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Discussion Starter · #1 ·
We regularly go up and down a steep mountain road. Our 2011 truck used to make no noise going downhill with the engine brake on, you could just feel it slowing the truck down. Now it makes a rumbling sound which appears to be coming from the top of the engine. If I turn the engine brake off no noise. I guess the turbo is the engine brake? Any ideas?
 

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Possibly a vanes stuck?

Do you have a monitor so you can see your vane position while driving and when Turbo Brake activates? If you do when it first activates vanes should go to 100% and then decrease til the truck downshifts then it goes back to 100% in the lower gear and repeats the process.
 

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Discussion Starter · #3 ·
Sorry for not getting back sooner. I have been real busy. It seems that it stays louder longer
the heaver the load. your info makes sense
 

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We regularly go up and down a steep mountain road. Our 2011 truck used to make no noise going downhill with the engine brake on, you could just feel it slowing the truck down. Now it makes a rumbling sound which appears to be coming from the top of the engine. If I turn the engine brake off no noise. I guess the turbo is the engine brake? Any ideas?
Turbo Brake. Turbo Vane actions use the engine compression to slow.
I would look for an exhaust leak, perhaps one of the bellows on one of the up pipes has cracked, or a problem with one of their gaskets leaking.
 
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