Growl noise from under the bonnet when accelerating.

[Ehu]

I have a 2005 CLK270 CDI Elegance A coupe. It`s done 75000 miles. When I need revs e.g. starting off on a hill, or when I suddenly need to accelerate, I get a growl from under the bonnet. When I reach the speed I`m after and back off the accelerator a little, the growl stops. The car is running perfectly ok outside of this noise. Any ideas?

 

[mattkh]

At what mileage did you first notice this growl..??

 

[oigle]

Engine mounts....the 270 is very hard on them.

 

[Ehu]

I`ve only had the car since June 2020 and it came with this noise from under the bonnet. It`s not a worrying issue, I`ve done 8,000 miles in it to date.
It`s hard to describe the noise, it`s not a metal to metal or anything like it, I`m no techie but I thought perhaps it was like blowing from the manifold ??
All I can give you is that it`s when I accelerate the noise starts and as I said earlier, when I reach the speed I want and back off the throttle a little, it stops.

 

[mattkh]

..... it came with this noise from under the bonnet.

Thanks.
Do you get the noise if you rev the engine up with the car stationary..?

 

[Ehu]

I`ve just tried it and it`s difficuilt to say, because the engine isn`t under any load with it not moving.

 

[mattkh]

I`ve just tried it and it`s difficuilt to say, because the engine isn`t under any load with it not moving.

Thanks. That rules out any intake hose split.
As engine mountings have been mentioned, it seems probable that the sudden jerk when accelerating creates a gap in the exhaust manifold to cause the growling.

 

[horatio]

Have you checked the pulleys & belt tensioner?

My engine mounts were shot around 80-90k. Get someone to rev it and you’ll probably see the engine shake when they let off.

 

[Ehu]

Thanks for the advice everyone, I appreciate it. It gives me a couple of new areas to consider.

 

[mercmancdi]

Has it done it since you bought it. Or just started doing it.

 

[Ehu]

It`s been there since I bought it.

 

[mercmancdi]

If you are on a level rd and push throttle slowly do you get the noise or only when you push hard to overtake or get away quickly for example, if I had a independent exhaust centre near me if I were you I would get them to put it up on a lift and check all exhaust joints and there are no poor exhaust repairs. It would be the cheapest check. I know you know this but if you drop the shoe on that car you will naturally get a power train type roar which naturally disappears when you lift your foot.

 

[Ehu]

It`s only when I push hard on the accelerator, as in needing revs to overtake or needing revs to pull away because I`m parked on a hill. Once I reach my required speed, I ease off the pedal and all`s fine. I`ll look into this exhaust check, thanks for the suggestion.

 

[Ehu]

I`m away for a few days now, but will look into all your suggestions when I get back. Thanks for the help, it`s appreciated.

 

[00slk]

Neighbours cat???