Knocking noise when releasing clutch to move off

[Oatmeal123]

Hello again everyone,

I was wondering if you could assist me in figuring out the source of a knocking noise and what could possibly be causing it. 

I have a 2006 impreza 1.5 R, when I am releasing the clutch to move off from a stand still a knocking noise appears, as though the engine is tapping something in the bay.

I haven't been able to pinpoint the problem and recreate it everytime without fail. But if I am pulling off from a stand still then the noise could happen once quite loudly or 2 or 3 times consecutively but rather quiet. 

I usually move off at around 1,500 - 2,500 rpm (tis a baby 1.5  )

Dropping the clutch or doing my best to make the car jerk back and forth does not seem to produce the noise so I'm a tad confused to the analogy of a loose engine.

As odd an explanation as this is, would anyone have any insight as to a common problem associated with such a noise? 

thank you

 

[Steveuk260.Esq]

Subframe bushes is a possibility if it sound like a clank. its usually when moving from stopped in 1st gear.

[Oatmeal123]

I guess if anyone ever finds this, here was the solution. The engine mount behind the engine connected to the firewall was a tad loose. The bolt that squeezes it together wasn't tightened properly.