Archived high pitched sound while under boost all of a sudden

[JCyrbok]

Yesterday while driving back from a family vaca in florida my truck (see below) developed a high pitched sound (oddly actually sounds like electrical interference, but its not, LOL) once boost hits about 9psi.



The sound goes up and down with rpms and boost and sounds like its coming from the drivers side of the engine. Under 9psi the sound is completely absent.



My boost, egt and all other gaugaes are running where they should be and everything, atleast to my naked eye seems fine. All fluids are good and do not appear to be contaminated.



Here is the kicker, while running through Macon GA on the way back, I lost my water pump and had to have the truck towed to a dealer and had the pump replaced and a flush and fill of the coolant system done (nice $820 kick in the crotch on the way home eh, especially since the pump is about a 10 minute job in the driveway#@$%!#@$%!, but we were in no position to argue LOL).



The noise did not start until about 400 miles later and seemed to start or atleast I noticed it while entering the higway from a rest stop (so boost was up). I'm thinking (hopeing actually) that the noise and the water pump are just crappy coincidence.



I'm thinking boost leak from some where (my guess is maybe the intake horn gaskets).



Anything else I should check. Hopefully its nothing big, but guessing that with the truck running normally other than the sound it is not.



we got in at about 0330 and I havent had a chance to check it out yet (next thing on my list, LOL).



Thanks in advance for any help



J-

 

[p-Bar]

I think your on the right track sounds like a boost leak heard of guys spreading shaving cream on all the joints and running the truck . Sorry to hear about the water pump maybe belt tension? I assume you got no complementary reach around when paying the bill?

 

[JCyrbok]

I think your on the right track sounds like a boost leak heard of guys spreading shaving cream on all the joints and running the truck . Sorry to hear about the water pump maybe belt tension? I assume you got no complementary reach around when paying the bill?

nope no joy on the bill, but I figure they got me in and out the door in about 2 hours and back on the hell of a drive that it is from FL to MI. Thanks to Five Star Dodge in Macon GA.



I think that the pump just gave up the ghost, it was the original on the truck and I have just over 100K.



As for the noise, went out today and re-torqued all the bolts on the intake and intake manifold (that I could reach) some were a tad loose but the sound it still there. Thanks for the tip on the shaving cream I'll give it try.



J-

 

[Sticks]

Visual inspection of the lower intercooler boots, particularly on the fender side.

You may need to pull the intake hat and grid heater and check the gasket(s) itself for any splits.

Check your idler pulleys and alternator as well.

 

[JCyrbok]

Visual inspection of the lower intercooler boots, particularly on the fender side.



You may need to pull the intake hat and grid heater and check the gasket(s) itself for any splits.



Check your idler pulleys and alternator as well.

copy thanks, i'll get under the truck and check the boots real good and also check the gaskets (probably just replace them for s/g's)



Idler and alternator appear to be find to me (that was one of the first things I checked).



I went and washed down the engine compartment yesterday as it was COVERED in coolant so I will see if maybe a clean engine will show where the leak may be too.



Also is there a way that I could disconnect/bypass the vacum pump intake to rule out a vacum leak in one of the vacum lines?



J-

 

[GAmes]

Also is there a way that I could disconnect/bypass the vacum pump intake to rule out a vacum leak in one of the vacum lines?

You could disconnect the big line going into the pump and cap it off. That is the "intake".

 

[JCyrbok]

You could disconnect the big line going into the pump and cap it off. That is the "intake".

copy thats what I figured just wanted to be sure.

J-

 

[JCyrbok]

checked some stuff, sound still there.

What I have done so far with out any success:



1) checked for a vacum leak by disconnecting the main vacum line from the pump. Sound still there.



2) checked the intercooler boots (no obvious holes or leaks), retightened all clamps, sound still there.



3) replaced the two intake air gaskets, retourqued the bolts to spec and also retourqued all the intake manifold bolts I could get my tourque wrench on. Sound still there.



4) on the off chance that it was the idler pulley (heck it was the original after all) I changed it out with a new one. Sound still there.



5) check the turbo for execesive play or signs of oil getting past the seal and everything looks good to me.



One thing I noticed is that if I slowly let the boost build up to around 10-12psi the sound starts and will continue until boost goes under that . BUT if I get on it hard and the boost rises fast it briefly makes the noise at/around 10 psi and then stops as the boost rapidly climbs. If I stay in it, like on a freeway entrance ramp the sound does not start until boost falls back to around 10. The intermintent nature in this sense has me stummped.



Started looking for other causes since I have done everything I can think of and was wondering if maybe this is a wastgate problem? Either sticking open or closed? (doesnt make sense as the boost readings are the same as before the noise started). Would there be a problem if I shot the linkage and connections with some PB blaster while it is cool? I noticed that even though I had rinsed off my engine bay after the water pump was fixed there was still some sticky scalely coolant residue on some places, maybe its gumming up the waste gate?



