Need Help Identifying Sound in Motor

[DSM_23]

Hey, ok Ive been trying to figure out this sound on my car for about 3 1/2 years, alot of times I've blown it off but sometimes it really bothers me that I dont really know what it is. It sounds very close to the car in the clip in the link. I figured that if it was a rod it would be getting worse over time or would have blown by now since its been nearly 4 years since it started this noise. I used to think it was a balance shaft bearing, but they were taken out. Im completely stumped on what it is, I was thinking it was a timing belt tensioner but everything was changed out down there while the motor was out. Any ideas people so I can solve this mystery???

justin

Link to clip with car with similar sound..

http://video.yahoo.com/video/play?p...od+knock&toggle=1&cop=&ei=UTF-8&vback=Results

 

[LunarEclips]

did you do a compression test? what did you get? start from there....4 years is a LONG time to deal with that annoying noise.

 

[DSM_23]

yes i have done a compression test. 160 across, and you dont hear it much while driving, unless you raise the rpms say.. 3k let off throttle and then lightly apply it again then you can hear it easily. But as soon as you lay into the throttle it dissapears.

 

[T2Small]

My old 4G63 made a little bit of that noise. When I tore down the 4G63 the rods and bearings looked fine.

I really wouldn't worry about it right now unless it gets worse. The only motor that I have seen die of "rod knock" sounded a LOT worse under power. It spent a day on track, and by the afternoon session had a VERY LOUD knock/clatter sound under power. It finally ejected bits of rod and bearing for about 100 feet down the track after punching free of the block.

 

[DSM_23]

well Im not expecting the motor to just blow up soon, since its done it for so long, it just bothers me sometimes and I get all paranoid, and now I really want to find the cause. I took it up to a shop and had them listen to it and they said it sounded like a piston skirt......they arent the smartest people so I questioned their thinking , but I really wish someone could give me some clues as to what the hell this sound is...its driving me crazy.

 

[Nanan]

If that were a 350 block I would say it was piston slap for sure cause it sounds just like the engine I used to build a 383 for my S-10.

Was the engine ever re-build? Did it get boared out or new pistons? If the engine was boared and the wrong size pistons were used then slap will happen till something blows. If forged pistons were put in they also tend to slap even if they are the correct size.

 

[DSM_23]

The motor was redone, except for the block, the block was checked by a reputable DSM shop, and everything checked great and didnt need a rebuild at all.

 

[DSM_23]

Come on someone has to have some idea what it is

 

[andymoraitis]

Just for kicks, check the T-belt tensioner or idler pulleys. Also check for a separating crank pulley. If it isn't any of those things, pull the valve cover and see if you can push any of the lifters down with your finger. If you can, it's a collapsed lifter. I have to agree that it doesn't sound like rod knock, but does mildly resemble piston slap (almost a diesel motor kind of sound)

Let us know what you find.

Andy

 

[DSM_23]

Hmm, ok well tmw I think I'll take off the timing belt cover and check everything out, the whole front case etc was replaced about 3500 miles ago so it should be alrite, however im skeptical about the tensioner/ pullys as well. The lifters arent the cause because it did it whenever I had the stock lifters and now with the 3g lifters. How would it be possible to have piston slap on the stock bore/pistons? Thanks for the reply

justin

 

[andymoraitis]

Justin,

Piston slap usually isn't a common occurence on the stock bore. I've heard of some 2.3 and 2.4 blocks doing it although I don't have the problem. Check the other stuff first. I'm wondering if it couldn't also be a sticky valve. Anyway, let us know what you find first on the crank pulley and tensioners and then we'll go from there.

