Until now I have had no issues with my 2003 Prado but I recently noticed a knocking noise coming from the engine when it is cold. I am hoping someone with a 120 4.0l V6 could confirm if this is normal.
My car has done 137,000Kms.
If I start the car with the bonnet open (easier to hear the noise) when the car is cold, and I rev it between 1500-2000 rpm I can hear a knocking noise coming from somewhere in the engine. Because this engine has no throttle cable I cannot rev the car and listen in the engine bay at the same time.
This is not the normal ticking noise from the exhaust manifold, nor is it a ping - it resembles more like a dodgy big end or small end bearing but I have never heard of these engines suffering from premature big end wear. The other thing I was thinking is the VVT cam adjuster may be faulty.
If anyone can confirm or deny if their 120 petrol engine makes this same noise I would really appreciate it before I spend money taking it to a mechanic.
Oh yeah, it has been serviced regularly at the correct intervals.