Cayenne Engine Replacement
#316
Just a quick question, is this just an old crusty gasket leaking into your plugs and losing power and mileage?
The gasket refresh on intake, exhaust, and throttlebody could be a simple repair....than a full on rebuild.
If it is scored already, please feel free to ignore.
The gasket refresh on intake, exhaust, and throttlebody could be a simple repair....than a full on rebuild.
If it is scored already, please feel free to ignore.
Anyone have experience with any of the USB borescopes on amazon - for cylinder inspection?
I suppose I'll go put the leak down tester onto #6 a see what happens...
#317
The problem with leak down or compression testing an engine that is starting to show signs of the failure is that the failure starts at the lower part of the cylinder. You won't necessarily notice it in a leakdown/compression test since they are done with the piston at TDC.
If it passes and you know you are having issues, put a scope in the thing.
JR
If it passes and you know you are having issues, put a scope in the thing.
JR
#318
The problem with leak down or compression testing an engine that is starting to show signs of the failure is that the failure starts at the lower part of the cylinder. You won't necessarily notice it in a leakdown/compression test since they are done with the piston at TDC.
If it passes and you know you are having issues, put a scope in the thing.
JR
If it passes and you know you are having issues, put a scope in the thing.
JR
When the issues begin, and all that's apparent is the ticking sound, 100% of that sound is occurring at BDC/ changeover. This area of the cylinder is not visible even with the piston at BDC, as the piston covers the area up.
The only way issues at this stage can be found is with the suspect piston at BDC, with the oil pan removed and a very specialized medical grade boroscope with a super thin probe being passed into the cylinder from the opposite side.
These are the reasons why most every engine we see that has failed, has been misdiagnosed.
The borescope will only show cylinder wear in advanced stages, after the engine has started to eat oil. Why? Because as the cylinder and piston skirt are damaged, that damage emanates up the bore due to the damaged piston skirt traveling through other regions of the bore.
#320
Apparently the Porsche gods decided to test me - looks like I am owner of a 2004 S with 80K in need of a rebuild. Car ran perfectly prior (never consumed any oil between oil change intervals. Feb/March engine developed oil consumption issue 1 qt ~1K miles. based on spark plug inspection of drivers side bank, looks like Cyl #6 is primary offender. I still need to pull the heads and have a look inside but trying to come to grips with what its going to cost all in to rebuild the engine.
I need to DIY rebuild my engine - I love the satisfaction of performing the work and work for a living... I have always loved the brand.
If the root cause is temperature extremes, internal clearance issues and thermal expansion at warm up. Is the Nickasil plating as part of repair required vs. oversize pistons with bore/hone/polish with pads and paste to get to OEM cylinder wall finish?
It makes sense that key part to a proper outcome from a rebuild is - what clearance's are required to make a rebuild work. For those going the DIY route what did you do for piston selection and cylinder tolerance?
Matt
I need to DIY rebuild my engine - I love the satisfaction of performing the work and work for a living... I have always loved the brand.
If the root cause is temperature extremes, internal clearance issues and thermal expansion at warm up. Is the Nickasil plating as part of repair required vs. oversize pistons with bore/hone/polish with pads and paste to get to OEM cylinder wall finish?
It makes sense that key part to a proper outcome from a rebuild is - what clearance's are required to make a rebuild work. For those going the DIY route what did you do for piston selection and cylinder tolerance?
Matt
My 04 turbo with 240,000km uses about 1 litre every 10,000km
#321
These problems start at BDC, under the crown of the piston. The dwell time of the piston and changeover from down to up motion makes the piston rock, and load more at this position. This is also part of the cylinder that warms up slowest, as it is out of the coolant path, so it stays in a contracted state longest.
When the issues begin, and all that's apparent is the ticking sound, 100% of that sound is occurring at BDC/ changeover. This area of the cylinder is not visible even with the piston at BDC, as the piston covers the area up.
The only way issues at this stage can be found is with the suspect piston at BDC, with the oil pan removed and a very specialized medical grade boroscope with a super thin probe being passed into the cylinder from the opposite side.
These are the reasons why most every engine we see that has failed, has been misdiagnosed.
The borescope will only show cylinder wear in advanced stages, after the engine has started to eat oil. Why? Because as the cylinder and piston skirt are damaged, that damage emanates up the bore due to the damaged piston skirt traveling through other regions of the bore.
When the issues begin, and all that's apparent is the ticking sound, 100% of that sound is occurring at BDC/ changeover. This area of the cylinder is not visible even with the piston at BDC, as the piston covers the area up.
The only way issues at this stage can be found is with the suspect piston at BDC, with the oil pan removed and a very specialized medical grade boroscope with a super thin probe being passed into the cylinder from the opposite side.
These are the reasons why most every engine we see that has failed, has been misdiagnosed.
The borescope will only show cylinder wear in advanced stages, after the engine has started to eat oil. Why? Because as the cylinder and piston skirt are damaged, that damage emanates up the bore due to the damaged piston skirt traveling through other regions of the bore.
#322
I'd guess that after initial damage that the engine goes less than 5K miles before the symptoms appear. I think that most damage occurs i Jan- Feb each year, and we start etting reports in April, and May/ June is fioed wth them.
#323
To look at the offending bore from the back side, would the piston need to be a TDC? If it's at BDC wouldn't it still be hiding the cylinder wall from you? Or is it the piston itself you are inspecting at that point?
#324
I'm sure he meant put the piston at TDC and look at the cylinder wall from underneath.
#325
#326
Yeah that's what I figured which is why I was confused. I know Jake's reputation well enough to know that he could have just as easily had some trick that was beyond my less than mundane knowledge of engine repair though
#327
An update to my issue (2004 Cayenne S 90kmiles).
Dealership refused to assist. Contacted Germany directly, got a more polite refusal. Talked to the car owners association, their tech showed sympathy but no solution. My lawyer said that if I can present the fault as a security issue, I could have a case. That'd mean it would fall under a different category of laws.
Also talked to the motor specialist workshop that the dealership uses and they've changed 3-4 motors for the dealership due to this. I'm getting a list of the cars over here, they're not that many. If successful, I'll be making phone calls to each and every owner to ask if they've had issues.
Stirring the pot, seeing where it takes me.
Dealership refused to assist. Contacted Germany directly, got a more polite refusal. Talked to the car owners association, their tech showed sympathy but no solution. My lawyer said that if I can present the fault as a security issue, I could have a case. That'd mean it would fall under a different category of laws.
Also talked to the motor specialist workshop that the dealership uses and they've changed 3-4 motors for the dealership due to this. I'm getting a list of the cars over here, they're not that many. If successful, I'll be making phone calls to each and every owner to ask if they've had issues.
Stirring the pot, seeing where it takes me.
#329
#330
Well 2008+ NA v8 is 4.8l and not the original 4.5l v8 that seems to experience the most failures. The 4.8l NA doesn't fail at a statistically significant level as far as I can tell.