Turbo hisssss

[Rotorfixer]

Hey guys, did a search, lots of people describing different things, not sure if they are exactly what I am hearing. I assume it is normal, but I remember right at 1000 kms or so it started. Sounds like a hiss, like an air leak noise, that comes from the engine if I load it up. Most noticeable is @ 80 km/h lay into the pedal (not enough to shift), the hiss is pretty loud, also during regen, when it is playing with the turbo it gets pretty load. noticeable enough that my wife asked what it was and said that the engine sounded like a fat kid running....

Sorry to add to all of the turbo noise questions, just would like to be sure! first Diesel, not my fist HD truck (but I did just get rid of my '07 tundra limited... so flame away!)

Thanks for your time.

[blowinsmoke7.3]

Do you have any mods on the truck? Ie; intake, foil delete? Those will cause the noise your hearing

[Rotorfixer]

Sorry, should have mentioned, bone stock, aside from weathertech floor mats, lol. haven't heard of a foil delete for the 6.4 either?

[greasltn]

there is a tube on the drivers side of the engine that supplies air from one turbo to the other right by the fuel cooler. I've seen this happen on one other truck that hadn't been touched, the bolts for the fuel cooler come loose and the tube leaks when you boost. If the tube feels loose just tighten the bolts for the fuel cooler. Hope that's your problem, it's an easy fix.

[Rotorfixer]

Thank you, I will take a look at that! So your guys's trucks don't make a hiss when making boost???

[ZeroOne]

The only thing I would call a "hiss" on mine is the sound it makes when FIRST in overdrive after a slow accel, and then laying into the throttle more but not enough to make it shift. I can hear the turbos "hiss" more as they struggle to make boost at such a low engine RPM (1,300 - 1,500rpm).

My assumption was, it is because the veins in the exhaust side of the variable turbo close tighter, to get the most out of limited amounts of exhaust flow (closing the veins speeds the exhaust gases up as they go through, allowing the turbo to keep its speed up and produce boost)... so you can hear the hiss of the exhaust gases as they pass through this tight gap. As the engine RPM's increase, the hiss goes away, even with the boost at the same level, because the veins can start to open as the exhaust flow is sufficient. I also hear this very quickly between shifts.

[bgulley]

I just had my truck in the shop (08 6.4) for this very same reason. Turns out it was an exhaust leak on the EBP Tube. The dealer fixed it under warranty. Hope this helps...

[sawtooth1]

what is the EBP tube and where is it?

thanks,

[greasltn]

Exhaust Backpressure Tube. It comes off the driverside uppipe and has a backpressure sensor screwed into the other end. Near the fuel cooler bolted to the valve cover.

[SuperDaveF450]

So it is a super loud hiss that comes from the drivers side engine compartment when under boost? I would rather fix it myself (if possible) than have to put the original exhaust back on to go to the dealer. I was towing under light load, hit a bump, and thought the exhaust pipe came loose...wasn't. Sounds like the pressurized air from the turbo is escaping out a pinhole. Thanks for any help.