9A1 Valve Tapping Noise - New sound and won't go away after a spirited drive

Hey guys, As many of you know, I did a DFI conversion and GT4 engine swap in my 2006 Cayman S and it's been running beautifully. That said, a couple of weeks ago, my buddies and I went up to the mountains on a spirited drive and the car was great. Then when it got home, it sat for about a week and a half, which is a bit longer than usual, but nothing crazy. Then when I went to drive it to dinner about a week ago, it had a pretty loud lifter tick sound when it started up. I figured it was probably from sitting a bit longer than normal, but usually it can go weeks or even months without having a tick, so I thought this was weird. I drove it about 45 minutes to dinner in some traffic and a few pulls here and there and it drove fine, but I could hear the tick anytime there was a car next to me on the right side (dominant side that I hear it from). By the time I got to dinner, it wasn't crazy loud or anything, but it was still noticeable. Well, after a few more drives since and tightening the header and exhaust bolts (in case it was an exhaust leak), it still hasn't gone away. This engine only has about 20k miles on it. I'm just trying to get an idea of what it could be and if it's something I should worry about. I have no CEL and the engine still runs normally with no stumbling, misfires, smoke, etc. Thanks guys. Hopefully it isn't a big deal, but for now the car is getting swapped for the M5 in driving duty for a bit.

The origins of clicking sounds can be numerous. The fuel injectors click, a loose spark plug will and of course valves too. I ran my car last week without the engine cover on to coffee, top down. I heard way more mechanical noises than normal, and my car runs better than any I’ve ever owned. You state that the car runs nice, there are no lights, you didn’t say that it was leaking oil so I’m going to assume that’s good. It runs at the proper temperature and does not lose coolant. Just drive it, go enjoy it. You did all that work? Go love the car that’s my advice. PS if you’re running more than one bar off oil top, try bringing it up but myself? I always leave one bar clear from top level.

This is definitely a new sound and not injectors and spark plugs were recently torqued to spec (though I haven't checked again after the last drive) as I've been driving it for a while this way without hearing it. Also, the noise is more noticeable outside the car. It has zero leaks and oil was checked and shown to be dead in the middle on the display. It runs at normal operating coolant and oil temps (I have a display added to the sport chrono that shows me oil temp, pressure and coolant actual temp), oil pressure is about 2.5 at idle, 3-3.5 cruising, and 4-4.5 at WOT. I'm inclined to do what you said and just drive it, but I'm getting ready for a track event at Road Atlanta in November and I was hoping there wasn't something I needed to worry about since this car has to get me down there, survive a 3 day track weekend, then drive me back home. I will try to add a bit of oil and see if that helps too.

The parameters for good engine health have been covered and the car shows no symptoms. Just as a perfect sounding great “yesterday” engine can blow tomorrow so can a “ticking” engine run for years. To my ear it sounds like you want to go racing with no risk and that isn’t an option. If the only thing that will assuage your anxiety is no ticking at all you have to do a deep dive into the engine. If I was facing the same anxieties, I would go enjoy the car because all of the vital signs of the engine are good. It only makes sense to use it until and if it breaks and then figure it out from there. Perhaps others will have better advice, good luck ! Enjoy road Atlanta and report back on whether the road surface is very hard on your tires . I don’t live too far from there and that’s kind of a local lore that I read about.

You definitely make solid points and I certainly understand that tracking a car with zero risk is impossible. That said, going with a known problem is not super smart. You're right though, the vital signs are all good, so it's likely just fine and I shouldn't worry. Also, if there is something wrong with the heads/valves/cams and something does go wrong, I still have the perfectly good 3.4 DFI engine that is sitting in my shed on a stand I could pull parts from to fix it. I know I got the cheapest GT4 engine on the planet when I got it, so it's not like it's the monetary issue if it fails, it's more that it's a 20k mile 3.8L GT4 engine that would be off the road if it blows up. Unless it gets noticeably worse, I'll be going to Road Atlanta for it's second track event no matter what. The first one was an absolute blast in 2024, and that was with the 3.4 and Michelin PS4s and the wrong coilover springs. All that is improved now, so should be even better. Oh, and Road Atlanta was fine on tires the last time. This car has so much grip. I have Apex SM10s and GoodYear F1 Supercar 3 200TW tires now, so it should be even better, though with more power, who knows, LOL.

Good luck black knight, I hope you have a blast man.

A bunch of us have found loose exhaust manifold bolts on the 987.2, and that will cause a tick. The 981 has the same engine but they increased the torque spec for it. You may want to check that. If you do a search you can find some details.

That was actually checked as I thought it sounded like an exhaust leak. There were a few nuts loose on the headers and I tightened them all up as well as the ones on the connecting pipes to the back section of the exhaust . The gaskets weren't brand new when I did the GT4 engine swap, but they were new when I did the DFI conversion with the 3.4. They might need to be replaced again, so that is still a theory that makes sense. The 3.4 DFI engine would rattle those bolts out normally and when I did swap it to the GT4 engine, there were at least a couple missing entirely on both banks. Are we supposed to use any loctite on those?

