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Getting a fairly deep rumble, which sounds like a blown exhaust, from my boxster s. The only thing that makes me think it's not the exhaust is that it only occurs between 2700 and 3000 revs, above and below that it sounds just fine. Cant tell exactly where its coming from, other than it's at the back of the car.
Its not going to be the dreaded ims bearing failure as that was done only 3500 miles ago. No engine light warning on. Any other ideas of what it could be?
Chances are it's the exhaust or a baffle in it (which might well only vibrate at certain rpm).
Struggling to think what else it could be - wheel bearing (should be noisy all the time)?
Gearbox (Is it the same in all gears)??
Watching with interest as I'm hoping to get a 987 later this year as a fun car.
It's not a wheel bearing as it makes the noise when revving the engine when stationary. And it happens in every gear, always exactly at the same point on the rev range.
I'm going for a baffle collapsed.
Probably it's loose, or there is a baffle that's corroded inside one of the boxes as Sharkbait says. I've had this happen. Get under it and hit the boxes with your fist.
Does it have some clever valves that open at certain revs to increase/decrease compression or efficiency or noise reduction. If a pipe into the exhaust is blocked off and then opened it would explain the consistent noise. IANAM.
I have no idea what a baffle is! Is that going to mean a new exhaust system, or Is it just a replacement part?
Baffle is an internal part of the exhaust that moderates the noise, found in the boxes of the exhaust.
New section of exhaust likely to be needed if that's the case.
Google images or wiki will give you some pictures and a better description.
Loose heatshield? Might be more of a rattle. If you block the tailpipe can you hear exhaust escaping from anywhere along the joints or boxes?
It sounds like, as above, a lose baffle or a corroded section of the exhaust, exhausts are quite modular so you can replace a mid box or a back box or a section of pipe.
However, if it is corrosion in one place, most OEM exhaust are made from really cheap mild steel, so there's likely to be corrosion in other places too which might soon need replacing.
Best bet is to jack the car up and have a look, as if other sections are on the way out, it would be cheaper to replace multiple sections at once rather than pay to replace them one section at a time.
[I]However, if it is corrosion in one place, most OEM exhaust are made from really cheap mild steel[/I]
I thought the opposite, I'm sure there are plenty of 10-15 year old cars running on their original exhaust, once you replace with whatever pattern part KwikFit have on the shelf it seems to need patching or replacing every 2-3 years.
OEM replacement or quality stainless exhaust seem to be the best option but lots more expensive.
Original Porsche exhausts always used to be very high quality. My 1986 951 still has a lot of the original system. The exhaust on my 1989 944 outlasted the body shell.
But yes sounds like a baffle unless as mentioned it has some kind of variocam or varioram. Porsche Club Gb have a very helpful forum, probably worth a visit.
@tpbiker - go and get an account on the boxa.net forum, lots of helpful people there.
http://www.boxa.net/forum/forum/66-987/
Think of this as an opportunity to improve the sound your car makes 😁
Does it have some clever valves that open at certain revs to increase/decrease compression or efficiency or noise reduction. If a pipe into the exhaust is blocked off and then opened it would explain the consistent noise. IANAM.
I’m going for this. If it has a flapper it may be stuck. Then again you’d notice the noise, it being slightly louder etc.
Worth a look.