Andy

 

[chrisfrye]

mmm music to my ears. I should get a recording of my car, its about 4x as worse, started out the same sound as you, around 3k+rpms, normally only hear it when im accelerating or decelerating. But its gotten worse on mine for sure, it sounds like i have a v10diesel truck riding down the road, a little rediculous. i'm planning for a jdm swap. I've been told by pleanty of mechanics its rod knock. i dropped my pan a little while ago and noticed a small amount of shavings. my motor was also rebuilt so i'm not sure if that was from before the rebuild or not, but i know they didnt seat my rear main seal properly and on my maiden ride home from philly(400miles) i lost enough oil to start the knock. Its gotten worse over the 25k miles i've had it. How many miles you put on your car in those 3 1/2 yrs?? If its not getting worse i wouldnt worry too much about it. you can always drop your oil pan and inspect the bearings.

 

[acbigshow]

could be lifter tap

 

[DSM_23]

mmm music to my ears. I should get a recording of my car, its about 4x as worse, started out the same sound as you, around 3k+rpms, normally only hear it when im accelerating or decelerating. But its gotten worse on mine for sure, it sounds like i have a v10diesel truck riding down the road, a little rediculous. i'm planning for a jdm swap. I've been told by pleanty of mechanics its rod knock. i dropped my pan a little while ago and noticed a small amount of shavings. my motor was also rebuilt so i'm not sure if that was from before the rebuild or not, but i know they didnt seat my rear main seal properly and on my maiden ride home from philly(400miles) i lost enough oil to start the knock. Its gotten worse over the 25k miles i've had it. How many miles you put on your car in those 3 1/2 yrs?? If its not getting worse i wouldnt worry too much about it. you can always drop your oil pan and inspect the bearings.

I've probably put about 20-25k on it in that time period. Ive only put about 3.5k on it since the motor was taken out though. The sound has not gotten worse thats the thing which is good but still annoying at times. While driving around you cant really even hear it I have to almost make the car make the sound for someone to hear it like hold rpms about 2.5-3.5k and let off the lightly apply throttle. Lifters are brand new 3g lifters so I highly doubt its that. Today me and a friend are going to check out the timing belt tensioner/pullys, and the crank pully and see if we can find something there, so I'll check back afterwords. Also could you send me a clip of your car making that sound if you have one?

justin

 

[chrisfrye]

okay i did the best i could, the only audio recorder i had available is my cheap 20$ mp3 player i got off ebay. go figure it has a micrphone on it. It really drowns out most of the quieter noise over the larger(if i get ahold of a half way decent mic or digi i'll update it, it really doesnt do the audio justice).

http://www.geocities.com/thechrisfrye/MIC__004.WAV

if you listen closly at the beggining of me revving it or starting it or after i stop revving, you'll hear the lifter tick, when they're starving. and i can hear multiple lifters ticking(keen ears). the knock starts around 2k rpms lightly and if i hold it around 2500 its at its worse(sucks thats good crusing and holding speed for most my driving)around 3-4k rpm it seems you can mainly only hear it more intermintently and speriodic, but about 4.5k+ if you listen close you can hear a real fast deep drum roll type sound(would be it again) haha. blah! you can also take a peice of vacuum cable you have lying around and cut it to appropiate length you can listen in one end and move the other end around the block to try to focus more on the sound.. good luck!

 

[andymoraitis]

That's rod knock in the sound clip. To verify it you can either:

A. Pull and reattach plug wires one at a time with the motor making the noise. If its stops when you pull any wire, it's a spun rod bearing.

B. Pull the oil pan, check for shavings and prepare your wallet for a rebuild on the bottom end.

Sorry,

Andy

 

[chrisfrye]

haha yeah .. Good idea on the spark plugs! i didnt even think of that, i'll check it out tomorrow. I figure i'm just going to go jdm from a local dealer for 1150 fulldress. can rebuild my old engine w/6bolt crank on spare time.

