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Weird 987.2 knock sound...

10K views 32 replies 11 participants last post by  FlyinAg  
#1 · (Edited)
Hey Porsche gurus,

I have a 2011 Cayman S PDK that I bought this summer. Had a good PPI, and no issues since I have owned it. It has just over 60k miles, and I have only put 2k miles or so on it. I drive it regularly, a few times a week. Oil was changed this summer when bought. Doesn't smoke on start normally. ONE time it smoked when started after I parked on a freakishly steep parking lot which put the right bank low, so I chalked that up to oil seeping past the rings. It smoked for a minute and that was that. I routinely check the oil and haven't noticed much if any oil consumption. Was running strong and sounding great all week. I just put a Carnewal GT exhaust on and was really enjoying it!

Today, after driving it on a few errands (car totally warmed up), I put the car in reverse to back into the driveway (thankfully I wasn't in the middle of the drive up the mountain I was thinking of taking). When the car shifted into reverse, something immediately began to knock. Not a tick, but a loud rhythmic knock. You know, the a knocking sound that would make you think stuck lifter or the dreaded rod knock. The knock seems tied to engine rpm, not gear or wheel speed. It does it at idle and when backing up in gear. It seemed like it was coming from the drivers side, but I didn't spend too much time checking for fear or further damage. I backed in the garage and shut it down, but not before grabbing a short video clip. It sounds metallic, and clunky, not like a tick. It also seems like it might knock

Collapsed lifter? Timing chain? Rod bearing? I know it is hard to tell on the internet, but was hoping someone could point it out if it was very specific sounding to them. I suppose it could also be an accessory... I have half a mind to take the belt off and fire it up...

Thoughts?

 
#2 ·
It's rpm depended, solid and clearly to me internal engine, Heavy sound makes me think rods or pistons, not valvetrain. Check for codes, use a steno scope to locate more specific area and I would get to bore scope done. Anything further than that would need disassemble.
 
#3 ·
Although I agree with Augie that it sounds a bit heavy for a lifter, internet diagnosis of sounds can be misleading. The knock appears to be occurring at half idle speed (per my quick count with a stopwatch) which would indicate a valve train issue, so I'm thinking stuck lifter, which is something that could suddenly occur with no warning.
 
#4 ·
you could try something like lucus additive to see if that cleans it out
worth $5 and some time
 
#7 · (Edited)
Started it this morning cold. Still there but very different. Less klunk and more tick, almost like an exhaust leak but still a bit metallic. I did just do the Carnewal GT last week, so maybe the gasket failed although I used a little copper gasket maker. I've had header and exhaust leaks on my old 72 Buick GS, and this is more dramatic sounding, but had that characteristic noise on the cold engine, and it sounds like it is coming from that spot. Perhaps there is a nasty harmonic from the gasket pulsing that makes the hot exhaust pipe klunk...

Will take the engine covers off and inspect, then jack the car up and check with is up on jack stands...


Update: I got to thinking, is there something that could have come loose in the exhaust that is banging around? Anyone else seen this with Carnewal? Knocking on the exhaust produces a metallic sound roughly the same pitch as the knock on the 'engine' and the engine knock does a little bit of ring to it. Could the exhaust leak excite a resonant frequency? I attached a video of my knocking and tapping the exhaust. Something is rattling either in or attached to the exhaust... more food for thought.

 
#8 ·
Not to worry, I have had that exact same sound from my motor at least 3 times over the last 5 years.
Its a collapsed lifter! Once the lifter builds back up some pressure which can take approx up to 5 -10 minutes running
the noise will slowly go away. All the Porsche motors can do this at some point in there life. Mine is an 06 3.2.
Regardless of miles.Ive seen a brand new 911 do this rite at the dealer rite in the parking lot, freaked the customer out completely.
How to keep it from ever happening again. I figured it out 3 years ago and has never happened again.
When u start your car make sure to let it warm up either by idling it or even better driving it for a few minutes before shutting it down (if u need to shut it down) to let all the lifters pressure up with oil. If u start the car cold for example in garage and back out to the driveway and immediately turn engine off say to wash it ect then go to start it 20 minutes later were its still not up to temp one or more lifters
could be not pressured up and it will stick shut and knock loudly exactly like yours does. If motor is stone cold and u start and keep driving it or its already hot this will never happen. I run 5/40 oil and change every 8000 kilometres but I dont think the oil viscosity has any bearing on this issue. If u think back to when this happened carefully, u will probably find that the car was cold ,hadn't run long or for a few minutes before turning off and then turning back on shortly after even an hr or 2 after. I doubt this is good for the cams but up until now I haven't had any other issues
that may have been created by the lifter. The holes in the lifters are extremely small and can can clog easily,i think that
the oil pressure, heat ect from the oil eventually builds the pressure back up and your good to go.Some people have new lifters installed but I think this is a flat six trait though undesirable never the less. Freaked me out first time it happened, thought a Rod bearing had gone or something else catastrophic! U should have just let the car idle until the
lifter built up pressure but if u leave the car till its stone cold and try starting it u may be ok. I just drove my car around the block a few time, no high revs to get it to warm up and help build oil pressure and eventually the noise stopped completely. But if u do as I mention u will never have anymore issues.
 
