Knock please help

Austin86250

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Alright 86 6.9 n/a has a persistent knock
New motor craft glow plugs
New injectors from Russ 9k miles ago
Only had enough battery juice to compression test a few so here as follows for what I have so far
1-420
2-450
3-380
4-450
5-470
6-440
7-460
8-400
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Poking around with my mechanics stethoscope and it’s definitely strongest at #3 injector hard line i dont here much knock anywhere else in this video I put the mic up to the stethoscope while it’s on #3 hard line

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Here’s the driver side under the valve cover

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Here’s the exhaust
No different in knock with intake on or off
Please chime in on possible causes/ places to investigate
 
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KansasIDI

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So my truck was making a noise like this. Then my brakes quit boosting. Turns out my vacuum pump started to fall apart. I think it may have been weak, as @IDIBRONCO had said earlier. The brakes still aren’t quite right, I think it needs a master cylinder.

I don’t think that’s a lifter, I have heard a bad lifter on an 83 6.9, which if I recall correctly are slightly different. But it made a very noticeable popping noise, sort of like a 2 cylinder John Deere.

You could have a number of things that are capable of making that sound. In the engine itself, I am guessing pushrod? Did you look over those rocker arms? Sounds like your on a track with the number 3 cylinder. Maybe pull some rockers and check pushrods.

Is your oil psi good?

Sorry I am not of much help, I don’t know what noise means what on these engines.
 

Austin86250

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So my truck was making a noise like this. Then my brakes quit boosting. Turns out my vacuum pump started to fall apart. I think it may have been weak, as @IDIBRONCO had said earlier. The brakes still aren’t quite right, I think it needs a master cylinder.

I don’t think that’s a lifter, I have heard a bad lifter on an 83 6.9, which if I recall correctly are slightly different. But it made a very noticeable popping noise, sort of like a 2 cylinder John Deere.

You could have a number of things that are capable of making that sound. In the engine itself, I am guessing pushrod? Did you look over those rocker arms? Sounds like your on a track with the number 3 cylinder. Maybe pull some rockers and check pushrods.

Is your oil psi good?

Sorry I am not of much help, I don’t know what noise means what on these engines.
I too have heard a collapsed lifter it was a misfire tick and noticeable thud with intake off
I don’t have exact oil psi numbers but with valve cover off she gets to spraying
 

Austin86250

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Don’t really know what I’m looking for but there’s virtually no wear pushrods not bent
How do you reinstall the rockers?
 

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IDIBRONCO

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How do you reinstall the rockers?
Put them back on and torque the bolts down. Be aware that your style of rocker uses the aluminum pivots that are known to break. There is no replacements made. You just have to upgrade to the 7.3 style rockers.
 

Austin86250

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i forgot to add that this is intermittent. some days its mild somedays hard somedays not there, it seems after running it for a long time especially after pulling a load it goes away.
dug up one of my old threads on this knock bart told me about using a vacuum hose as a stethoscope.

would a exhaust knock just be the manifold/ mating surface? or can an exhaust leak at the manifold to y connection be of issue? i got a homemade collector set up going on but this knock has been around all the way since i got it with factory exhaust
 

Austin86250

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Well Injector bore of the problem cylinder the washer was definitely not sealing
Swapped Injector 1 and 2 and it moved to 2 so it really was the injectors this whole time
 

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Nero

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I like easy diagnosing. Time for a set of shooty squirters in that bad boy
 

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