High Pitched "Cricket" Buzz

[Brubro67]

Hello,

 

I have an odd buzz or hum coming from what appears to be under the driver's area hood which projects through the driver's side dash.  It sounds like a relatively loud high pitched cricket buzz.   It started under load, but sometimes continues (more often now) during constant throttle.  If I back off on the throttle, it most often stops.  It seems to be increasing in frequency but sometimes does it very little.  Since it happens only when driving, I can't pinpoint the issue.  It is definitely not loose metal, heat shields, exhaust, etc.  It seems electronic, tied to throttle response.  I've searched on line with no luck.

 

Any ideas?

[Mopar1973Man]

Error codes?

 

Fuel pressure?

 

Injector line hold downs?

[Brubro67]

There are no error codes.  Injector pressure is fine per Ultragauge info.  Injector line hold downs are fine.  No fuel leaks, or other obvious problems.

 

I haven't tested lift pump pressure, but there is no delay in start (extended cranking) etc.

 

BTW, truck has about 160K, only mods are aftermarket exhaust that I know of.  There is nothing obviously modded other than that.  Link on testing fuel pressure?  I will do a search when I get home if you can't.  Thanks!

[Mopar1973Man]

Boost leak?

[Brubro67]

Not that I can tell.  Runs great overall.  Had boost leak issue with '98.5 that I owned prior to this one.  That was obvious and I still have my homemade intercooler pressure tester.  Haven't bothered to test that since it runs so well.  No drop-off of performance at all.

 

It really sounds surprisingly like a loud cricket.  It happens when accelerating, and I can make it stop usually by backing off the throttle.  If I accelerate slowly, it usually doesn't happen.  Sometimes it is normal under moderate or heavy load too.  Truck is used  primarily for hauling 10K loads on average, but it also does this when unloaded.

[Mopar1973Man]

Power steering fluid full? I'm thinking of all the devices on the driver side.

[AH64ID]

Check to see if the damper is still installed on the high pressure power steering line. 

Edited February 12, 2019 by AH64ID

[Brubro67]

Power steering fluid is at level.  Dampener is in place.

 

Understand that all of this is reference to my view point, IE, the driver.  So, I understand that although it appears to me that it is coming from the driver's side, that may be a matter of perspective.  Wife thinks it is coming from drivers side too though, when in passenger seat.  It is one of those noises that is very hard to pinpoint.

 

Here are two wav files.  On "1" I was able to generate and capture the buzz.  That happened to be my first attempt.  I tried several times after to get a better audio recording, and the truck won't replicate.  This is my nightmare.  You can hear that it is tied to throttle response.  I didn't mention that it never happens in 3rd of overdrive.  It is always 1st and 2nd.  Once you are up to speed, if it happens (I can't recall), it is very rare.  It does not matter if it is warmed up or not.  There is no difference that I can tell with engine temp.

 

I completely rebuilt the tranny a little while ago with upgraded components such as billet torque converter, etc.  It was a mild upgrade, simply for reliability for hauling, not performance.  I don't need a race truck.  This made no difference or change with the noise, although the frequency of it occurring did seem to have increased slowly over time.  ...Or, I am more cognizant of it.

Cricket 1.wav

Cricket na.wav

 

I just listended to the files here.  You can hear it but not as obvious as on my phone.  Maybe use headphones?

Edited February 12, 2019 by Brubro67

[JAG1]

Turbo damage or has bearing play? bad Idler pulley?

[AH64ID]

 I cannot get the file to play on either my phone or computer. 

 

If it only happens in first and second gear I would suspect one of two things. First it’s in the transmission, and second road noise masks it at greater speed’s.

 

Have you driven around locked in second gear and created a way to re-create it on demand?

[Brubro67]

51 minutes ago, JAG1 said:

Turbo damage or has bearing play? bad Idler pulley?

Turbo is fine.  No play, rock solid.  I'll check idler pulley, but I don't see slop when engine is running.  Will check though.

