Help identifying metallic "clunking" noise

[Joel M]

Hey guys, I'm having trouble identifying a noise coming from the engine bay while driving. The best way I can describe it is that it sounds like a piece of sheet metal being struck. I've uploaded a video of the sound here (sorry, it's difficult to hear over the exhaust): https://youtu.be/fu2CxOAeQo4

I thought it might be the power steering pump, but I just had that replaced and the noise persists. Does this sound familiar to anyone? It seems to happen most when accelerating or at higher RPMs, but sometimes happens when just cruising.

Car details: S13 with freshly rebuilt SR20.

Thanks in advance for any help you guys can offer.

[Kingtal0n]

holy shit it does sound like sheet metal bending. Ive never heard that before. Is there sheet metal under the car in the path of the air where it can bend? Maybe someone made a metal duct or something? get under there and look?

You can try a few normal diagnostics. See if you can get the motor to make the noise at idle. See if there is anyway to cause the noise while the car is sitting still. You could alternatively use a dynometer and run the car hard to see if its coming from the engine. If you can get the noise at idle/sitting still, then you can take off the belts and eliminate the accessories. And you can start pulling coilpacks.

freshly built engines scare me until they have 50k or so, but I've never heard an SR make that kinda noise.
Watching the boost gauge in the video makes me think it could be something on the exhaust side/turbo.

[Joel M]

Hey thanks for the response. I'll take a look under the car but it really sounds like it's coming from the bay rather than underneath.

I have had other intermittent turbo issues - about 1 out of 20 times I hit boost I'll hear a loud vacuum-like whine and lose boost for a while, then it comes back in a minute and is back to normal. No idea what that is or if it's related.

Thanks for all the advice. I'll try going through the rpms while stationary and see if I can recreate it.

[KAT-PWR]

holy shit it does sound like sheet metal bending. Ive never heard that before. Is there sheet metal under the car in the path of the air where it can bend? Maybe someone made a metal duct or something? get under there and look?

You can try a few normal diagnostics. See if you can get the motor to make the noise at idle. See if there is anyway to cause the noise while the car is sitting still. You could alternatively use a dynometer and run the car hard to see if its coming from the engine. If you can get the noise at idle/sitting still, then you can take off the belts and eliminate the accessories. And you can start pulling coilpacks.

freshly built engines scare me until they have 50k or so, but I've never heard an SR make that kinda noise.
Watching the boost gauge in the video makes me think it could be something on the exhaust side/turbo.

I'm going to have to second my good friend TaloniousMayhem here.

What are you running for an intake? Is it collapsing? I once had just a 4" to 3" 90* coupler off my turbo and it would suck the opening closed and cause a crazy noise and prevent boosting.

[Kingtal0n]

I'm going to have to second my good friend TaloniousMayhem here.

Im reaaallly sorry bro to tell you this, I hate to break the terrible news to you, to be the one to do it is just awful but... KA engines suck. :D


it really sounds like it's coming from the bay rather than underneath.

I have had other intermittent turbo issues - about 1 out of 20 times I hit boost I'll hear a loud vacuum-like whine and lose boost for a while, then it comes back in a minute and is back to normal. No idea what that is or if it's related.



there shouldnt be any turbo related noise or problem. that just makes me even more suspicious. THAT sounds like a bypass valve issue, but if you have a maf sensor the engine should die when you "lose boost" (Do you have a maf or map?). Also, if you bought a chinese turbo or similar bypass this could be your entire issue..

pics of the engine bay at this point would help. And a full build list of all parts. and how they are assembled (who did what, the same guy that did the engine bolted on the turbo? How handy are you?)

[KAT-PWR]

Im reaaallly sorry bro to tell you this, I hate to break the terrible news to you, to be the one to do it is just awful but... KA engines suck. :D
Well perhaps one day I can change your mind. :)

[Kingtal0n]

Well perhaps one day I can change your mind. :)

If you can hit 50k with a forged piston in a KA making 500RWHP that would impress me, but you need to prove the mileage.

I dont think its ever been done. Ever.

[Joel M]

there shouldnt be any turbo related noise or problem. that just makes me even more suspicious. THAT sounds like a bypass valve issue, but if you have a maf sensor the engine should die when you "lose boost" (Do you have a maf or map?). Also, if you bought a chinese turbo or similar bypass this could be your entire issue..

pics of the engine bay at this point would help. And a full build list of all parts. and how they are assembled (who did what, the same guy that did the engine bolted on the turbo? How handy are you?)

Not sure about the sensors, I'm not very handy myself. I had a couple of friends who are very experienced with 240s handle most of the build.

The engine doesn't die when I loose boost; I just can't build positive pressure momentarily after that vacuum noise, but eventually everything returns to normal.

The engine was remachined at a shop, but dropped in by different guys than those who finished the project and installed the turbo. It's a disco potato that came off another 240 where it worked flawlessly.

Ill get pics and more info when I get home from work. Thanks for all the input!

[Joel M]

Here's the only pic of the bay I have on hand: http://i.imgur.com/rp3yLJ5.jpg

[jedi03]

Put back end on Jacks is cheaper than dyno and let it run in gear...won't get the load but can see a lot more...