 

[chrisfrye]

Hey i was thinking before i went to bed. Now please correct me if i'm wrong as i've never rebuilt an engine, nor have a complete understanding of how engine works. How would the spark eliminate rod-knock? the rod (and chewen bearing) is still turning on the crankshaft regardless of the spark plug? now manybe it has something to do with the way the spark ignites the a/f mixture and puts more pressure on it?? i have no idea, but it seems if the rod bearing were bad and the rod was still turning it'd still make the sound... maybe i'm completely off, haha just a thought. i'm going to check it out on my lunch break.

 

[andymoraitis]

Chris,

When you pull a plug, the combustion cycle on that cylinder goes dead and the load is removed from the rotating assembly. While the piston and rod still move, it's not under the same cylinder pressure as it would be if the plug wire was in place and igniting the fuel mixture. In simple terms, you're removing the load and much of the associated stress on that particular cylinder.

Let me know if that helps out,

Andy

 

[chrisfrye]

Good, thanks! that was my best guess but i just wasnt sure if there still be enough pressure to put enough stress on the bearing.
but i wasnt able to get my wires off the spark plugs, i started tearing the boot pulling on it so hard, on all of them. peices of crap! they're either bosch or beck/arnley i picked up from autozone i dont remember. had the same peices of crap on my car when i first bought it and went to change my plugs, and bought new ones didnt even notice they were the same! anyways when i unplug the wires from the ignition pack it shoots the spark out to the fuel rail and intake mani, and thats bothers me haha. especially if i have to pull the throttle cable to hear the noise. is that alright for the exhaust/turbo/engine? revving it up without a cylinder firing. anyways i didn't have any rubber gloves on me and i'm going to order some magnacores tonight so i can be done with these.

Ohh and i found like a good two baseball sized amount of maybe lint, maybe sometype of grey fiberglass insulation? in between my intake mani loop and underneath the fuel rail.. haha it just seemed odd, or not?

 

[Julioluko]

Woah wait a sec yes it could be rod knock, but for that long of time without getting worse??? on two diffrent DSMs we had simmilar noises and it was acctaully a bad exaust mainfold gasket that was letting noise right from the engine out instead of all the way to the muffler. I didnt even see fumes comming from the leak, but two gaskets (warped head) made it dissapear. You might want to check it out.

 

[andymoraitis]

Woah wait a sec yes it could be rod knock, but for that long of time without getting worse??? on two diffrent DSMs we had simmilar noises and it was acctaully a bad exaust mainfold gasket that was letting noise right from the engine out instead of all the way to the muffler. I didnt even see fumes comming from the leak, but two gaskets (warped head) made it dissapear. You might want to check it out.

Not a bad idea at all. Good suggestion!

 

[DSM_23]

Yea I'll check that, me and my friend havent gotten to check everything out like we had planned yet, so whenever that gets accomplished I'll be sure to update. Keep the comments coming they've been very helpful.

justin

 

[Fabian972]

Woah wait a sec yes it could be rod knock, but for that long of time without getting worse??? on two diffrent DSMs we had simmilar noises and it was acctaully a bad exaust mainfold gasket that was letting noise right from the engine out instead of all the way to the muffler. I didnt even see fumes comming from the leak, but two gaskets (warped head) made it dissapear. You might want to check it out.

Mine makes the same sound at idle you don't hear it when you step on it you'll hear the clacking and this started 2 1/2 after i had my motor rebuilt (completely) this motor has 17k to 18k miles on it when the sound started i notice i am missing two bolts on my ehxaust manifold could that be the problem? The following day i changed my oil i saw no shaving just pure black oil.

 

[DSM_23]

Ok I finally have an update. We took off the timing belt cover, and belt and checked the pullys/ tensioner etc. Everything looked great. I was pretty upset because I wanted to find the problem to be something in there. We reved it just like in the video and the area the sound seems to be coming from appears to be around the lower part of the engine, around the crank pully/oil pump. We spun the oil pump and it spins freely and it appears fine. I am totally lost as to what it is. I dont see what it could be in the block that wouldnt have gotten worse over time or hasnt blown up yet? Any help would be great...

justin