Weird grumbling noise?

[jining]

Hey guys, so I just replaced my leaking radiator and fixed my leaky downpipes and finally thought the car was finally good to go...and literally the next day it starts making a weird knocking grumbling sound randomly when accelerating and sometimes I even can get it to happen at constant throttle. Its very odd and i can't put my finger on what it is, and it's hard to even describe...... any common issues that might cause a noise like this? No check engine lights. Could air in the cooling system cause this? Been like this for over a week though and seems to not be improving.

Thanks

[jining]

Could it just be the downpipes and high flow cats? Seems odd that this happens right after fixing pretty bad exhaust leak at the downpipes and radiator so I would think related to one of them.

[jining]

bump

[wednesday]

Is it possible to record this and post a video somewhere for us to listen to it? Try it in higher gear so the engine sound is lesser than the culprit in question..

Groaning can be a wheel bearing..
knocking sound at start off or between gear changes can be control arms or really bad mounts..
tensioner/idler bearing can make a racket in it's own way if that is on it's way out..

How was the exhaust fixed? Could something to fix be rubbing somewhere? Loose plastic maybe?

It is not uncommon to uncover an existing sound when we fix something that was louder perhaps.

[jining]

I have tried but the noise is pretty difficult to hear and reproduce, I'll keep trying. Seems to be something in the engine, I clutched in and revved and could get it to make noise at a stop...but that was only once. Most of the time its light throttle or when I let off the throttle. Also, I have no check engine lights. The exhaust was fixed using a larger clamp, it may be something rubbing, I was thinking that. I will change the oil tomorrow and check. Thanks for the help.