[gtrjohn.91]

Hey folks!

I bought an R33 GTR recently and I'm having trouble diagnosing a sound. Here's the video link:

Please ignore the rattle, that's my window.

The initial ping happens only once whenever I tap the gas suddenly at low-rpms. Slowly revving it is fine. Hot/cold/driving/parked all the same.

There are no consistent noises that rise and fall with rpms, just this initial ding. It sounds close to the radiator, mechanic was thinking water pump.

Around 100k kilometers and I use 93 octane gas in the USA. Fresh plugs,oil, and fuel filter. Any help would be greatly appreciated! I'm planning on doing the water pump and timing belt soon.

 

[gtrjohn.91]

Possible update: I can wiggle the A/C compressor tensioner pulley pretty easily. The belt doesn't seem loose, maybe the bearing is shot?

 

[Mike Rotchburns]

i recomend going under the hood and actuating the throttle by hand and listening for the noise.

as for the tentioner take the belt off and spin all the pullies listening for a grinding noise and check them for play.

 

[gtrjohn.91]

Another update: Replaced idler pulley and it wasn't the issue. Pulled the driver's side running light, the sound is definitely coming from one of the recirculation valves. Boost seems fine, I've never heard a recirc valve make a noise like this.

Maybe a bad spring? Didn't hear an air leak.

 

[Mike Rotchburns]

few things you can do to check for a leak is
1. smoke test it. this does require a smoke machine. they can be bought for as low as $90 on amazon and only go up for more sophisticated designs. or one can be made for about half that price.
you will see very clearly if you have a leak with this.
2. is to use a boost leak tester and spray soapy water on all the in cold side parts. intercooler, pipinng intatke, manifold ect. look for bubbles.

we have found that the stock recirc valves dont hold when you turn up the boost and start to leak. Also most are old now and start to fail.