Whats this noise?

toddsnorthriver · 07-19-2008, 09:29 PM

I have a 2004 f350 diesel that has developed a flutter when letting off the accelerator under a hard acceleration like pulling a boat up a steep boat ramp. It has done this from day one but now it did it the other day when I was towing my 5th wheel home from newport. Driving under normal type condition, letting off the accelerator with the flow of traffic caused the loud flutter type sound that I only heard under a heavy load. Any Ideas? I know its normal under hard acceleration but normal type driveing? Thanks,Todd

willierower · 07-19-2008, 10:39 PM

Waste gate on the Turbo??? Do the Powerstrokes have a pop off valve that releases the excess boost when the throttle closes?

EvilD · 07-19-2008, 11:13 PM

Turbo bark. Not good. It is pressure surging back into the turbine housing past the impellers. When you chop the throttle at WOT or close to full boost the pressure regulates itself through force and causes pressure to spike backwards instead of down the tailpipe. It will cause problems down the line, shorten the life of the turbine and cost a lot of money to repair. The best solution is a wastegate of some sort. The other solution is to ease out of the throttle. DO NOT chop it, let off slowly and let the pressure compensate.
My duramax started doing this after I added a 5" exhaust and cranked the boost up to 30psi. I actually have two new sounds; one is the hot exhaust escaping and cold air rushing into the tail pipe at the same time creating a whistle of sorts, and the other is the turbo coughing when I let off (chop) the throttle at 22psi or more.
Under normal driving conditions with a stock tune and exhaust there should not be any turbo bark or flutter, there shouldn't be enough boost. Towing is another story. Adding a load, the vehicle will sense the speed and throttle position and compensate by increasing turbine pressure, possibly causing the noise. I am, however, not totally familiar with the 6.0 power stroke diesels. Also without gauges it is hard to pinpoint the conditions which bring about the undesired noise.

Happy motoring and power to the oil burners!

D

Cliff D. · 07-20-2008, 06:37 AM

It's the sound of dollars leaving your wallet !!

Lou · 07-20-2008, 07:13 AM

Any check lights on?
Mine did that and it was fixed under warrantee.
Can't remember what it was, they charged Ford
380 bucks. The check engine light did come on.
I have a 04 F350

WaterDog · 07-20-2008, 07:39 AM

Todd head over to "thedieselstop" and ask or search over there. Your PSD is a 7.3?

There is "turbo surge" that sounds like pressure cooker "pst pst pst" sound that happens under a hard pull usually loaded. This is bad.

There is "turbo stall" that is sort of sound like what your describing which is a "whooshiing" sound after you let off the accelerator or when your tranny shift under a hard load. Stall is not that big of deal.

You don't say if you have any mods like a chip, programmer, open intake, or exhaust mods. All of this will make the above more noticeable.

toddsnorthriver · 07-20-2008, 09:32 AM

The common thing I'm hearing fromo other sites I've checked is back pressure on the turbo. They have all said it would be eliviated with a waste gate of some type but this motor dosen't have one. I understand it will do it under a heavy load on the motor like leaving a boat ramp or pulling a heavy load up a incline from a dead stop, but normal hiway driving, slowing down and speeding up with the flow of traffic gradually? And why would it stop after I shut the motor off on a refuel? Vanes getting stuck ? Thanks,Todd