No loctite , I don't think it'll hold with the heat there anyway. The 987.2 spec is 18 ft-lb but they upped it to 22 ft-lb on the 981. I used 22 ft-lb (it's the same engine and bolts) on my 987.2 but do NOT blame me if you try that and strip something. With a new gasket I found they'd loosened again after a few hundred miles. I retorqued them all to 22 ft-lb (loosen slightly and then torque) and they have not since moved. Someone else told me they had the same experience: retorque after driving a few hundred miles and then they stay put. You shouldn't need to replace the bolts, they are not torque to yield or anything.

The GT4 engine has nuts with studs instead of the bolts used on the 987.2 engine. That's probably why they increased the torque spec if I had to guess. I may try to replace the gaskets and I'll try the retorquing after some time and see if that makes a difference.

Nuts with studs is OEM on the 987.2 both for the manifold and the exhaust connection over the axle. Bolts would be a later modification probably due to rusted out studs being driven out and replaced.

The manifold is held to the head by bolts. 987.2 parts diagram:

Well, I did some more diagnosing today and I am really leaning towards a collapsed lifter due to some possible debris or gunk that doesn't want to clear. I used the stethoscope again and the noise is definitely coming from the valve cover area right above cylinder 1 (furthest forward on the passenger side/right side). I suspect that when the engine I got was in the accident (donor car) and it sheared the high pressure fuel pump off and got a hole in the valve cover in the back corner, there might have been some small debris that I didn't get cleaned up. Maybe it somehow got into the nearby lifter and isn't allowing it to fully pump up. Cylinder 3 sounds totally quiet and it was where the hole in the valve cover was, so I think I got all of that debris cleaned up. It seemed to be totally fine for about 6 months of driving it, but maybe the spirited mountain drive knocked something loose. In any case, it looks like the next diagnostic step is to pull the engine, remove the valve cover and check for lifters that press in with my thumb pressure and replace it if necessary. Timing tools don't seem to be too expensive at just under $300 or so and I should be able to just replace the bad lifter, so hopefully won't be too expensive to do that. Ugh, not what I wanted to discover though. Was really just hoping it was an exhaust gasket leak. Also, oil level is at the first bar below the full mark, so it's not low on oil.

Please do keep us informed on your progress... these sort of oddball things are always valuable info to have and to archive here.

Engine debris is a nasty thing to deal with.........The thread, inclusive of the 15 prior posts, makes no mention of a Blackstone, or other oil sample analysis, any use of drain magnets, oil filter disassembly, etc. being performed? Do you have a post mortem on this 'replacement engine' on the donor car that you're using? I would strongly suggest that before another "spirited drive day" that you have one of these performed. Also, a "spirited run" to me means a Sport + setting, which brings nearly a nearly full 'red line' shifting drive mode in the lower gear ranges, and potentially flat out in top gear for some period of seconds. After a several hours of 'track day' operations, upon getting home I'll do an oil/filter change to a non-racing oil.... or just an OEM rated oil for your engine/ Mobil 1 0W-40 /A40 in my case. I'm not discrediting a manifold bolt or lifter collapse issue.... but that is not the first place I would look. Perhaps I'm totally mis-informed, but I didn't want to assume. I almost always run an oil sample after every track day.... even a full Autocross day. Regarding an exhaust manifold leak, if you pull the exhaust manifold, an exhaust leak will leave a tell-tale heat signature mark on the manifold and/or the steel gasket. Next, I would slap a PWIS on the car and perform a shift and electronic engine code review.... sometimes CEL codes will not show, but could still be captured?.... next, a compression check... ? Thoughts deilenberger? With a 'suspect engine' and after a hard drive, an oil drain would have been a good idea..... shoulda, woulda, mighta?

Hello Leo, thanks for your input. So, the engine was opened up (oil pan off, both valve covers removed, no debris found anywhere other than on the surface of the cylinder head where the HPFP was and where there was a hole in the valve cover at the opposite end. Everything was cleaned thoroughly from what I could see. The engine was never run in the wrecked car after the accident and only in my car after it was swapped in. It ran for a solid 6 months without any issues, even with a spirited drive on the Cherohala Skyway and Tail of the Dragon, as well as other roads in the area. I have not yet taken the car to the track with this engine in it, and don't plan to until I find the issue and fix it. You're right that an exhaust leak would be a tell-tale sign, but there is a large flange on the header where it mounts to the head and I haven't yet removed the header to check under it.They are fairly new gaskets, but have been removed and reinstalled a couple of times. There are no engine codes shown in PIWIS and the engine still drives as smoothly as it did when I first installed it, which was the same as the 3.4L DFI engine that I replaced. Also, to respond to your message about the oil drain and a "shoulda, woulda, mighta?" comment, the car has not really been driven since I first started noticing the noise. Also, Changing the oil after every mountain drive is a bit excessive. The oil only has about 1000 miles on it or so. Not like it's been thoroughly used yet. I agree, that it is on the list of things to do before I drive it again though. The car is sitting on the lift for now.

Agreed on your oil change comment, for long range, road driving?. However, a "spirited drive" for me is multiple hours of continuously or nearly continuous driving as fast and as well as I can without putting it in a wall or a ditch... so mileage may not be that relevant? In saying that, it doesn't take long for bad things to happen, especially with suboptimal oil/lubrication under high G's or high RPM/load conditions, or both. So substantially, my comments are......"never mind".