clacking sound when accelerating, w/video

[Stooklum]

I hope this question hasn't been answered here before, but we'll see.

I just bought a 5-spd '90 TSI AWD, and it has a problem with a clacking noise when accelerating. It only happens when the engine is cold, and gets less noticeable and eventually fades completely after about 5-10 minutes when the engine has warmed up. I've only noticed it under boost -- if I accelerate lightly without engaging boost I can't hear the noise at all.

I made a short video outlining what I'm talking about, you'll notice the clacking noise about midway through the video when I'm lightly boosting. Under hard acceleration, the noise will get a little louder, but the car still seems to build boost normally. Any ideas? The car is all stock.

Link to video:

http://oregonstate.edu/~reutimas/clack.htm (4.7 MB)

 

[Defiant]

Well, your file wouldn't make it through the cable in the amount of time I'd allow for it, but nonetheless, check your harmonic balancer.

 

[Stooklum]

Well, your file wouldn't make it through the cable in the amount of time I'd allow for it, but nonetheless, check your harmonic balancer.

Yeah, sorry about the file size, here is a much smaller wav file:

http://oregonstate.edu/~reutimas/clack.wav (181 kb)

This was recorded with the hood open, near the timing belt. The noise definitely sounds like it's coming from the timing belt area, so the harmonic balancer is a good guess. Why would it go away completely when the car warms up though?

 

[Stooklum]

Well, I just had the timing belt on the car done, so while I was at it I had the crank pulley/harmonic balancer checked out, and it was in good shape with no separation. The clanking noise remains a mystery, any other ideas?

 

[realhp=turbo]

Ive listened to your first video for like 10 min. I think that your noise is either shitty gas and some kinda funky lifter tick. My dad says that he would check the powersteering pulley first. Try taking the air intake off of the turbo from the vacume side and spin the impeller with your fingers, do you feel any chunkyness? Any play? To me I would still have to say its in the head. You might need your cam bearing races line honed or new followers. good idea with the flik dude.
mike

 

[Psycron]

Yeah, sorry about the file size, here is a much smaller wav file:

http://oregonstate.edu/~reutimas/clack.wav (181 kb)

This was recorded with the hood open, near the timing belt. The noise definitely sounds like it's coming from the timing belt area, so the harmonic balancer is a good guess. Why would it go away completely when the car warms up though?

I'm having the same sound after doing a timing belt job- no one seems to have an answer. I'm thinking the cause might be an over-tightened balance belt. The harmonic balancer (crank pulley) is also suspect but it was fine and didn't show any signs of wear or separation. Any help would be appreciated, I don't want this little sound turn into something bigger then end up rebuilding the top half of my motor again

 

[GSX20]

Please don't leave a thread hanging like this!
Did you ever figure out what the problem was, because i have the exact same noise coming from the belt area as you do/did?? If i rev it up in neutral it makes the clacking sound according to the speed of the engine. Same thing if i'm driving! It does seem to go away when the car is fully warmed up after driving it awhile. It's really annoying and embarrasing and i don't want to break down and bring it in to Satan if it turns out it's something really simple! Any feedback would be appreciated. Thanks

 

[Stooklum]

I haven't had much time to dink with the car lately, and the problem hasn't gotten any better or worse since. Over thanksgiving I'm going to check for boost leaks ( http://www.vfaq.com/mods/ICtester.html ) and exhaust leaks (with an air compressor hooked into one of the spark plug holes), right now I'm guessing it's a gasket problem somewhere, since the clicking sound completely goes away when the car warms up.

 

[yoshimitsuspeed]

It's funny your first post was on 09/12 and your last post was at 9:12 it messed with me a little.
If you want to bring it up to portland I would look it over for you.

 

[hellotbone]

Im having that exact same sound in my 6bolt in my 2G right now. Its not in the bottom end because I just pulled my pan tonight and checked all the rod bearings etc. I think its either piston slap or lifter tick.

 

[2.4 turbo Hyped]

There is so much crap spinning and whirring in these engines that its a pain to locate the sounds. Do you have a mechanics stethoscope? Can you create the sound whilst the vehicle is sitting still? If so that would be the method I would take.

 

[Psycron]

I get the exact sound Stooklum is getting, yet like he says there are no symptoms- car runs normally...but the sound wasn't there before I swapped heads. My pulley also appears to be fine, I inspected it when I removed it during the swap. I think this winter it'll be time to take the pulley side apart and inspect everything again. I will let you all know when I can rid myself of this sound.

 

[nuggets]

Phantom knock?


I get this same noise too around the SAME rpm but it showed up when i was driving normally 1 day and the car was warm. This was only like 2 days ago and i drove it 3 blocks with that noise, havnt touched it since. Ive been told it's rod knock and that i'll probably have to rebuild block . i should make a video of my noise as well.

 

[blackGSX2g]

Mine made a kind of grinding/whirring noise when it was first started up. I thought it was my turbo blades hitting the housing (old t-25) but when I replaced the turbo, the noise was still there. Didn't do anything to hurt performance, just a weird noise. I'm almost done swapping in a brand new 6-bolt...replaced everything but the ac compressor and PS pump. If it still makes that noise when I first start it up, I'll know its one of the pumps.

 

[Stooklum]

UPDATE: I found the problem. Turns out 3 of the bolts connecting the exhaust manifold to the head were broken, and the manifold was also cracked in several places. I had the holes re-drilled and then replaced the manifold, and now there is no trace of the clack.

 

[BigDaddy186]

Is this the phantom knock that I hear about. Just curious because my motor makes all kinds of funny noises ...and i dont have speakers on my computer so the link doesnt help me much.Im trying to quiet things up a bit but with very little luck. Maybe ill see if the bolt are the issue for me. I dont think so though....I got the ss header a couple months ago because that dammed stocker cracked and killer the turbo and the bolt seemed fine then. Ill check anyway. Thanks for posting that.

 

[Nerfherder]

Mine made a kind of grinding/whirring noise when it was first started up. I thought it was my turbo blades hitting the housing (old t-25) but when I replaced the turbo, the noise was still there. Didn't do anything to hurt performance, just a weird noise. I'm almost done swapping in a brand new 6-bolt...replaced everything but the ac compressor and PS pump. If it still makes that noise when I first start it up, I'll know its one of the pumps.

I have that exact same issue. Let me know if it goes away with your new setup.

 

[jab-619]

UPDATE: I found the problem. Turns out 3 of the bolts connecting the exhaust manifold to the head were broken, and the manifold was also cracked in several places. I had the holes re-drilled and then replaced the manifold, and now there is no trace of the clack.

I was going to say something. But you got to it befor me. When I got my car it was doing the same thing. The 1st thing I looked at was the manifold. The gasket was gone no one side. So I got a good deal no the car. Put a new gasket in and the sound is gone.

 

[Psycron]

UPDATE: I found the problem. Turns out 3 of the bolts connecting the exhaust manifold to the head were broken, and the manifold was also cracked in several places. I had the holes re-drilled and then replaced the manifold, and now there is no trace of the clack.

Great to hear it man! I'll be sure to check my mani after I port the exhaust inlet on the turbo. I dunno yet if there's broken bolts or if the gasket might be gone- I think I reused the old gasket so that could be the problem. Glad your problem is fixed

 

[Catbox_95]

EXACT same thing happened to mine, right down to the 3 broken exhaust studs. Glad to hear you've got it figured out!