Paducah Home Theater Posted May 10, 2016 Author Share Posted May 10, 2016 Do phone microphones block certain frequencies or something? Strange that I can't record it at all. Was wondering if my calibrated USB microphone and my laptop would capture it better. Quote Link to comment Share on other sites More sharing options...
USNRET Posted May 10, 2016 Share Posted May 10, 2016 I have isolated, amplified and repeated eleven times, a two second section which I believe has the sound you are hearing. https://drive.google.com/open?id=0B_-5nvuxy-j7T21xSHhhUVBtV28 Sounds like valve clatter... One of three things about that recording 1) very very low RPM 2) recording slowed way down 3) I don't remember what valve clatter sounds like and I have heard it a LOT but recall the frequency or would it be tempo to be much greater Quote Link to comment Share on other sites More sharing options...
jason str Posted May 10, 2016 Share Posted May 10, 2016 I can't tell anything from the noise in the video but must say those spark plugs are a very poor design for something installed in an aluminum head. Quote Link to comment Share on other sites More sharing options...
JJkizak Posted May 11, 2016 Share Posted May 11, 2016 I ran it through my Vegas Pro software and noise gate and it sound like a mechanical problem and it was very steady, kind of like the drummer from Led Zeppelin. JJK Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 11, 2016 Author Share Posted May 11, 2016 (edited) I used Windows Voice Recorder on my laptop with my calibrated UMIK microphone and finally captured it. Let me know what you think. It is very loud and piercing, sounds like something is about to blow up. http://www.metropolislakeoutfitters.com/rattle.m4a Edited May 11, 2016 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
mustang guy Posted May 11, 2016 Share Posted May 11, 2016 (edited) Man that sounds like the cat converter to me. Little pieces of ceramic getting blown around but can't get past the honeycomb. What does everyone else think? Edited May 11, 2016 by mustang guy Quote Link to comment Share on other sites More sharing options...
Wolfbane Posted May 11, 2016 Share Posted May 11, 2016 Man that sounds like the cat converter to me. Little pieces of ceramic getting blown around but can't get past the honeycomb. What does everyone else think? Hard to tell but does not sound like pre-ignition or detonation to me. 1 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 11, 2016 Share Posted May 11, 2016 Haha. I was going to say that it could be pre ignition. It's random enough. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted May 11, 2016 Share Posted May 11, 2016 (edited) It sounds metallic like a loose heat shield or ceramic in a cat. I bet if any of us sat in the truck when it was making that noise we would know exactly what it is. I wonder if it is a squeak on the heat shield where the hole is elongated. It would also rattle. You wouldn't know it was loose unless the conditions were right. Edited May 11, 2016 by mustang guy Quote Link to comment Share on other sites More sharing options...
USNRET Posted May 11, 2016 Share Posted May 11, 2016 Don't "sense" it. I would have to drive and lug the engine at mid rpm under a load. I would shift up too early to cause the issue then steadily increase pressure on the throttle maintaining the load until a point that rpm / torque matches and overcomes the load. I'm out; from what I hear it's not pinging, piston knock, valve rattle. Go sleep in a Holiday Inn Express and try again.These are my thoughts and not intended for troubleshooting purposes.On the other issue: that is a lot o'bucks to spend in an attempt. Being a die hard GM guy, I have to agree with a previous post, buy a Chevy Quote Link to comment Share on other sites More sharing options...
mustang guy Posted May 11, 2016 Share Posted May 11, 2016 Have your mechanic ride on a creeper under the truck while you drive down the road. That's a sure fire way to find the noise. 2 Quote Link to comment Share on other sites More sharing options...
Ceptorman Posted May 11, 2016 Share Posted May 11, 2016 Have your mechanic ride on a creeper under the truck while you drive down the road. That's a sure fire way to find the noise. Mark (MKP) to the phone Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 11, 2016 Author Share Posted May 11, 2016 The odd part about the idea that it's the converter is that it's mostly just on or off, there's not infinitely varying degrees of loudness. If it starts rattling, I can let my foot off the gas the tiniest bit and it will stop. Quote Link to comment Share on other sites More sharing options...
Ceptorman Posted May 11, 2016 Share Posted May 11, 2016 Have you crawled under your trucked and inspected it? Heat shield, exhaust system mounts? Quote Link to comment Share on other sites More sharing options...
USNRET Posted May 11, 2016 Share Posted May 11, 2016 (edited) Converging / diverging ducts One of the basic jet engine theories which applies to the gas flow thru the cat. Varying any one changes the other; more throttle equals more pressure and volume. If you have a 'loose' internal cat part, this MAY explain it as it could set up exhaust gas flutter within the cat thereby causing internal 'rattling' that is not influenced by external excitation (hammer).In a jet engine, at its worse, it causes the gas pressure at the diffuser entry to be greater than compressor exit pressure and creates back pressure which leads to compressor stall (fire out the intake) Yea, this is not a jet engine but the gas (exhaust) flow principles are the same even with a balloon; I am talking about the disturbance of gas flow creating vibration to loose parts. So IF you have a blockage (tested good) or a loose internal part in the cat than increasing flow and pressure at the cat entry could lead to flow disturbance thru the cat (vibration = noise) until the velocity of the gases exiting the cat equals the entry velocity and the flow smooths out.Now I'm talking some BS! edit: and I lied I wasn't out...then Edited May 11, 2016 by USNRET Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 11, 2016 Author Share Posted May 11, 2016 Have you crawled under your trucked and inspected it? Heat shield, exhaust system mounts? Three guys at the muffler shop did, twice. Only thing they found was that there is a floppy heat shield on a converter but it does not make the high pitched metallic sound. They whacked on the converters and muffler and didn't find anything obvious. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 11, 2016 Author Share Posted May 11, 2016 (edited) They figured it out already, within 30 seconds of test driving it. When it is put into 4wd high, the issue goes away. Not sure why this was never thought of before, either by me or the three other shops. I guess I thought that since the front axle wasn't under power then it didn't matter. Anyway, they think it's the vacuum line actuator on the passenger side like somewhere around the hub, one of the parts that pertains to it. Said they had the exact same problem two weeks ago and it took them three hours to diagnose it and this sounded the exact same way. Waiting on them to figure out exactly what part it is and give me a price. Edited May 11, 2016 by MetropolisLakeOutfitters 2 Quote Link to comment Share on other sites More sharing options...
USNRET Posted May 11, 2016 Share Posted May 11, 2016 Good deal! 1 Quote Link to comment Share on other sites More sharing options...
Ceptorman Posted May 11, 2016 Share Posted May 11, 2016 Awesome news…..at least you know what it is, and it probably won't cost too much to fix. 1 Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 11, 2016 Author Share Posted May 11, 2016 I have to agree with a previous post, buy a Chevy All I've got to say is that it's pretty bad when a Chevy owner has to go to the Ford dealership and pay $129 an hour to get it fixed. Pic from this morning. 2 Quote Link to comment Share on other sites More sharing options...
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