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Discussion Starter #1
Hello guys. Lately my 07 Cayman S has started showing a few slightly worrying symptoms. First I started noticing a slight smell of burnt oil after an aggressive drive. the smell seems to be stronger on the driver's side of the car, near the intake. Then recently I started noticing some oil loss. There is no evidence of any leaks, but I had to add oil after 2000 miles last oil change. and it is reading slightly low already after about 5 miles on the most recent change. Then this week it has started idling rough on startup, and giving a slight valve clatter for about a half second on startup, which seems to also be coming from the driver's side.

Any thoughts on what it could be other than bad A/O seperator?
 

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Those are all bad AOS signs. The only other symptom you didn't mention for a bad AOS is sooty exhaust tip. Start with replacing it, esp if it hasn't been replaced lately, and go from there before getting all worried.
 

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Has anyone heard of a bad AOS causing a camshaft plug to pop out?
I had a vacuum pump failure last summer...driven off one of the cams. And now that you mention it I did have to replace the AOS on the service prior to that incident. AOS hadn’t failed, but was leaking.

Don’t think they’re related, but something caused that vacuum pump shaft to seize...

Edit: vacuum pump failure thread here: https://www.planet-9.com/987-cayman-and-boxster-service-and-tech/232413-cayman-r-death-rattle.html
 

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Has anyone heard of a bad AOS causing a camshaft plug to pop out?
I think someone on 986forum had this happen with his 986.
 

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Discussion Starter #6
So I changed out the AOS last weekend, and holy crap I should have done that sooner. It transformed the car, and has apparently been bad since before I bought the car in 2017.

It wasn't smoking noticably from the tailpipe or anything, and for most of that time it did not seem to be burning oil in any noticeable quantity, but it did always have the oil smell coming from the area of the intake duct after a good thrashing, and a very slightly wobbly idle. Those two symptoms are now gone, though it did take a while for all of the oil to burn out of the intake and the smell was actually stronger the first few times I drove it after doing the job.

Other things that changed.

The car has always had a strange tendency to suddenly stall at creeping speeds like backing into a tight spot. There would be no warning, the car would be doing fine and then BANG, stalled. It made me feel like I forgot how to drive a manual. It was also rather tricky to get off the line, especually in sport mode. Nearly every person who has ever driven the car has stalled it at least once. I thought it must just be a reality with a lighter reciprocating mass like these engines have. Nope. It was the AOS apparently, as that symptom is completely gone now. The car can even recover from being slightly bogged now. Before it would have stalled long before it bogged down, so I never even saw it bog before.

Low end torque is vastly improved. Previously, torque at anywhere under around 3,000 RPM was pretty pathetic. I always just thought that was a reality of a high revving engine. It's much better now, which makes putering around in small villiages and the like here in Germany at 30 KPH a lot more relaxing as I can now leave it in third rather than having to drop down to second.

Overall engine smoothness and power is also improved. It always felt like a smooth engine to me, but now it is next level, and the characteristic of the sound is also more mellow, especially when cruising at high speeds on the autobahn. I find myself just cruising or slowly accelerating through a gear at high revs under low throttle when there is no room to stretch your legs, because it just sounds so damn good now. It feels like it is still improving the further I drive it too, maybe the adaptive electronics ares till catching up to the change?

Best guess is that there AOS had a slight tear that was allowing some air through and messing with fuel metering measurements. Anyone have any more concise info?
 

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That's an interesting set of observations related to the stalling feeshta.

As I had replaced quite a few wear and tear items The car did occasionally stall on very steep slopes but did so very rarely that it was difficult to diagnose. I didn't correlate the AOS to the stall issue - I thought might have been related to the starter getting stuck (they were replaced at the same time). Mine too had no oil consumption issues and smoky start ups were quite rare and the AOS was replaced purely as a preventative maintenance. Now have much more stable idle on hill slopes and hill starts.

not sure about extra smoothness or power - I think the fresh spark plugs, air filter service, intake cleaning probably contributed too. putting my favourite RON100 fuel kicks things up a notch though!
 

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Discussion Starter #8
Well, the jealous lady giveth, and she taketh away. As soon as I got her running all nice, she developed another issue. This time, a rattling noise that I couldn't quite isolate since it started yesterday. Well, at least until this evening, when the rattle revealed itself to be coming from one of the under body trays, which came loose and started dragging on the ground at like 110 mph on the autobahn. DOH!
 
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