2008 Dodge Ram 3500 - Turbo screech

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Over the last couple of weeks, I have noticed a screeching noise every time I engage the exhaust brake function. This truck has a variable-geometry turbo that closes down the VG mechanism after a couple of seconds' trailing throttle. This assists decel of the truck when towing or heavily loaded. The problem started only occasionally during exhaust braking mode, but now the screech occurs every time, and is now even beginning to occur under hard acceleration when the turbo is putting out high boost. Has anybody else out there had this problem on the 6.7L Cummins? I am theorizing that the thrust bearing in the turbo may be going out, and would require an expensive repair. Are there other possible causes for the screeching noise?
 
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RI
Check for exhaust manifold leaks or cracks, or any other pre turbo exhaust leaks for that matter (including EGR piping). Also check the turbo for any excess bearing play.
 
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48
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KS
Not sure if it's the same or not but mine it was more like a "turbo bark" and it only happened under acceleration. Like cruising down the hwy and accel to pass type. It did it for over a year and a half. Nothing else seemed out of place, there wasn't a hesitation or stumble of any kind just the bark. It also did it in cruise and going uphill when you could feel the truck giving more fuel to climb. Turbo eventually went after cel and dealership replaced on my dime. Hope this helps and I hope this isn't the case for you.
 
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TX & ON
1/ Manifold gasket leaks; check for soot trails, and replace with MLS gaskets if needed. 2/ Check for lateral & back'n'forth play on your compressor wheel. 3/ Check for boost leaks - they can make banshee noises at times. 4" plumbing cap + Schrader valve + 20 psi regulated air, no more than a 3-5 psi drop on your boost gauge if your crank is at the correct position. 4/ Clean the turbo vanes; Mopar sells an outstanding soak/cleaner. 5/ Is your '08 deleted? 6/ No difference between 5.9 vs 6.7 as far as your issue ;-) 7/ Junk the Holset & go SXE + 4" downpipe, if your turbo is beyond salvage. Rebuild vs R&R, depending on your time/skillset.
 
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7,900
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Originally Posted by ofelas
1/ Manifold gasket leaks; check for soot trails, and replace with MLS gaskets if needed. 2/ Check for lateral & back'n'forth play on your compressor wheel. 3/ Check for boost leaks - they can make banshee noises at times. 4" plumbing cap + Schrader valve + 20 psi regulated air, no more than a 3-5 psi drop on your boost gauge if your crank is at the correct position. 4/ Clean the turbo vanes; Mopar sells an outstanding soak/cleaner. 5/ Is your '08 deleted? 6/ No difference between 5.9 vs 6.7 as far as your issue ;-) 7/ Junk the Holset & go SXE + 4" downpipe, if your turbo is beyond salvage. Rebuild vs R&R, depending on your time/skillset.
Thanks for all the suggestions. Answers to your questions: 5. No, it's not deleted. 7. What is an SXE? Is it a later-model turbo? Or aftermarket fixed-geometry? I never learned about the later trucks, other than to avoid emissions controlled diesels of any kind. But it became impossible to keep running my 19-year-old truck, and my dispatching company doesn't like to allow any truck older than 10 years. They allowed the 2008 because it was a step up from the 2001. The new truck is more difficult to work on than the old truck. I used to be able to check turbo bearing play in about 5 minutes on the '01, but the '08 has some kind of fancy inlet air duct to the compressor that is way more complicated to remove. And the turbo is mounted low and further back in the engine compartment, making access more difficult. There is so much extra plumbing related to the EGR system surrounding the exhaust manifold that a thorough inspection for cracks is impossible.
 
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Sask, Canada
Any codes? All I can do is relay some info from cumminsforum. A guy was having a similar sound on his 2018 and found the turbo actuator was on it's way out. Good luck!
 
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Location
Fort Worth, Texas
The air intake boot isn't to bad to get off..... Disconnect the MAF connector & filter restriction sensor if equipped, Loosen the boot clamp on the filter lid & remove the lid, Remove the air filter, Remove the 13mm headed bolt that holds the filter box, Remove the filter box by pulling it straight up....Out of the rubber isolators. Loosen the boot clamp at the Turbo compressor, Now onto the fun job of removing the Crankcase Vent Hose! Having a spring clamp tool is best, While the clamp is spread open....Try to wiggle the silicone hose off, If no success, You will need a Hose Pick to break the seal. Do Not try to slide the clamp down the hose out of the way as it's crimped to the end of the hose with a little tab! Once the Boot & Vent hose is on the bench.....I cut the little tab of with some side cutters so the clamp can be slid into & out of position making future servicing much easier. I anyone has had any of the intercooler boots off & didn't clean the oil off them.....They will make noise!
 
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7,900
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Michigan
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Originally Posted by clinebarger
The air intake boot isn't to bad to get off..... Disconnect the MAF connector & filter restriction sensor if equipped, Loosen the boot clamp on the filter lid & remove the lid, Remove the air filter, Remove the 13mm headed bolt that holds the filter box, Remove the filter box by pulling it straight up....Out of the rubber isolators. Loosen the boot clamp at the Turbo compressor, Now onto the fun job of removing the Crankcase Vent Hose! Having a spring clamp tool is best, While the clamp is spread open....Try to wiggle the silicone hose off, If no success, You will need a Hose Pick to break the seal. Do Not try to slide the clamp down the hose out of the way as it's crimped to the end of the hose with a little tab! Once the Boot & Vent hose is on the bench.....I cut the little tab of with some side cutters so the clamp can be slid into & out of position making future servicing much easier. I anyone has had any of the intercooler boots off & didn't clean the oil off them.....They will make noise!
I spent a couple of hours chasing down these things. After I got the turbo inlet ducting removed, I pushed and pulled and twirled the turbo shaft, and found no end play or evidence of roughness in the bearings. There was radial play, but that's normal for a turbo with floating bearings. I carefully inspected the charge air boots, and they were all clean, dry, tight, and had no splits in them that I could see or feel. I looked at as much of the exhaust manifold that I could, and found no carbon tracking or cracks. But there is a lot of it that I couldn't see. I have had a thought: How about the turbo inlet gasket? What is involved in replacing that?
 
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