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Discussion Starter #1
2002
LB7
3500
2WD
UTILITY BED
250k Miles
ALL STOCK

Check the links for some of my attempts to capture the "knocking / clacking sound".

Motor dose not smoke at all and balance rates are within spec.

No knock at idol. Apon acceleration the sound starts and increases in speed and loudness as you accelerate. Its quite loud just buzzen around town.

Now, under certain conditions it goes away, like you hit an off switch. This happens under 1/2 - 3/4 throttle say merging onto a freeway. As long as you stay into it, once you hit about 2600 RPM, It stops and will shift without knocking.

Once you let off, it comes back instantly as the RPMs drop, and when you start to accelerate. If you accelerate normally onto the freeway it will knock constantly. Only under the heavier acceleration can you get it to stop.

Sound and vid quality is sub-par I know..

I welcome all thought and thank you for you time. I have some ideas of what it might be and have read a lot about different knocks. None of them seem to fit the bill. Tried to include what I could think of that would be of help.



Normal driving :


Hear the knock up to about 2600 RPM :


Knock stops at about 2600 RPM with shift :

 

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Sounds similar to the 01 I'm working on. I ended up replacing 2 injectors that were just barely out of spec & that fixed my knock. I'm guessing yours is fuel-related as well, as it's not consistent through the rpm range, and also not completely random. I'd search around & do as much diagnostics on the fuel system as you can.
 

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Try the FUEL PRESSURE RELIEF VALVE/PLUG. $30 part, 30 minute job, amazing results. From what I have found, the darn thing is designed to allow too much fuel to bleed off the system after a couple of heavy accelerations, and never regains it's full pressure.
Look it up on you tube. It fixed my problems after trying everything else.
 
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