Whistle under the hood.

[rfexplorer]

I know this subject has been brought up in the past but I have not heard a solution yet.

I have a 98 sport with Flowmaster 40 series dual exhaust and a KKM intake. My truck makes a whistling sound at about 2000~2300 RPM when Im driving. It doesn't make the when the truck is in park. It only seems to whistle while Im moving. Ive read a few post from others that have reported the same problem but I have yet to find a solution. Please can some one help.

 

[Cameron]

Do you have after market lights mounted in front? What about a grill guard? After market roof rack? CB antenna?

Just some thoughts.

 

[Alec]

For a while I had a slight wistle at highway speeds. It was pretty easy to pinpoint: it was caused by air coming into the cab from the firewall grommet by the brake pedal. It turns out we'd enlarged the hole too much when wiring my accessories. A little electrical tape fixed that problem.

Cameron's questions are good. It could be due to peculiar airflow caused by accessories. I for one noticed my wind noise decrease when I replaced the stock radio antenna with a shorter one.

High pitched sounds can also be caused by loose belts or pulleys. If you're sure it's coming from under the hood, make sure the serpentine belt is still good and check that all the pulleys are on nice and tight.

Good luck!

 

[rfexplorer]

The sound appears to be coming from around the throttle body. If you do a search here for "kkm whistle" there are a number of people with the same problem. I can find no loose vacum line anywhere. I can hear it at 2000 RPM no matter what speed Im going. Its really annoying and it became much louder when I put the KKM in last week.

I have no other accessories. The sound must be from the intake because it became louder when I installed the KKM.

take a look at this thread.

http://www.explorerforum.com/forums/showthread.php?threadid=14863

 

[marowsell]

whistling

I have a stock 1992 2WD Eddie Bauer w/ 170,000 miles I have put on it. The transmission & engine long block were warranted out at approximately 40,000 miles. Within the last 10,000 - 20,000 miles I have noticed the same condition- when I am accelerating and the RPM reaches 2100, there is whistle or almost what I would call a hi frequency ringing sound which seems to come from the center of the vehicle in the area or the transmission/drive shaft. Mystery. No noticeable performance or mechanical problems. Recently as I was driving I heard a similar symptom on another Explorer. I assume this must be some problem on one of the moving parts?
Would appreciate any feed back
M

 

[mikefox]

I also have this noise in my 95. I have heard before that it might be the IAC valve on the intake plenum (sp). I haven't looked into it to much myself, though. Just like rfexplorer says it comes on around 2000 RPM and is noticable until around 2500 RPM no matter what speed your are traveling. Really can hear it good on the freeway. If the RPMs drop or go above the 2000-2500 range the noise goes away. It is irritating at times so I just turn up the radio to drowned it out.

 

[rfexplorer]

KKM response

I emailed KKM about this problem and they sent me the following email. Thought I would share it with the group. I'll let everyone know if any of these fixes work.

Three possibilities;

Dirty IAC (idle air control solenoid), remove and clean passages with Gumout
spray cleaner.

The PCV valve could be gummed up and hanging at just the right opening value
to cause a whistle, clean with Gumout spray cleaner.

Possibility of ..........get this! Crankcase Vent Harmonics, try placing a
small restrictor in the crankcase vent line. Example, the vent line should
be 1/2" diameter, so try placing a short section (1" long) of 3/8" hose
inside current vent line. If the pitch or rpm level changes, this is the
area to address.

 

[rfexplorer]

Just a follow up.

I took KKM's advice and changed the PCV valve but I noticed that the hose that ran to my PCV valve was very loose so I installed some hose clamps on it so it fits snug now. I also cleaned the IAC with gumout.

The noise seems to have stopped! I just took a ride and I can't hear the whistle anymore.

 

[marowsell]

pcv

Any feed back on where I can find a photo or series of visual aids on the web, so I can locate the following:

-PCV valve
-Crankcase vent line
-IAC (idle air control solenoid),

much appriciated,
Marcus.

 

[RammaR]

I've got the exact same annoying ringing noise on my '96. I've the the 4.0L OHV engine, does anyone know where the PCV is located on this combination? The little parts computer at Wally World doesn't list one for the 4.0L engine on a '96. I'll have to make a trip to Autozone for this one probably, but just want to check the hose first.

Thanks.

 

[RammaR]

marowsell,

the IAC is on the side of the throttle body. Its held in place by two bolts. On mine, you can easily reach it from the drivers side of the truck. I cleaned mine last weekend and it had no effect on the ringing/whisitling noise. I've read several posts saying it was the culprit with noises right at idle speeds or a high idle, but our problem is at 2000 RPM.

Although it wasn't the problem, I'm glad I cleaned the IAC - it was really dirty. Just use some O2 safe carb cleaner and it only takes about 10 minutes. No idle problems for sure! I'm going to look into the PCV next....