kingsmanexotics

So two weeks ago I turned on my R8 and I heard what sounded like a rattling from my engine, its a rapid and constant rattling.
The noise is there when the cold start and it gets worse when it warms up. the car also feels like there is a lack of power when accelerating.
I took it to the mechanic, he said the rod bearings are getting old although they aren't hurt that badly and he is unsure if it would make that noise.
He did say he found A LOT of carbon build up & that could be the issue.
Im getting him to replace the rod bearings anyway.
there's 60000 miles on it. Was gonna trade it for a 2017 and then this happened.. smh.

I guess my question is
Could a carbon build up cause what I'm describing?.. or am i out of luck
does anyone have any idea what it could be? or am i out of luck

kingsmanexotics

Sorry one more thing, engine light is not on.

Stevereddy

AudiAllTheWay

Rod bearings should last life of engine assuming proper oil maintenance and reasonable spirited driving. One suggestion idle engine and remove oil fill cap then idle should drop and sound odd due to loss of crank case vacuum seal, but if loud constant cyclic trunk monkey repeatedly tapping shiny metal with ball peen hammer sounds are heard then shut down and inspect for possible broken chain guide as cam adjuster may constantly compensate for excessive chain slack. This can produce no diagnostic code yet present a new audible rumble heard in cabin especially when stopped during daily driving. Slow carbon accumulation at intake valve inlet increases with mileage and eventually becomes required maintenance.

drexer13

First thing I would do is find someone with vagcom or obdeleven and scan it for codes, just because there isn't a light doesn't mean the computer hasn't picked something up. Next thing I would do is pick up a mechanics stethoscope and see if you can identify where the noise is coming from.

Stevereddy

plat27265

Rattling noises could be caused by crumbling Cat Converter or muffler guts. Loss of power may be caused by carbon build-up issues. How can your mechanic tell that your car's engine has carbon build-up issues? Did he use a scope?

His comment about rod bearings causing the rattling noise is suspect. Rod bearings do not make such noises. If the rod bearings fail, they just seize up. They do not emit rattling noises because even if they're worn down the tolerances are still quite small and tight. If you are diligent in changing your car's oil regularly, rod bearing last for a long, long, long time. Definitely not a 60k replacement part. Me thinks they're just trying to look for something to replace in your engine.

If you are planning to trade it in, save your money and not replace the rod bearings especially if it is not proven that they're the culprit. I would check out the cat converter or mufflers first.

drexer13

I agree that running it needlessly is not a good idea, and I absolutely agree the you should not be driving it. I don't agree that anyone should take a car to any mechanic or dealer without having some sort of an idea about what is wrong. I assume that because you came to a forum asking for help, you intend to figure out as much as you can on your own. If that's the case then I'm happy to help out as much as I can. If you don't feel comfortable trying to diagnose it yourself then your at the mercy of the mechanic you take it to.
Bottom line, any mechanic trying to diagnose the problem is first going to scan the car to see if it has any stored codes, then they will start the car to see if they can figure out where the noise is coming from.