So, what does an IMS failure sound like?

went on a 450 mile drive yesterday. Half way through (going through the town of San Luis Obispo), as I'm pulling into the gas station, I hear a horrid noise that sounds suspiciously like rod knock. Yes, a slight amount of throttle, the sound changes, so I know it's not a loose exhaust banging away. To those in the know, what could be this be? A quick call to my indy mechanic and he says it can be anything from camshaft failure to IMS, to bottom end. But I guess the silver lining is that the gas station was less than a 100 yards away from SGS Porsche shop, which apparently is the top dog in central coast when it comes to all things Porsche. I pushed the car in their driveway, and left my keys and envelope. They open tomorrow so we'll know. I'm not really all that prepared for such a huge expense on a 90K mile car. What are my options if it's the worse case scenario?

Is it a tick or a knock? Ticking isn't as expensive as a knock. I have a tick that goes away when the AC compressor goes on.

specially when the a/c wasn't even on. It's got bass to it and it's coming from the passenger side, I think. I didn't keep on running the engine. As soon as i heard it, the car was off. Odd, because I was literally pulling up to the gas station.

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I think it sounds like this: "...cha - CHIIIINNNGGGGGG!

Don't they all "tick"? like a bomb ready to go off!!!

mine ticks there is an air valve that does that, but I am guessing the OP has an issue. Just so you know and AOS going out can make one hell of a loud sound that some have compared to a whale hitting the concrete after being dropped out of an airplane... I would not run the car - relax until you get the diagnosis.... hopefully it wont be a major deal. I understand your fear though - Good luck and post the shops findings

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does this set off a blinking CEL?

I really dont know, I changed my AOS prior to it making any sounds or CEL's - I would have a sick feeling in my belly if I was in your shoes, BUT there have baan many cases where the dreaded noise of death turned out to be something simple... here's wishing you the best my friend!!!

Good luck. I hope it is something simple and inexpensive...

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Could be something less than catastrophic. What was last service done to car? If plugs might be a loose plug. Could be bad serpentine belt. Sure, could be bad rod or even main bearing. But could be a broken valve spring. Could be any number of things. Worse case is it is something internal to the engine. Main or rod bearing. Or incipient IMS failure. If internal to engine, almost certainly engine will have to come out of car and cases split. Or if noise confined to head perhaps just a camshaft cover removed. Upon limited tear down and inspection mechanic might find the problem to be a jumped chain or a bad chain guide, tensioner, or even a bad scavenge pump. Your options are to replace engine with new one sourced from dealer and installed by dealer. This expensive up front but does provide you with a new engine backed by warranty on parts and labor should new engine go boom in 2 years, 24K miles or whatever warranty period is. You could have indy install new engine but if engine bad... It is rare but has happened. Read of one instance where indy installed new engine and found new engine bad. Managed to convince dealership new engine bad but it took some time and effort and to his credit this indy took the time and put out the effort, though car's owner might have footed some of the indy's time. Or have qualified indy source engine from a Porsche focused salvage yard or business. (PartsHeaven in Hayward CA sources engines salvaged from cars and there are others: Oklahoma Foreign, some place near Mami Fl. PCA magazine or Excellence carry ads for some these places.) Risky cause you don't know what you're getting but good indy should be good at inspecting/checking out engine, go to location prepared to perform a compression test provided engine in condition to be started and run. But if engine comes from a ways away... You and your indy at mercy of the reputation of the provider of the engine and how well it stands behind its engines. Almost equally risky is to have original engine torn down and fixed. Unless shop top notch Porsche engine rebuild shop...And a good one is going to be expensive. Sincerely, Macster.

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Also, read thread below titled: "Experience w/ core charge and Porsche?" Has some new/used engine replacement info and pricing you might find interesting. Sincerely, Macster.

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thanks for the info. The last service to the car (regular maint) was done 2 weeks ago. Oil change, and other items. The coolant expansion tank was replaced 4 weeks ago. But really, the upcoming sched service in a month would have covered spark plug change, and other 30K interval items. The indy shop is pretty reputable, but they don't know yet that my car is there, although tomorrow morning, they will since I had to leave the car there. I really hope it's not the worse.

Update?

I'd be interested in hearing what the outcome was as well.

Mine knocked a little after sitting awhile and the loss of oil which was on garage floor. Here is what you wanted lets hope it does not sound this bad. Faster ver adobe flash http://www.webbspot.com/Porsche/video/blownengine.swf Slow ver http://www.webbspot.com/Porsche/video/blownengine.wmv

So, update thus far: I had the car towed back to LA from San Luis Obispo and Strasse. Many thanks to them. It looks like the failure is the valve spring. My indy shop here has taken the engine out and the valve spring broke as apparently that is also a weak point in the engine. I'm having all the valve springs replaced and while i'm there, having the head ported and polished. Hopefully, that's it. Stay tuned.

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Broken valve spring the best of the worst things that could have gone wrong or the worst of the best things that could have gone wrong. Not aware valve springs particularly weak in these engines. I've seen far more cars in for worse (mainly IMS failure) than valve springs. In fact the only one I can remember was a 986 Boxster with 65K miles (DD) though I don't know year, but a 986 model that I spotted in with a broken valve spring. Intake valve. Mech. told me driver (woman) takes good care of car, too. But she drives it every day. (I have pics of combustion chambers of the one head cause I was amazed at how "clean" the chambers were.) 'course engine had to come out to remove head. Only one valve spring being replaced though. Others I'm sure were inspected though. Anyhow, in your case, glad it was not something more serious. Sincerely, Macster.

Wait, a broken valve spring and no bent valve? That's highly unlikely. Not saying it cant happen but that would be unusual IMO.

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Not unusual. Generally the valve spring breaks but doesn't go all to pieces. There is enough spring action to keep the valve retainer tight and the valve retainer keepers in place and the valve and lifter following the cam lobe profile quite accurately, though the max. revs at which valve float (at least the one with the broken spring) will occur is lower. If one would keep driving the car and reving engine to near redline eventually -- sooner than later probably -- the valve would float and perhaps kiss the piston. Then you'd have a bent valve provided the valve head didn't break loose and fall into the cylinder. If this happens... oh my. Sincerely, Macster.

Happened to us on the way to Road America earlier this year and to an unlucky couple at Blackhawk Farms this past weekend. On our car, spring broke at the base. Would intermidently float the valve, but the keepers were loctited in place by the guy who did our heads, so they stayed in place.