Knock knock knocking will it make me poor.

[Mig]

Knock knock knocking will it make me poor.

Hey guys, I've had my 01 300gt for about 3 months now. When it's warming up and I'm driving at about 1800-2000rpm there's a slapping sound coming from the engine. It does it in neutral also and the revs will drop about 500rpm when the noise occurs. Once cars hot it goes away while driving but will do it briefly at 1200rpm in neutral. Initially I thought it was a belt as it's quite a slow noise unlike lifter or rod noises which go in time with the engine speed.  I've found a clip on YouTube of the exact noise here, anyone experienced this before? 

 

[Mig]

It also only does it under light load. For example doing 50km with revs at 1500rpm then giving its medium throttle to speed up to 65km but not allowing the transmission to kick down. As the revs get to 1800rpm the noise occurs until passed 2000rpm. Usually I give it more gas to kick down a gear to get it out of the noise zone as it sounds like the car has eaten a bag of bolts. Once it's fully warmed up the noise disappears. 

[Rhinorebel]

Doesn't sound internal. It sounds like a physical slapping on the outside of the engine. Like belt on a broken piece of plastic or rubber that once warm, moves slightly so it doesn't touch???

[Mig]

Yeah that's what I thought too. Sounds like it's coming from under the plastic cover so will take it off and see if there's anything obvious hitting anything. 

[conan7772]

checked the fans ?

maybe a cracked blade

[Mig]

Good idea. I'll check that also! Found 2 clips on YouTube now with the same problem 

[Mig]

Not fan.....

definitly related to motor being in warmup mode. It's weird as hell. 

[Mig]

Engine also pinks. And it's running on 98 octane. 

[V35_Paul]

"Was the timing chain, replaced it with a new kit and it fixed the problem. Caused by not changing oil regularly."

 

That's what the guy said in the clip in the comments