull (drop) the engine. I've got just about everything disconnected and drained. any new information on your project. Have you decided to repair the cam actuator or buy a new engine. You said you have end play in the crank, how much is ok and how much is to much?
Joel

 

We are at a standstill at the moment. The cost to put this motor back together with new actuators/cam housings/cam/tappets has hit a point where I don't think it is money well spent considering the miles on the motor. We could go in and rebuild the entire engine, but what else will we find deeper? I have sourced used engines as well as given the option of a factory motor, but I think it is a little over whelming for the owner (quite understandably). Right now I just finished up boxing the parts up and the owner is going to pick them up to get them out from underneath me while he decides what he wants to do. He bought the car new for 112k in late 2001 IIRC, and is a little disappointed at 90k miles to be staring at a $20k bill. We told him to go home, and make a list of what the car means to him, all the pros/cons to help him make a decision. Right now, I think there may be more important things in his life which is understandable. I'll keep you updated as I know more.