The swirl may be nothing. There can be a bit of 'color' in the oil what looks as best I can...

I’m posting "my list" today. This is item #2...

Car:
1999 standard Boxster
5 speed manual trans
Miles = 32,000
Pleasure car driven couple times a month. Oil is changed annually, usually approx every 3,000 miles. I use Mobile 1 0/40

Issue:
When I'm driving and under "neutral throttle" I get this buzzing around 2,800 RMP. If I hover around this speed at neutral throttle (neither accelerating nor engine braking) I can make this buzz constant. I originally assumed for a while it was just a frequency thing at that RMP that was making some shield or something rattle…
On engine braking I get a small buzz as the needle is falling through the 3,200 RMP range. Between say 3,200 and 3,000.
When the engine is under load (hard acceleration) I can sail through the 2,800 RMP zone with no buzzing at all.
When I’m driving very slow and shifting slow and easy I get the sound off and on as I lift the throttle slowly and again apply throttle after a shift… When doing this slowly, I get the sound as I gently pass through the “neutral throttle” zone.. Usually when babying during warm up.
Issue is same on cold driving and fully warm engine.
NOTE: When I am parked and in neutral gear and I just slowly apply gas, I get the rattle, but only for a short bit as the needle rises near 2,800. I can hold it at 2,800 in this situation and it will not buzz constantly like when I’m driving.

I had a very reliable indi look at the car and they said it was probably the vario cam system. Said that it is probably “engaging / doing something” at that point in the rev range and somehow is allowing temporary slack in the chain. “Under load (acceleration), there is added tension taking up the slack…” Was told to avoid hovering in that zone / accelerate through and address it at next major service as it would not be a cheap investigation (cam cover removal…).

I hope to drive the car five more years (approx 10K miles) and then do a ton of work at the 15 year / 45Kish miles mark. However, I hate to ignore this as I know with certain BMW models, the chains can cause major issues when they start losing tension… Plastic rails inside break and its downhill from there. NOTE: This has been doing this for probably at least 8K miles / several years. I did do an oil analysis one year ago that came back good. Was told Silicon was high but probably not abrasive as wear metals were low… Was told to check air filtration system (looks ok to me)…

Thoughts? Tensioners? Vario Cam issue? I do have a cam hold down tool and have pulled/resealed a cover before (broken plug tube pieces inside), but dont really want to go through the hassle just yet. FYI, I did a very slow and careful job on that so dont think I messed anything up and I think it was doing this before anyway, I just did not pay good attention at that time... FYI, never rand the car until I pulled the cam cover and got the broken tube pieces out....

Im pretty sure IMS would be rattling at all rev ranges and would have “gone” long ago… : )

I'm no expert, but I think it is a normal vibration. I have the same, and some say it can be lessened with new motor mounts. I think it is some sort of harmonic resonance, and I have sort of obsessed about it.
I have noticed that it is much more prevalent in 5th and 6th, making me think it is related to the transmission. I haven't looked at a schematic of the tranny, but my guess is that the shaft related to 5/6 is resonating with another engine part/accessory.
don't take my word as the final say. I'm pretty new to the Porsche scene, and there are a lot more experienced people on this site than I. I hope it alleviates some fears, though.

I do have the original motor mount. Everything in the car is stock / original.

Quote
bnsc100
I’m posting "my list" today. This is item #2...

Car:
1999 standard Boxster
5 speed manual trans
Miles = 32,000
Pleasure car driven couple times a month. Oil is changed annually, usually approx every 3,000 miles. I use Mobile 1 0/40

Issue:
When I'm driving and under "neutral throttle" I get this buzzing around 2,800 RMP. If I hover around this speed at neutral throttle (neither accelerating nor engine braking) I can make this buzz constant. I originally assumed for a while it was just a frequency thing at that RMP that was making some shield or something rattle…
On engine braking I get a small buzz as the needle is falling through the 3,200 RMP range. Between say 3,200 and 3,000.
When the engine is under load (hard acceleration) I can sail through the 2,800 RMP zone with no buzzing at all.
When I’m driving very slow and shifting slow and easy I get the sound off and on as I lift the throttle slowly and again apply throttle after a shift… When doing this slowly, I get the sound as I gently pass through the “neutral throttle” zone.. Usually when babying during warm up.
Issue is same on cold driving and fully warm engine.
NOTE: When I am parked and in neutral gear and I just slowly apply gas, I get the rattle, but only for a short bit as the needle rises near 2,800. I can hold it at 2,800 in this situation and it will not buzz constantly like when I’m driving.

