audi49

I've searched this forum and the web regarding the below, but haven't convinced myself that what I heard was normal or not. Having said that... here's my situation...

Test drove a 986 Boxster S recently. The car was great, except I was bothered by a somewhat mechanical-sounding whine around 2800 to 3000 rpm (all gears, and in neutral) coming from the engine area (from inside the car, top up). I noticed it right away and frankly it was somewhat annoying (but only near that rpm).

I'd chalk this up to being 'normal', but I drove another similar Boxster S (twice) a couple weeks back and I was only impressed by the engine noises... I don't recall hearing anything like this on that car.

(For those that may have experiences with a 944, the sound is similar to that made by a balance belt shaft that is not correctly tensioned).

The following youtube video sounds real similar (even though this is for a new gen Cayman... but same sound I believe).

Any thoughts on whether what I experienced is normal? What could be causing it if not normal? I'm thinking that maybe variation in engine tolerances is contributing to differences in the two cars?...

Macster

Not normal as your experience with a 2nd car confirmed.

It engine speed related could be a couple of things. My Boxster was pretty good about not making any engine noises but once I heard a low volume/low frequency noise which proved to be from the water pump. The noise was present at cold start so I removed the serpentine belt and started the engine and let it idle long enough to confirm the noise was not present. Then I checked all the accessory drives for play. Only the water pump had any. Not much but it had some.

With my Turbo I heard as best I could describe as a "dry bearing" sound. Turned out to be a bad idler roller bearing. Some good amount of time later and thousands of miles later, I heard an intermittent faint chirping noise. Almost believed it to be my imagination. (My hearing's not so hot.) But had the car in a tech confirmed the noise. Proved to be yet another bad idler roller bearing. I had all replaced the 1st time so this means one of the new ones went bad. But way after any warranty coverage on parts/labor had expired.

Engine tolerances have nothing to do with the noise. If it is not an idler/tensioner roller bearing or a water pump (or other accessory drive) making the noise, this raises the possibility the noise is coming from inside the engine. This can be from a noisy (and soon to fail perhaps in spectacular and expensive fashion) the (infamous) IMS bearing.

With the car in the air and someone working the throttle to obtain/hold various RPMs a tech under the car can almost certainly determine if the noise is coming from inside the engine and if so where. Knowing from where then helps him make an educated guess as to what may be going on.

If the noise is not coming from the engine perhaps it is a drive train related? This opens up the possibility it is coming from the transmission, differential, or a wheel bearing. My Boxster has a rear wheel bearing go bad at around 90K miles. I could only hear it after I had new tires fitted. Even then hard to pinpoint which corner of the car. Shop owner had me road test the car and asked me my opinion. I told him which rear wheel and it so happens that was his diagnosis as well. The bearing was replaced and the noise was gone and remained gone for over 200K miles.

Tires can make considerable noise as they wear and get hard from heat cycles. But generally they are noisy at speed.

Blah blah blah...

My advice is to skip all the above and just cross the noisy Boxster S off your list of candidate cars. There are I'm sure a number of other cars that aren't noisy. You should seek out one of those.