diagnosing cylinder knock - Ford Powerstroke Diesel Forum
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post #1 of 3 Old 10-24-2011, 04:28 AM Thread Starter
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diagnosing cylinder knock

On my wifes 99 I have knock. Let me start by saying I believe the injectors are tired. At first diagnosing, I needed 2 injectors, cylinder 7 and 3. They were real loud an and making a ton of racket(real bad when cold) I have ticking coming from some others but I am chasing a knock. I am thinking piston or wrist pin. AT 50 mph when I take my foot off the accelerator all goes quiet like it should, but if you listen carefully the knock is there, just a lot quieter due to no fuel explosion in the cylinder. I believe its cylinder 3.
(new reman injector in the hole) (casserly)
When i unplug that cylinder its odvious that thats the loudest source my noise.
I find that if I unplug a cylinder and walk into my house, or walk away from the truck, that the noise I am trying to fix is easier to hear. Getting away from the other injectors makes hearng the knock clearer.
It does not seem to get much louder when driving it. I think I have a piston that is failing.
My truck had injctor noises a while back, but made no noise at 50 mph when i took my foot off the pedal an let it coast, this one does have a quiet
knock still.
any thoughts?

2008 6.4 f250 lariat 4wd
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post #2 of 3 Old 10-24-2011, 08:35 PM
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these trucks dont often "knock", besides injectors causing issues, i'd say change injectors and go from there, i bet thats your problem in the first place to be honest.. obviously get a compression test if you want.
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post #3 of 3 Old 07-11-2012, 06:07 AM
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did you ever find out what the knock was? i have an early 99, that was knocking, took it to a shop and asked what was wrong, 95 dollars later the told me i had a bad injector, they wanted 1500 to replace bank of 4.

took truck home, replaced all 8 injectors, still knocking. determined that #7 cyl is where noise comes from, i believe it's the wrist pin after listening with a stethescope.

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