I had a very reliable indi look at the car and they said it was probably the vario cam system. Said that it is probably “engaging / doing something” at that point in the rev range and somehow is allowing temporary slack in the chain. “Under load (acceleration), there is added tension taking up the slack…” Was told to avoid hovering in that zone / accelerate through and address it at next major service as it would not be a cheap investigation (cam cover removal…).

I hope to drive the car five more years (approx 10K miles) and then do a ton of work at the 15 year / 45Kish miles mark. However, I hate to ignore this as I know with certain BMW models, the chains can cause major issues when they start losing tension… Plastic rails inside break and its downhill from there. NOTE: This has been doing this for probably at least 8K miles / several years. I did do an oil analysis one year ago that came back good. Was told Silicon was high but probably not abrasive as wear metals were low… Was told to check air filtration system (looks ok to me)…

Thoughts? Tensioners? Vario Cam issue? I do have a cam hold down tool and have pulled/resealed a cover before (broken plug tube pieces inside), but dont really want to go through the hassle just yet. FYI, I did a very slow and careful job on that so dont think I messed anything up and I think it was doing this before anyway, I just did not pay good attention at that time... FYI, never rand the car until I pulled the cam cover and got the broken tube pieces out....

Im pretty sure IMS would be rattling at all rev ranges and would have “gone” long ago… : )

or an exhaust hanger, even a brake rotor splash shield, something along these lines responsible for the noise.

Based on the info you posted, the symptom/behavior doesn't suggest a VarioCam solenoid/actuator problem to me. I just went through these on my 02 and the symptoms were the sudden appearance of a very lumpy/rocking idle with a check engine light and error code P1341 (iirc).

However, the failure at least in my car's case was intermittent and the techs tell me most are intermittent, at least at first. Upon clearing the error code and driving the car again the engine ran ok, for a while. Also, once above idle the engine ran just fine, though I was a bit apprehensive about driving the car with the engine's VarioCam system acting up. The spectre of total engine failure due to possible loss of proper camshaft chain control was in the passenger seat.

The solenoid/actuator can be tested to a pretty high degree of confidence with the proper Porsche diagnostics computer by the tech manually triggering VarioCam solenoid/actuator activity and noting the sensor (camshaft position) readings and O2 sensor readings.

Not sure how beneficial a visual inspection is. First it is expensive to tear down the engine enough to even see the solenoid/actuator area. Even then there is not much to see. I have both the old solenoid and the old actuator and one can't tell anything's wrong with either one. Both have their details/complexities buried inside their sealed housings.

(A partial tear down might be called for though if an inspection of the oil filter housing/filter element found any signs of chain tensioner/guide composite plastic. In this case while the solenoid/actuator was still functioning correctly the guides/rails are coming apart and there could be something to see.)

BTW, if the solenoid/actuator test flags the solenoid my Porsche techs tell me that both the solenoid and the actuator should be replaced. The solenoid requires the camshaft cover be removed but the actuator requires the cams be removed, so the actuator R&R costs more in labor (about 5 hours more) and then there is the actuator part cost (approx. $800). The camshaft cover bolts are replaced too along with some other stuff.

To reinforce this both need to be replaced business, what happened is the tech did the tests and confirmed the problem resided in the passenger side VarioCam solenoid. I learned afterwards that the SOP is to replace both the solenoid and the actuator based on the experience of these techs that almost invariably both are bad. (I believe what can happen is the solenoid starts acting up and causes the actuator to activate/deactivate over and over again. Over time this wears out the actuator. The solenoid is replaced but then after the proper functioning solenoid is in the engine the worn out actuator becomes apparent.)

