(I tried to search but couldn't find anything that fit my current situation)

My 04 with almost 100k is making this low grunting/growling sound throughout the entire RPM curve. At idle it runs a little rough, but smooths out as soon as I get moving. The noise gets louder as the natural sound of the engine increases with RPM. The noise just began yesterday as I drove back from a easy going roadtrip weekend to the mountains of NC.

Any ideas? I was hoping to get a head start on the diagnosis before taking it a shop in the next day or two.

Thanks

 

imma guess its Marbles in a Can.

 

it can also be a loose heat shield coming from your CAT area.

 

^lol yeah, well unless we get him to post a video or sound clip or a picture of the area its coming from.... we are really no help to him. I guess we have to play the waiting game for him to come back on and post a response.

 

Feed it.

 

alright.. so its definitely NOT a rattling sound.. its a rumble. no marbles in the can,. no loose heat shields.. its coming from the the engine itself. Pretend you take the sound of the revving engine and lower it an octave.. It starts quiet at low speeds and grows gradually with increased RPM's. Its like the normal vroom vroom, but sang by a bass, not an alto.

 

animal stuck under the hood?

 

Please give us the history on your car. The service it's had parts replaced. Type of driving it gets(long commutes, short trip), fuel used(reg or prem), ever flooded. Just any thing that you can add. What mods...

 

Well once you take the VFad off.. It gives your car a little throatier (bass) sound Which I like! w/ KN filter

 

When I bought the car in late 2007 the dealer had just rebuilt the transmission. Other than that there have not been any real problems, or much of a service record to speak of since Ive owned it. I've never driven it very hard, hitting red line once a week or so just for kicks. My racing days are over so Ive always taken it pretty easy in the 8. I put roughly 15k on her a year, driving a 50/50 mix of highway and city miles. I use high octane fuel for the most part, unless its sold out or Im low on cash. I flooded it once just days after I bought it, but that was 2 years ago. No mods, the car is completely stock.

Thats about it. The noise its making doesnt sound like anything particularly out of place, so to anyone who doesnt own an rx8 it probably sounds normal. It gives the engine note a more aggressive tone, but to me it sounds bad simply because it wasnt there until a few days ago.

you would think that if anything was really wrong with the car I would notice other differences, but everything else is fine (ie: performance, ride, vibration)

 

get a really long screwdriver . with engine running put the tip of the screw driver on the engine and the other end against your ear . go around the engine like this till you find the location of the noise . Be careful around the drive belts ...

 

Hole in exhaust or leaky gasket

 

If it's sort of a bubbling (which can be taken as growlling, but faint growling) noise, you can possibly have air in your cooling system. Search "Coolant Change" under the search (search titles only) and you should have a step-by-step DIY on how to bleed air out of the cooling system.

Also, if it's a sound that's unaffected by RPMs. It can possibly be the whirring from your transmission that you're hearing. I get the same sound and it goes away when I depress the clutch but comes back after I release.

The second scenario is pretty normal with this car. We have a rather loud Aisin transmission.