Turbo Noise!! Help!!

[Fireman40]

Can anybody help me? I have put in a few post but no good responses yet. When Im doing hard take off even without a load I get a wizzing noise from the turbo. Its a difficult noise to explain. It only happens when my Rpms are about 2000 for a few seconds and im really layin on her, then it will kick in. Its like the engine looses power and sounds like the turbo speeds up. I just let off the gas a bit and it stops and goes back to normal. It doesn't bother me for normal driving but it makes it hard to take off pulling heavy trailers. Im afraid this is going to ruin my engin. Any Ideas?

[welder4020]

is your tuck a 6 speed and if it is does it do it in any gear or just high gear?

[Fireman40]

No its five speed auto. And it always happens in fourth right before shiffting into five. It dosesn't happen during normal driving. But when Im really pushing on her if holds out on the last gear a little longer and thats when I get this noise.

[welder4020]

is there any change in rpm when or before it does it? i'm just brain storming trying to eliminate some possibilites

[Fireman40]

No there is no change in rpm that i see on the tach. I assume the loss of power is because it no longer has the boost from the turbo. I have held on it before to see what it does for a few seconds, and it doesn't seem to regain the boost or normal operation until i lef of of the pedal. Someone had said something about maybe its defueling but what would cause that.

[superduty4x4]

You don't have a 5speed auto, its a 4speed. I can't offer any advice, but it sounds like trans slip to me.

[Fireman40]

Thanks for the info on my tannie. I never really knew if I had a four speed or five speed. I had thought about this problem being a trannie slip but I didn't want to think it. The guy who owned the truck before me had it rebuilt once. (snow plow). I bought the truck with 70,000. I had it rebuilt once at about 90 and again at about 113. i sure hoped after the third time and them telling me everything was good that It would be going out again. Is there anyway I can stope this slip without having to rebuild again.

[superduty4x4]

Well, if you are feeling something weird going on but the RPM doesn't jump when it happens, it might not be trans slip. If you were defueling (caused by overboost) you would be setting a check engine light.
Do you have gauges in your truck?
Oh, and the reason your truck feels like a 5 speed is because between gears 3 and 4 the torque converter locks up, so it feels like an extra shift

[Fireman40]

No I don't have gauges, but after reading alot on here I really think it would be a good idea to get them. Atleast I would be able to see what my boost is doing when I hear this noise. But anyway thanks for your help

[superduty4x4]

Knowing what the boost is doing and the trans temp would help to know if it's trans slip or not. Good luck with figuring it out!