But for some reason I was not given the info about replacing both items. I was told the solenoid was the culprit and of course I gave permission to replace it. I got the car back and during a shakedown drive the symptom appeared again and the check engine light came back on. Same error.

I took the car back and was told that it is standard procedure -- based on the experience of the techs -- to replace both items. However, as I mentioned above I was not given the choice. I do not know why was not given the choice. Had I been given the choice I would have elected to have both replaced. I mean I trust the techs who work on my car. If they advise me both items need to be replaced I'm going with their recommendation. If I didn't trust them then I would not even have the car there for any work/service. Anyhow, the service department accepted responsibility for not giving me the choice. I was charged for the actuator part cost, and the extra labor to get to the actuator, but the labor and parts that were needed to get to the point at which the solenoid was accessible was absorbed by the service department.

Anyway, as I mentioned above based on what you posted VarioCam solenoid/actuator or some other chain drive component (tensioner for instance, or even IMS bearing) doesn't in my opinion seem like a reasonable explanation for what you are seeing/hearing/experiencing.

With no other symptoms, no signs of more serious engine distress, the buzzing I think has to be something external to the engine. With the car on a lift and with the proper setup the engine can be rev'd and the underneath of the car checked (listened to) for where the noise might be coming from. Of course, first the tech would use a stethescope to ensure the noise was *not* coming from inside the engine, from any of the various trouble-prone spots.

Sincerely,

MarcW.

I did my first DIY oil change on the car approx 2 years ago / 7,500 miles ago. Again, annual changes at approx 3,000 miles. I did see the "caramel swirl" in the oil. Noticed it more when I was dumping my large drain pan into milk jugs for disposal.

At the time I had no idea what it was and it was the first DIY I had done since watching Dad as a kid... I only recall it after recently reading about the chain guide "break-in" and that it can produce some brown residue. At that point my car probably had 25K miles give or take a few thousand.

Not sure if platic shows up in oil analysis. Never found bits in the filter. Have never dropped the pan and probably wont, as I think that would be overkill given the evidence. Yes?

Quote
bnsc100
I did my first DIY oil change on the car approx 2 years ago / 7,500 miles ago. Again, annual changes at approx 3,000 miles. I did see the "caramel swirl" in the oil. Noticed it more when I was dumping my large drain pan into milk jugs for disposal.

At the time I had no idea what it was and it was the first DIY I had done since watching Dad as a kid... I only recall it after recently reading about the chain guide "break-in" and that it can produce some brown residue. At that point my car probably had 25K miles give or take a few thousand.

Not sure if platic shows up in oil analysis. Never found bits in the filter. Have never dropped the pan and probably wont, as I think that would be overkill given the evidence. Yes?

describe it as some sign of metallic sheen. This is made up of very fine bits (particles) of metal, aluminum (better be!). Some of this is normal. If you dip your fingers into the stuff you can't feel anything cause the metal particles are so small/fine.

Bigger bits of metal, ferrous metal, or pieces of composite plastic (caramel colored or almost black) is not normal.

Plastic or anything derived from hydrocarbon I don't think shows up in oil analysis since when heat is applied plastic breaks down into well hydrocarbons.

Metals show up: ferrous (iron), non-ferrrous (aluminum or bearing materials (copper for example)). Silicon or silica is dirt (dust). Phosphates is coolant. Oh and water can show up.

Now it takes a bit of practice in viewing used oil too. The caramel swirl might have been the normal stratification that used oil can develop if it sits a while. The oil is contaminated with mainly water and unburned gasoline and these tend to come out of suspension as the oil sits.

No need to drop the pan at this stage.

If you want you can remove the oil filter housing and pour the oil out into a clean drain pan and see what you find. Chances are high you'll find nothing alarming. But it is a good check to make if the noises are coming from inside the engine.

Sincerely,

MarcW.