2006 997.1 C2S rattle around 3000rpm

[garrarni]

Hey. New here. Tried for some help on 911uk in the past, but couldn't get help on one particular thing that is bugging me on my car. Thought I'd see if a more global audience could give me a hand / advice.

Many thanks to all for looking. :)

My car develops a metallic noise / rattle as it accelerates through 3000rpm. It does this in gear and also in neutral. It doesn't happen when cold, but starts as soon as the water temps start to build. You can drive through it to some extent - ie accelerate quickly through the 3000rpm barrier (it goes by about 3300rpm) or change up below 3000rpm, but it is a little annoying.

Through my local specialist, we have tried the following:

Change exhaust (it has PSE) and cats - no difference
Change oil pressure relief piston - no difference
Checked heat shields - all seem tight
Change ancillary oil pump - no difference

I've read that 997s can do this at around 3000rpm as it is where the variocamplus changes over, but no idea if this true or an excuse.

There is a very mild 'lumpiness' to tickover when warm (sparks, coils, MAF etc. all new.) Potentially the variocam stuck on the longer stoke...?

Really just clutching at straws here, but anyone that may know a bit more would be much appreciated

[JFP in PA]

Hey. New here. Tried for some help on 911uk in the past, but couldn't get help on one particular thing that is bugging me on my car. Thought I'd see if a more global audience could give me a hand / advice.

Many thanks to all for looking. :)

My car develops a metallic noise / rattle as it accelerates through 3000rpm. It does this in gear and also in neutral. It doesn't happen when cold, but starts as soon as the water temps start to build. You can drive through it to some extent - ie accelerate quickly through the 3000rpm barrier (it goes by about 3300rpm) or change up below 3000rpm, but it is a little annoying.

Through my local specialist, we have tried the following:

Change exhaust (it has PSE) and cats - no difference

Change oil pressure relief piston - no difference

Checked heat shields - all seem tight

Change ancillary oil pump - no difference

I've read that 997s can do this at around 3000rpm as it is where the variocamplus changes over, but no idea if this true or an excuse.

There is a very mild 'lumpiness' to tickover when warm (sparks, coils, MAF etc. all new.) Potentially the variocam stuck on the longer stoke...?

Really just clutching at straws here, but anyone that may know a bit more would be much appreciated

As weird as this may sound, try taking off the serpentine belt and run the engine (very briefly) to see if the sound goes away. If it does, check your water pump and other pulleys for looseness and/or noise.

[Mijostyn]

Hi Garrarni, Welcome! Your rattle has a resonant frequency that is being excited by the engine at 3000 RPM and is modified by heat... things expanding and contracting. As you have discovered these rattles can be tough to locate. Since I got a set of these,

http://www.jsproductsinc.com/Store/Product/11331 I have never been stumped. You have someone control the car and you slowly wave the microphone around following the volume of the rattle. As you get closer to the rattle the volume increases. It will lead you right to it. No guessing, which is what everyone has been doing. This same company makes Chassis Ears. Say you think you have a bad wheel bearing. The set consists of 4 microphone/transmitter units each with a unique radio frequency. You place a microphone by each wheel and take the car for a ride. You toggle each microphone and the one with the loudest noise is the bad wheel. You can also find all manner of rattles, creaks whatever. Your friends will be amazed!! Worth every Shilling.

JFP you REALLY need one of these. If you don't like it I will buy it back from you.

Edited January 19, 2014 by Mijostyn

[garrarni]

Thanks for the replays so far. Will pass on to mechanic as it is beyond my skills

[JFP in PA]

JFP you REALLY need one of these. If you don't like it I will buy it back from you.

We have something that is like their chassis and engine ear combination kit, but from a different manufacturer. They are extremely useful for isolating noise sources, but the DIY'er can do something similar with a simple doctor's stethoscope for a lot less money. Not as elegant, but very practical for around $15:

[Mijostyn]

JFP, that is a stethoscope your 3 year old would use. Mine cost $148.99. The way you use it as you suggest is to touch the edge of the bell to the part you want to listen to, not the diaphragm. It is useless for listening through air which is what makes the Engine Ears special and cheaper than my Littmann Cardiologist!

Edited January 22, 2014 by Mijostyn

[JFP in PA]

JFP, that is a stethoscope your 3 year old would use. Mine cost $148.99. The way you use it as you suggest is to touch the edge of the bell to the part you want to listen to, not the diaphragm. It is useless for listening through air which is what makes the Engine Ears special and cheaper than my Littman Cardiologist!

True, but for the average DIY fix where it would only be used once or twice in its life, sometimes a cheaper but not as capable alternative fits the budget better.

[Mijostyn]

JFP, that is a stethoscope your 3 year old would use. Mine cost $148.99. The way you use it as you suggest is to touch the edge of the bell to the part you want to listen to, not the diaphragm. It is useless for listening through air which is what makes the Engine Ears special and cheaper than my Littman Cardiologist!

True, but for the average DIY fix where it would only be used once or twice in its life, sometimes a cheaper but not as capable alternative fits the budget better.

Absolutely! I like to put it out there because after several rattle disasters of my own like the poor fellow above, who got a new exhaust, all shops should have one and many people do not know this technology exists. The dealer I used 20 years ago had one and bailed me out after having spent... two weeks chasing a rattle in my glove box that turned out to be a plastic panel on the bottom of the car. All shops should have one as I am sure they get at least a few rattle complaints and there is nothing like a happy customer. These rattles can be like a splinter...in your brain. I use mine more frequently on new vehicles but with three other cars to maintain (wife, daughter) it gets used about once a year. BUT, it saves me HOURS spent chasing hard to find rattles and time is invaluable. The Engine Ears are much less expensive than the chassis set up and are used differently. As an example it is much better at finding rattles inside the car as opposed to out side. Rattles can be ventriloquists. It can be very hard to find them. This device will lead you right to them down to the millimeter.

[garrarni]

been all over engine with some form of mechanics stethoscope - not water pump etc.

noise coming from area of main oil pump. could this be causing it? pressure etc all ok. oil changed regularly.

[JFP in PA]

been all over engine with some form of mechanics stethoscope - not water pump etc.

noise coming from area of main oil pump. could this be causing it? pressure etc all ok. oil changed regularly.

Only thing that I can think of off hand is the oil pump's pressure regulating spring and valve; some M96 cars have had issues with the spring and have had to replace it. Items #5, 25, and 26 below:

[garrarni]

Cheers JFP, but already replaced, with no luck.

rhinking about the whole thing. parts aren't too bad, but no idea what the job would involve time/cost wise from the mechanic

[bigscotia10]

Hey garrarni, did you ever find out what the issue was?

Thanks a lot!