Attention: TDR Forum Junkies 
LWells
TDR MEMBER
Looking for some education and hopefully insight on a strange noise. Been searching the forums and perhaps it is turbo surge but not sure that all adds up correctly. Here are the details.
I have a bone stock 2007 with a 5.9, original turbo and everything else (except a single replaced injector) with 100k miles. I've noticed over the summer, and in particular on a long trip I just returned from yesterday, a strange noise that sounds like something is revving at a different speed than the engine (I would guess faster but that's a perception not fact). This happens only under hard acceleration - uphill (empty - not pulling anything). As I am going up hill at high speed 70-85mph, Cruise control locked in, I will begin to hear this "fast spinning" noise, as I top the hill it fades away and is gone. Usually when hot outside. Figure it could be the turbo, fan clutch, or AC compressor. Air cleaner is fresh, as is oil, oil filter, fuel filter. Can't make it happen under all hard acceleration.
When this happens I see "normal" readings from my boost and EGT gauges - which would be a run-up to roughly 20-25 PSI boost on the uphill strain with a rapid die off to zero once topping out and going downhill. No wavering of engine RPM, no lack of power, nothing I can feel. Yesterday I drove 14 hours and it never happened under 70MPH, it started once I was cruising between 75 and 85, but only during mid day, didn't hear it at the end of the day (cooler temps).
Two other pieces of info, I hesitate to mention because I don't want to distract but it is part of the puzzle. My boost gauge air supply tube popped off four days ago, has happened once before so no big deal (not a great cinch on the tube end). I put it back on and noticed there was moisture in the line. Once putting it back on I saw boost pressures that day pegging the 35PSI gauge (analog) which I had never seen (occurred with the noise, no other symptoms). But - never saw anything over 25 all day yesterday - like that over-pressure was a one time event.
The reason I didn't think it was turbo surge after reading other's descriptions is because I am running empty, not on any massive hills, letting the cruise control work the throttle so no dramatic throttle let off (I assume). In other words all the conditions are pretty benign. I could imagine pressure collapse happening more often at higher temps/less dense air so that part does fit. Need to pull codes and see if anything there but haven't had a chance. I don't know - any ideas?
I have a bone stock 2007 with a 5.9, original turbo and everything else (except a single replaced injector) with 100k miles. I've noticed over the summer, and in particular on a long trip I just returned from yesterday, a strange noise that sounds like something is revving at a different speed than the engine (I would guess faster but that's a perception not fact). This happens only under hard acceleration - uphill (empty - not pulling anything). As I am going up hill at high speed 70-85mph, Cruise control locked in, I will begin to hear this "fast spinning" noise, as I top the hill it fades away and is gone. Usually when hot outside. Figure it could be the turbo, fan clutch, or AC compressor. Air cleaner is fresh, as is oil, oil filter, fuel filter. Can't make it happen under all hard acceleration.
When this happens I see "normal" readings from my boost and EGT gauges - which would be a run-up to roughly 20-25 PSI boost on the uphill strain with a rapid die off to zero once topping out and going downhill. No wavering of engine RPM, no lack of power, nothing I can feel. Yesterday I drove 14 hours and it never happened under 70MPH, it started once I was cruising between 75 and 85, but only during mid day, didn't hear it at the end of the day (cooler temps).
Two other pieces of info, I hesitate to mention because I don't want to distract but it is part of the puzzle. My boost gauge air supply tube popped off four days ago, has happened once before so no big deal (not a great cinch on the tube end). I put it back on and noticed there was moisture in the line. Once putting it back on I saw boost pressures that day pegging the 35PSI gauge (analog) which I had never seen (occurred with the noise, no other symptoms). But - never saw anything over 25 all day yesterday - like that over-pressure was a one time event.
The reason I didn't think it was turbo surge after reading other's descriptions is because I am running empty, not on any massive hills, letting the cruise control work the throttle so no dramatic throttle let off (I assume). In other words all the conditions are pretty benign. I could imagine pressure collapse happening more often at higher temps/less dense air so that part does fit. Need to pull codes and see if anything there but haven't had a chance. I don't know - any ideas?