#9 ·
If u think back to when this happened carefully, u will probably find that the car was cold ,hadn't run long or for a few minutes before turning off and then turning back on shortly after even an hr or 2 after.
Yeah, only problem was that I had been driving the car all day, and was returning from an errand with a hot car. It wasn't like I had just started it, I was returning home after driving. :(
 
#14 ·
I have a 2007 Cayman S. I had a strange pronounced metallic ticking sound when I backed into a parking spot and could hear it echoing off the wall. Opened my door and heard it clearer. Thought it was an exhaust leak of some kind so I took it to my mechanic, who is a Porsche specialist--this is all he does. After going over all the alternatives, he discovered it was the flywheel which had to be replaced. Noise from flywheel was echoing through the transmission into the piping. Never would have suspected this but I would encourage you to have it checked. Good luck & hope it is something easy to fix!(y)
 
#15 ·
Lots of interesting stories here about various noises, but most seem to miss that the car got a new exhaust system and the noise did not happen until the car was put in reverse. Rod knock, turned bearings, valve train issues and other engine sounds are not going to be any different whether the car is going forward or backward. They will, however, change with rpm or engine load. And, except for stuck lifters, most sounds caused by failing internal engine parts don't go away.

On the other hand, a loose exhaust manifold can make a loud ticking sound and an exhaust pipe rubbing against something can make a knock. The volume and tone of the sound could easily be affected by engine heat, engine rpm or a change in the car's direction, because those things could affect the position of the exhaust system. If it were my car, the first thing I'd do is get it onto a lift and make sure the exhaust system was mounted properly and not hitting anywhere.
 
#16 · (Edited)
Sorry I have not reported back, this came in the middle of: a new roof, mold remediation, kid with flu, and wife within a week of our 3rds due date! Need to get it on jacks. Gary, I am hoping you are right about the manifold or exhaust!

You bring up a good point. I was surprised the first time I saw how much the exhaust system moves in this car when you accelerate. I was watching some exhaust video one night and it's pretty drastic.

Fingers crossed. It definitely seems like it comes from the drivers side.
 
#18 ·
To test the flywheel you would have to remove it and see how much play it has since these cars have a dual mass flywheel. If yours has failed it will cause a nasty vibration through the drivetrain.
 
#19 ·
Hey I lost my nuts! What the heck? The bands had also loosened up.
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Also found oil weeping here at the front drivers side.

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I know this car had a faulty AOS that was addressed post PPI and the PPI said it needed a new oil level sensor seal so maybe the weeping is left over from that. It has Total 5w40 in it.

I started it up on jacks. Noise is definitely on the front drivers side. At first thought it was maybe an exhaust manifold leak, but it's hard to tell. More I listened, the more it seemed like it could even be coming from that area where the oil was weeping. That looks like valve cover? Stuck lifter or timing chain? Need to get it higher on the jacks tomorrow and still want to take front cover off. I suppose for completeness I could do the old rod knock check by checking for piston movement on the down strick with a tool in the spark plug hole. We

It just seemed weird that it started making the noise exactly when I put it in reverse. It was perfect until that! Wouldn't a rod knock come on slowly? Would a lifter just collapse in hot motor running strong all day with no codes? I was really hoping the exhaust hardware had caused a simple exhaust leak but I am not so sure.

Any good techniques for pinpointing a manifold leak besides black scorching? Previous ones I have seen were super obvious to see, but it is so cramped under that car.

Thanks!
 

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#24 ·
Hey y'all here is an update:

  • exhaust manifold bolt torque was good but I reset the fit and torqued again anyways. No leaks or change.
  • did the same for exhaust flanges. No change- checked spark plugs on driver side. They looked like what I would expect. Threads had some wettness to them. See pic of #1 plug
  • put stethoscope to engine. Checked near crank, both heads, oil pan, etc. Results below:

  • Sound comes from front drivers side head area.
  • It is loudest (very loud) where the cylinder deck meets the heads on both the block and head side, up through the head, and on the cam cover where the chain goes both on front and bottom of cover
  • it is a rhythmic double-clack that seems more at cam speed rather than engine rpm (valve or lifter hitting hard? Broken timing sprocket or tensioner?)
  • it is moderately loud on top of cam cover near spark plugs, especially towards front, and bottom of head near exhaust manifold
  • near crank is much much much quieter, as well as oil pan and other side of engine
  • red on pics are loud areas, and blue is where it's quiet (relatively speaking)
So it seems like something in the valve train... I suppose it could also be the piston, cylinder or piston side of the road since it is loud at top of block where it meets the head. But the fact that it is so loud on the top of the head and cam cover rather than near the crank seems telling, as does the speed of the noise when it is off the startup high idle. Still no codes I've seen thrown.

This is still beyond my skill to fix, but I worry about finding a local shop to take it to. I've heard mix reviews about work like this from the dealer, not to mention the price. I'd rather work with an enthusiast Indy mechanic, but I've heard not many know how to rebuild or work these motors right.

Locally in Tucson it looks like there is Perfection Auto Works. The owner said they can do this type of work via email and he wants me to call him. Any experiences? Then there is Phoenix...

Thoughts? Appreciate any advice.

PS: shameless plug for that slick light from Harbor Freight.

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#27 ·
Since the actual pump side is completely isolated from the oily side of the engine - I wouldn't be concerned about particles in the oil. I might worry about chain-stretch due to the extra forces required to turn the broken pump. I'm making the WAG that it hangs off the end of a camshaft - and is turned by the rotation of the camshaft.

If you have a diagnostics machine capable of reading "Expected cam angle" and "Actual cam angle" that might give you a clue if anything inside the engine took a hit.
 
owns 2009 Porsche Boxster Base, PDK
#30 · (Edited)
I didn't use seafoam...

And didn't get any check engine lights, but not sure if there were any underlying codes

I used a stethoscope to isolate the noise to the pump area, and noticed a hard pedal. My local shop did the rest after towing it there. I began thinking I might do more harm than good.

Good idea on the cam readings. My mechanic said he was going to check timing and the oil filter just in case. I am almost positive that these pumps use engine oil for lubrication both for the bearing or bushing as it were and to lubricate the shoes that ride along the pump housing..