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cory, GMC Technician
Category: GM
Satisfied Customers: 160
Experience:  14 years of gm experience ase master tech with advance engine performance
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2002 GMC: 000 miles..vibration..clutch in or trans in neutral (..rev

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I have a 2002 GMC 2500 HD crew cab with a Duramax diesel and a 6 speed manual transmission and around 100,000 miles. It recently started exhibiting a vibration that starts around 1600 RPM, peaks around 1750, and goes away over 1900 RPM. It originally felt like it was a wheel balance issue, but it is now clear that it's coming from the engine, as it's present in every gear, and can also be felt with the clutch in or trans in neutral (with engine rev'd to 1750 RPM).
My local dealer thought it was a bad injector or 2, as he tested them and found some bad ones. So, I had them replace all 8 injectors, but the vibration is the same as before.
Could it be the flywheel? I understand the dual mass type flywheel on these trucks can be problematic? Thanks for the advice
Hi there my name isXXXXX have seen a bunch of these. Heres how I check these. First I like to see if this is coming from the engine itself this vibration should be present with vehicle stationary reved to the rpms you mentioned If the vibration is still present I like to eliminate simple things like bent pulleys and belt issues by removing it to see if it goes away. If it is still there I like to see the injector balances with the scan tool, but with new injectors i doubt there is a problem there. I also like to see a compression test done all should be around 450 psi and all the cylinders should be within 70% of each other if they are this is not the cause of the vibration (tip: typically compression variances will show up at idle as well and usually have more smoke than usual). If you find nothing else in these checks i like to fish a magnet in to the bell housing near where the slave hose goes in, because when the dual mas flywheel starts to fail it will typically generate metal debris. If you get metal on you magnet the dual mass flywheel is coming apart. I hope this helps you I know how frustrating this vibration issue is and have delt with a bunch of them. If this answers your question go ahead and click accept, or if you have more questions feel free to ask. Thank you. Cory
Customer: replied 6 years ago.
Yes, it's there when the vehicle is sitting at idle and engine rev'd to 1750. It also shakes/vibrates a lot at idle. Is there a hole of some sort to fish a magnet into on the bell housing, or ?
Would you recommend replacing the flywheel with another stock type dual mass unit, or with an aftermarket single mass type?


Yes there is holes to fish a magnet in where the hydraulic hose goes into the bell housing. I just replaced one of these last week and I replaced it with a aftermarket 1 piece flywheel, and was really impressed at how well it worked. I can't remember the brand, but it came from an on line performance parts warehouse. So I recommend trying the one piece just for reliability. I had just done this cluch 2 years ago and fell apart again so the customer brought me a one piece conversion. It bolts in the same as the 2 piece so no modification is needed. I hope this helps if so click accept, or if you need more help feel free to ask. Thanks. Cory


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