Also no obvious signs of leaks since I rinsed the engine off last week.



Other than that I am at a loss. Any other ideas????????



J-

 

[Bob4x4]

The best way to find a small (whistling) boost leak is to pressurize the system. It will also be the fastest way to find it

 

[JCyrbok]

The best way to find a small (whistling) boost leak is to pressurize the system. It will also be the fastest way to find it

copy, what is the best way to do that, I'm thinking make up a pvc cap with a tire stem that attaches to the system with a rubber coupling then pressurize with compressor? Is there a max pressure that I should stay under this way?



J-

 

[DieselDoghouse]

WOW Dude! Helluva Vaca?!! You're home…that's what counts (think if this had been in a gasser??). So - the noise didn't start til after the pump change?? My Dad (I'm channeling) is suspicious of the last thing done (he always was). Lets assume that the water pump change led to—intercooler hose loosening, dislodging, tool damage to the intercooler core (OK I'm reaching) from a tool. I am just guessing but it looks like bypassing the 'cooler or going natural aspiration is next to see if the noise persists???. Let us know. BTW what gauges and what are they saying?? ( I dropped an intercooler outlet clamp one night after work—sounded like I was in front of the worlds biggest Dyson—BUT my boost never went above 5 psi so I knew).

 

[JCyrbok]

WOW Dude! Helluva Vaca?!! You're home…that's what counts (think if this had been in a gasser??). So - the noise didn't start til after the pump change?? My Dad (I'm channeling) is suspicious of the last thing done (he always was). Lets assume that the water pump change led to—intercooler hose loosening, dislodging, tool damage to the intercooler core (OK I'm reaching) from a tool. I am just guessing but it looks like bypassing the 'cooler or going natural aspiration is next to see if the noise persists???. Let us know. BTW what gauges and what are they saying?? ( I dropped an intercooler outlet clamp one night after work—sounded like I was in front of the worlds biggest Dyson—BUT my boost never went above 5 psi so I knew).

I first thought about the water pump but the noise didnt start till about 5-6 hours after it was changed.



Boost/EGT are SPA digital and are running where they normally do for both boost and egt, which is odd to me since I would think that with a boost leak the boost would be low and the EGT would be high, but they're not.



Gonna try a pressure test on the boost system and on the off chance I'm gonna change out my air filter (UNI Foam in a scotty II housing).



Thanks



J-

 

[Bob4x4]

copy, what is the best way to do that, I'm thinking make up a pvc cap with a tire stem that attaches to the system with a rubber coupling then pressurize with compressor? Is there a max pressure that I should stay under this way?



J-

The amount of pressure allowed is up to the strength (safety) of your test rig. Mine is aluminum and has a safety chain. I have gone as high as 50 psi for a perfomance built truck. I have seen many leaks that won't show till over20 psi. Be carefull... ... ... .

 

[JCyrbok]

The amount of pressure allowed is up to the strength (safety) of your test rig. Mine is aluminum and has a safety chain. I have gone as high as 50 psi for a perfomance built truck. I have seen many leaks that won't show till over20 psi. Be carefull... ... ... .

copy thanks Bob.



J-

 

[JCyrbok]

could it be the waste gate??

Anyone think that it could be a sticky waste gate causing the noise??



J-

 

[Sticks]

Anyone think that it could be a sticky waste gate causing the noise??



J-

Don't know. Have you pressurized the intake system yet?



A wastegate that is barely cracked open may be able to whistle, but I am not sure that it would be audible anywhere but the tailpipe.

 

[JCyrbok]

Don't know. Have you pressurized the intake system yet?



A wastegate that is barely cracked open may be able to whistle, but I am not sure that it would be audible anywhere but the tailpipe.

gotcha. I'm gonna pressure test it this weekend.



The one this that it really confusing to me is that if the pressure comes up slow the sound is there until I let off the accelerator. If I stomp on it the comes at abotu 12psi and goes away at about 17psi as it climbs to 22psi (max on my truck right now).



If it was a boost leak I'm thinking that it wouldnt go away? But we'll see when I pressure check it, if I have a break while doing front wheel bearings, :{:{:{ LOL



J-

 

[DennyDay]

Just a chance - - check the boost hose where it connects to the boost gauge - - had a hose crach a couple of years ago and got a whistle - - - sounded like it was coming from the right side of the engine but it was in the door post

 

[msperos]

My Pyrometer probe started leaking when i was pulling the 5th wheel but not when empty and it made a whistling sound from an exhaust leak just below the turbo. Seems like the manifold is expanding at a different rate that the probe fitting. I put a steel pipe plug in place of the probe and had the same thing, fine when empty but whistling when pulling heavy. Just a thought

 

[JCyrbok]

copy thanks guys, boost gauge is electronic so there is no tubing involved. I check to make sure that the sender is not leaking somehow.



As for the pyro, the sound is definately coming from the passenger side.



J-



Opps driver side