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Discussion Starter · #1 ·
Hi,
for the past year or so, my 2003 WRX (blob eye) has had an issue where on a cold start, it will make a knocking sound which sounds like its from the left side of the engine. After idling for a little bit, driving a few hundred meters, then stopping and starting the car it goes away. I believe it also goes away on its own without restarting the car if given a little while longer.

There sounds almost like a belt squeal sometimes as its restarted as the issue fixes itself. The car then drives normally once its been restarted.

Here's a video of it: (207) ej205 w avcs knocking/tapping sound on cold start, wobbly pulley? - YouTube

I also noticed today the crank pulley appears to be slightly wobbly, however i'm not sure what's normal. The video appears to stabilise the movement somewhat, it looks more pronounced in person. The timing belt was only done around 10,000 KM ago, I think it was before this started.

My theories are:
  • crank has being worn down
  • loose timing chain tensioner
  • failing cam gear pulleys (as these were not replaced with the timing belt, mechanic said this particular model of ej205 had pulleys which always strip when being removed and advised that it's usually fine to not do them if they're not leaking, which they weren't).
  • dying AC compressor somehow causing issues?
  • early failure signs of oil pickup?

I'm really just guessing wildly here.

The motor itself is the ej205 with AVCS, has a few bolt on modifications I've done over the years, mostly before this started. Original motor the car came with, 250,000 KM and change. Car was e-tuned, I think by boosted performance? It was some famous forum e-tuner.
  • STI injectors
  • 255 walbro fuel pump
  • silicone turbo inlet
  • triple pass mishi radiator
  • MAC 3 port EBCS
  • 3 inch TBE (x-force varex)
  • 3 port catch can

after the noise started
- process west tmic

There may be a few other things to I'm nothing of.

Anyway, does anyone have any ideas for what issue this may be, or what I should do about it?
The car runs great once warm. I do drive it pretty hard but I'm generally pretty careful with letting it warm up first.
I'd like to prevent any catstrophic engine failure if that's what this noise would suggest will come.
 

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Discussion Starter · #2 ·
it doesn't do this every day either
just started it and drove a few minutes, there was no knocking sound
it seems to be more likely to occur the longer the car sits without being driven, and i do drive it most days
 

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I would take apart the timing components + balancer to see if they're loose. It doesn't sound like it currently has any internal issues, but I would fix this before it does turn into that. Taking off the balancer and components takes 30 minutes if you aren't experienced, under 15 if you are.
It sounds very similar to this.
 
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