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Suggesting that the problem was due to inclusions is a stretch at best.
In reality, all castings have inclusions. They are using a new source in Germany for the fingers. These fingers are not cast but made by a process called MIM, metal injection molding. This process depending on the material you use, cavity and design, etc., can have an inclusion problem. Its not that the inclusion will break the piece, but you can have the DLC fracture over the hole, meaning the inclusion is really a small hole at the surface level and then the wear starts.
As far as a stretch, you will need to take that up with Dr Walliser.
You describe the exact failure mode he described. The inclusion close to the surface causes a crack in the DLC, that then chips and starts a wear point. So we will agree to agree.
As far as a stretch, you will need to take that up with Dr Walliser.
You describe the exact failure mode he described. The inclusion close to the surface causes a crack in the DLC, that then chips and starts a wear point. So we will agree to agree.
If you were to give an explanation as to why DLC or any other type of coating fails on a cast part, an inclusion close to the surface would be a typical cause and answer.
Its always possible that some fingers have inclusions near the surface. This should be expected on any cast part. However, this is not the cause of the Porsche finger problem.
The problem is caused by lack of oil. With no oil between the cam lobe and the finger, friction and heat is created. Oil is used to lower the friction and remove the heat. Failure to do so results in metal on metal contact. The cam lobe is "wiped" across the finger pad to open and close the valve. But when the valve is closed, an oil film is created between the finger and the camshaft base circle trapping oil. This oil then lubricates the lobe as its "wiped" across the finger. No oil, no lubrication.
This is what I have been told and shown.
The cylinder head has oiling nozzles located on the bottom rail and these squirt oil upwards towards the exhaust fingers. This oil cannot oil the Intake fingers as the exhaust valve train blocks its direction. The exhaust fingers cannot trap oil between the camshaft and fingers as the finger closes down this gap.
The fingers are hydraulically operated. Oil pressure pushes the finger hard into the camshaft eliminating any gap for oil to be used as an oil film lubricating and removing heat caused by this friction.
Early engines had no coating on the cam lobes, so the lobes wear and this creates even more friction. As the lobes wear the oil pressure continues to push the finger into the lobe. This was why the oil pressure was continually adjusted in recalls.
Coating both the lobes and fingers helps give the issue some added life, but these parts will still fail. Coating cannot make up for a lack of oil.
Porsche recognized this design fault and made the 991.2 engine "solid lash" where a lash cap is used to set a small distance between the camshaft base and the finger to always control the oil film.
You were told what can happen in a general sense but not what actually is happening inside your engine. Had they shown you a cylinder head it would have become obvious why this issue is happening.
A more in depth explanation along with photos will be posted showing the exact issue and cause.
Location: The way to hell is paved by good intentions “Wenn ich Purist höre...entsichere ich meinen Browning” "Myths are fuel for marketing (and nowadays for flippers too,,,)" time to time is not sufficient to be a saint, you must be also an Hero
It s a design fault that do not resist ppl using any kind of dirty fuel or wrong oil density or not warming/cooling the engine properly (like a 9krpms was a prius..)
combined with pag arrogance that instead admitting an issue
changing oil and filters intervals to even 5000 Km or less if track used
otherwise we dont explain why some hadn t the issue
apparently playstation era engine must be fools proof
I am a non-engineer who attended the COG meeting. What ultimately gives me confidence in Porsche's solution is test results. Dr. Walliser shared images of a valve train with the new parts that had more than 2x the normal test hours under a more rigorous test regiment. The parts looked new. This, along with the warranty extension and the promise of a new engine if the issue occurs hit the mark for me. If it fails to meet the test of time I personally believe that Porsche will make good. We have about 8 years and 120k miles to find out.
With regard to the .2 GT3, I would fully expect Porsche to improve upon the design based on their experience with the .1. There is no alarming news here.
In UAE when checking in dealer it shows in their system that the warranty for 10 years for this issue or x amount of miles comes first, so if it is in their system it should be in the system in the US
Guys this is a followup from a fellow track mate from his failure at our last DE event. He experienced a CEL code while at the track and we confirmed from a reader it was a misfire on cel on CYL 4 and 5. The car was taken to the dealer on the next business day, please read the service order below. The car was diagnosed and a new engine was installed and the owner got his car back this week. The process took a little over 6 weeks but the owner is happy. Some things to note from his experience. Porsche is standing behind it's new warranty although it took a little longer than it should have. The engine installed had a "G" designation serial number on the work order. I spoke with the service manager today and he says the new warranty is in the system. The COG will continue to monitor all known problems related to this issue.
10-01-2017, 09:15 PM
