Deep grumble @ 2.5-2.8k revs

[Barney626]

So just reattached the middle hangar on my exhaust and have started getting a deep rumble/grumble when accelerating between 2.5k and 2.8k revs.

Only happens when actually accelerating (Not while revving with clutch in or in neutral), in all gears and doesnt seem to be affected by speed (Sounds the same at any speed).

Sound is similar to driving along the painted line at the edge of the road.

No noticable wheel/car shake/vibrating.

Best Ideas I've come up with:

Exhaust join (Would have thought it would make the sound while revving if this was it). Looks like the join between my silencer and back box is blowing (Black deposits around it) but it's been like this for a while.

Cracked rim. Front rim went into a curb at 15mph in the winter thanks to some nasty ice. Ended up getting subframe replaced and now have a slow puncture. Fairly sure the puncture is rim related as had two sets of tyres on it which both did the same 10psi per week loss.Would this make the noise?


Only other thing I've done to the car is bleed brakes but don't see how that could affect it.

Any ideas what it could be?

 

[Benno]

Mine has a slight flat spot at that point which makes a slight noise change, could it be that?

 

[Barney626]

Mine has a slight flat spot at that point which makes a slight noise change, could it be that?

Fairly sure it isnt. Definitely never sounded like this before and it's very defined. I don't think its 'meant' to sound like this...

Cant get a good video of it to show what it sounds like really

 

[Barney626]

So still stumped on this.

How does the rear hangar normally get attached? I literally just put a bolt through it. Metal on metal contact so wondering if it's meant to have some kind of damping material and that's what is causing the noise?

 

[tomislavp4]

If you hit the cat from below, do you hear anything loose inside?

Mine sounds strange at 2600-2800 too and according to the place I usually leave my car at, the cat needs changing. May be the same issue.

 

[Barney626]

If you hit the cat from below, do you hear anything loose inside?

Mine sounds strange at 2600-2800 too and according to the place I usually leave my car at, the cat needs changing. May be the same issue.

Will try that.

Been told my car smells like gunpowder or fireworks by a friend who was following me so possibly cat related?

 

[tomislavp4]

Will try that.

Been told my car smells like gunpowder or fireworks by a friend who was following me so possibly cat related?

Try it, we might have the same issue. I also noticed higher fuel consumption lately, like 10% higher. Have you noticed this as well?

 

[Barney626]

Yep I seem to have gone down from 23mpg to 20.7mpg

 

[Barney626]

Tried banging both cats and no rattling/loose noises.

The join between my middle silencer and backbox was blowing a bit so pasted that up but still have the noise.