ratsun

I get is a whistling sound under full throttle acceleration. It seems related to high boost? It sounds like air rushing thru a pinched hose somewhere under the dash but there are no lines under the dash for boost or anything like that so..... Anyone have a similar thing?

garbri

Sounds like a boost leak. Check all your intake hoses between the turbo and the engine.

ratsun

All looks good under the hood.
I realy think its from under the dash, not under the hood

Jonesey

I have the same type of high pitched whistling noise. It only does it below 45 degrees or so. I have checked all of the air intake hoseclamps. None were loose. I gave up on finding the cause. Hopefully whatever it is will grenade and be covered under the Cummins warranty before it runs out.

dodgestang

Do you have a boost gauge?
Do you have loss of boost?
Do you have the stock plastic sided intercooler?

Jonesey

No to all of the above. The intercooler is stock but does not have plastic sides. When the paint falls off it is nice and shiney aluminum. It is very hard to tell but I think it may be a bearing in the transmission or pilot bearing. I would think as the engine and transmission warms up it would disappear if it was the aforementioned, but it does not. I changed the transmission and transfercase fluids using Amsoil but it did not cure the whistling noise. Very strange!

ratsun

Yeah its really strange, temp has no affect.
I hope to get my new gauges installed these days off and I will have some more definitive #s to look at as far as boost levels. It doesnt seem like power falls off when it starts making the noise so.....?

ratsun

Well a little more info...it is not related to rpm.
If I run up the rpm to red line with out WOT it does not do it?

jivemother

i got the same thing have no clue what it is .... seems louder now that is so freekin cold out .. some got to know what it is , dose not seem to effect power

ratsun

No it doesn't seem to affect the power in mine either?

Jonesey

It looks like it must be just an issue on 2003s with NV5600s. I sure hope someone can solve the mystery before my 7/100 Cummins warranty expires.

jivemother

mine is an auto

torquefan

It's very easy to pressurize the intake system and intercooler if you make up a pressure tester. There's a picture in my gallery of the one I made. It is worth its weight in gold when it comes to diagnostics. It simply clamps onto the front intake of the turbo and allows you to introduce shop air at 20 psi into the system. If it's a boost leak causing your noise, you will hear it.

I've never tried it on a 3rd gen, but I assume it would fit. The inlet on the earlier turbos is 4".

jivemother

well it got a little warmer today 19 , now the noise is gone . last 3 days been in the neg outside . i dont understand it

rbox

I had a high pitched whistle at colder temps (< 50deg) and I tightened the clamps on the hoses going to the intercooler and it stopped. They felt tight by hand but when I put the socket on them there was plenty of room to tighten.