Spun Bearing?

greyford1979

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So my truck has developed a knocking noise :cursing:. The weird thing is that it's intermittent. No knocking when under acceleration, only when idling. I was going to get a video after working today, but of course no knocking noise. Even when it does, it sometimes just goes away. Pisses me because the truck isn't abused and well maintained. I'll try to get a video of it tomorrow if it decides to do it. And yes oil is good, not low and 1,300 miles away from needing an oil change.
 

co04cobra

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I would guess it’s a intermittent fuel knock. Most of the time lower end noises won’t come and go.
 

greyford1979

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I would guess it’s a intermittent fuel knock. Most of the time lower end noises won’t come and go.

Yeah that's why I thought it was weird. The knock does have a slight squeak to it, hopefully I can get a video of it. Or maybe it will just never do it again as long as I try to get a vid lol.

An accy or idler issue? Might try idling it with the belt removed.

It's definitely coming from the engine, not from any accessories. Actually seems to be more noticeable in the cab with the windows up than outside. These damn 7.3s with single shots are definitely not quiet lol.
 

lincolnlocker

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I haven't listened to the video yet as I'm at supper but what you described is flexplate/converter noise.

live life full throttle
 

powerstroked08

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If you just rev it up is it still there?. And if you were to load it(put it in drive and hold the brake while giving it throttle) does it go away?

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greyford1979

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If you just rev it up is it still there?. And if you were to load it(put it in drive and hold the brake while giving it throttle) does it go away?

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Really hard to tell, don't really notice it under those situations. Mostly just hear turbo and injectors.
 

greyford1979

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Still not ruling anything out though. But with the low compression, and now this. Why couldn't this at least wait till it's warmer out so that I can diagnose this lol. I have confirmed though, not the flexplate. It is getting louder, and not really noticeable on start up. When the engine is warmed up, it's much louder. Truck has constant good fuel pressure with the Irate system, needle doesn't move. Haven't noticed much in the way of losing any power. Once fully warmed up, it does idle rough occasionally with blue smoke like when sitting at a stop light. Sometimes it will be just fine sitting at a light, and then it's like it misfires and blue smoke starts pouring out even though there wasn't even prior to the misfire. Also it did start a little harder this afternoon. Haven't pulled the filter and cut it open to check that yet.
 
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EPA

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Sounds like injector/fuel knock... It actually sounds just like mine did awhile back.. I had low fuel pressure fixed that and after that an injector must have messed up. A buddy of mine had an injector that didn't seat well cause a similar knock... Mine was driving me crazy... Sometimes nothing then bam loud knock sitting in traffic haha.. Get home nothing haha... Finally pulled injectors found them almost completely clogged... Issue went away after new injectors. I pin pointed it with a huge screw driver to my ear... Traced the noise to the heads... Not lower end. Mine was loud in cab and in drivers wheel well.
 
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greyford1979

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Sounds like injector/fuel knock... It actually sounds just like mine did awhile back.. I had low fuel pressure fixed that and after that an injector must have messed up. A buddy of mine had an injector that didn't seat well cause a similar knock... Mine was driving me crazy... Sometimes nothing then bam loud knock sitting in traffic haha.. Get home nothing haha... Finally pulled injectors found them almost completely clogged... Issue went away after new injectors. I pin pointed it with a huge screw driver to my ear... Traced the noise to the heads... Not lower end. Mine was loud in cab and in drivers wheel well.

That's exactly how mine sounds, loud in cab and in driver's wheel well. I have been suspecting a bad injector for some time now even before the knock. In another thread I had I mentioned something about that months ago after having some fuel pressure issues. When I'm coasting down a hill sometimes is when it seems like the issue is not even there at all. These injectors aren't even 5 years old and have less than 50,000 miles on them.
 
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EPA

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I would pull drivers side and inspect... You could disconnect them 1 by 1 and see when the noise goes away... Take that injector and swap it with another see if the noise follows it.
I'm starting to think of 7.3s like this... If you think you have engine failure... You probably dont...
But if you think you have injector issues.. You probably do haha.
I lost sleep thinking I would need to swap out an engine in the winter without a proper work space... Thank God it was an injector issue.
 

greyford1979

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I would pull drivers side and inspect... You could disconnect them 1 by 1 and see when the noise goes away... Take that injector and swap it with another see if the noise follows it.
I'm starting to think of 7.3s like this... If you think you have engine failure... You probably dont...
But if you think you have injector issues.. You probably do haha.
I lost sleep thinking I would need to swap out an engine in the winter without a proper work space... Thank God it was an injector issue.

I did that with the injectors back in I believe at the end of August or beginning of September when I did a compression test and installed my Irate fuel system and didn't really notice any difference. Before that was when I first suspected injector issues. However I did that with my old injectors that were bad with over 250,000 miles on them and didn't notice a difference with them either even though they did end up having multiple bad injectors.
 

greyford1979

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Also for got to mention. I have multiple tuners on my Hydra, and it seems like the knock is slightly quieter or louder depending on which tuner I'm running.
 

co04cobra

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That would lead me to think a injector still and it's changing with PW in the tune. JMO.
 

EPA

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I 2nd that... My hot tune would aggravate the issue.
Still did it in stock tune but after a few minutes of driving in hot tune the noise was loud and very defined. Its funny because after hearing the video I remembered exactly why I changed the injectors haha, my wife even listened to the video and thought it was a recording of my truck haha... And as said mine started up a few weeks after my low fuel pressure issue.
 

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