I have 103k miles on my 04.5 Dodge diesel. Had to replace a lift pump and that's it so no complaints other than that. Recently though, there is a hissing that comes from the dash area at 2k rpm. If I sustain the engine at 2k rpm, the hissing will continue. But most of the time it's a short hissing while then engine passes the 2k rpm point. It sounds similar to a check-valve popping off, just to give you an idea of what it sounds like.

It does not matter what gear I'm in. Anytime I hit 2k rpm the hiss will happen. It's not as high pitched as the the turbo whine so I'm inclined to think it has nothing to do with the turbo. But I believe something is bleeding off when the engine hits that point...I just don't have a clue what it could be and don't like to take my truck in to get worked on unless I have some idea of the problem. I've searched the forum for this issue but have found no threads regarding this. Any help or ideas would be appreciated.

Mike in Kansas City

 

maybe a vacuum line?? have you checked your intercooler boots??

 

I think yours is new enough that it should have the updated power steering hose, but it sounds just like how mine manifested. I had a kazoo like buzz right at 2000 rpm. It almost sounded like it could be a vacuum line leaking.

After a couple trips to the dealer, I mentioned the ps hose TSB and that cured it.

Is there a weight and a crimped on restriction on the pressure hose from the power steering pump to the hydrobooster? If not, I bet that's what it is.

 

Any luck with the problem?