What is that hissing noise??

[fireman660r]

Well fellas, I got my truck back last thursday, run like a top again. I have discovered a new sound though, and it kind of bothers me. First thing, truck is an 05 PSD F350 CC SWB FX4. 66,000 miles on the truck. This last trip to the dealer was the first major warranty since new. Ended up needing an oil cooler. I now notice a few (usually 2) drips wherever I park the truck, running or not. I am hoping this is just oil from the teardown dripping down and not a leak. I check the oil before I drive anywhere and so far I have put 250 miles since getting it back and it hasn't lowered on the dipstick. Well, on to the new noise. When my truck is sitting idling, even at start-up, there is a hissing noise coming from underneath right around the front doors on both sides. My wife says it sounds like a snake is up in the undercarriage. I compare it to a nail in the tire. I can't hear the noise when I open the hood. I have no power loss, all of the gauges read ok while driving and idling. It sounds like and exhaust leak but I really can smell anything going on. I also can't hear the noise when inside the cab idling and driving. Any ideas ??

[msgtg]

Have you checked the coolant overflow cap to make sure it's tight?

Beyond something that simple, we'll need for one of the pros to jump in and give an opinion.

Good Luck!

Joe

[Dstosh]

Hate to bring up an old thread, but I looked at a truck today that was doing the exact same thing.

'03 6.0 63k

[Ryanr]

I think everbodys does the same, might be fuel system, pump.??

[Dstosh]

After reading some more threads I checked the de gas bottle and I dont think it was that. I read a thread that said it might have been the egr gasket-one symptom was the oil filter housing was covered in soot. This one was covered- I dont know if it was oil or soot. Could be the problem.

I only noticed at idle. not while driving.

[D8chumley]

Could just be the sound of the "older" turbos, mine has an evil hiss at idle but that could also be due to the lack of cat/muffler and the 4" dp to 5" stacks. Theres some videos on youtube that you'll hear it with the 03-04 turbos, that might just be what you're hearing. Does the truck have a stock exhaust on it? Cat/muffler?

[Dstosh]

Originally Posted by D8chumley

Could just be the sound of the "older" turbos, mine has an evil hiss at idle but that could also be due to the lack of cat/muffler and the 4" dp to 5" stacks. Theres some videos on youtube that you'll hear it with the 03-04 turbos, that might just be what you're hearing. Does the truck have a stock exhaust on it? Cat/muffler?

Yeah stock exhaust/cat

[Rizzo66_82]

My 2004 does the same thing, has been since I bought it, Doesn't seem to affect performance.