28 minutes ago, AH64ID said:

 I cannot get the file to play on either my phone or computer. 

 

If it only happens in first and second gear I would suspect one of two things. First it’s in the transmission, and second road noise masks it at greater speed’s.

 

Have you driven around locked in second gear and created a way to re-create it on demand?

Strange; it is a wav file, works on both my computers.  Anyone else having this problem?  Can I email it to you or something?

 

I can't imagine that it is the transmission, not coming from that area at all.  It definitely sounds electronic.  Plus, it started before complete tranny rebuild by a very competent shop and didn't change at all afterwards.  It just slowly got more frequent in occurrence.

 

Road noise could be issue, but I am pretty aware of it and it just seems to be an issue under roughly 45 mph.

 

I can usually create it by putting engine under medium load, but it is sort of hit or miss.  It did it on the first attempt to record, and a few times after but recorder didn't capture properly; too much wind noise.  Then the truck just refused to do it on several more runs.  it is baffling.  If it was tranny, turbo, pulley, I can't imagine it would be that random, but what do I know.  All I can say is that this is the MO.  Drove it around an entire weekend and it hardly did it at all.  Monday morning, sort of non-stop until it got to speed.  No power issues, everything runs perfectly, all ultragauges, codes and alerts show everything is normal.  Sounds sort of like bad relay or other electrical component starting to fail, but I know there aren't relays on this vehicle.

[JAG1]

Take and squirt a shot of W-D40 at the idler pulley bearing. See if it goes away.

[Brubro67]

47 minutes ago, JAG1 said:

Take and squirt a shot of W-D40 at the idler pulley bearing. See if it goes away.

Will do.  Worth a shot.  Thanks!

 

Doesn't sound like a pulley, but worth a try.  Bad pulley is usually more of a squeaky, sometimes clanky noise.

Edited February 13, 2019 by Brubro67

[AH64ID]

Hopefully that does something, but the accessory drive has no clue about load, road speed, or what gear you’re in. 

[Brubro67]

28 minutes ago, AH64ID said:

Hopefully that does something, but the accessory drive has no clue about load, road speed, or what gear you’re in. 

That's my thinking too, but need to check them for play anyways.

[Brubro67]

Been busy but here is either a development or coincidence:

 

When I checked the power steering fluid, mentioned by Mopar1973Man, it was about half way between full and add.  So, I topped it off.  Since then, it seems to be doing the cricket buzz less frequently.  I will do a full fluid exchange this weekend and see if it makes a difference.  The fluid does not look fresh, so it needs to be done anyways.

 

Has anyone heard of the hydro-boost making noises before other than what I consider the standard "hiss" which stops when the brake is applied?

[SilverMoose]

Feels good to back posting.  It's been way too long and I have been way too busy to be away from this great forum.

 

Anyway I helped my buddy @Brubro67 flush his power steering fluid today.  He came back and the noise was still there so I went for a ride with him.  The noise did come back but for a short time.  To me it sounded like a high pitched squeal like a belt slipping or a bearing.  When we got back the fluid was low probably from getting the rest of the air out of the system. Hopefully topping it off will take care of it. I wonder if there's anything in the hydroboost that could make a sound like that but I doubt it.

 

We agreed that he should take the belt off and check the power steering pump to see if the is any play in it or feel if a bearing is heading south.  He will also check all others pulleys to make sure they are good.  I'm glad it doesn't do it constantly because it was very annoying.  Hopefully he can narrow it down this week.

 

Glad to be back and hope stay.

L8tr

d

P.S.

@Mopar1973Man I hope you are feeling better

[Mopar1973Man]

Fan belts can do weird things too if the belt is too worn between the ribs it can make random noises at different RPM's.

[SilverMoose]

31 minutes ago, Mopar1973Man said:

Fan belts can do weird things too if the belt is too worn between the ribs it can make random noises at different RPM's.

I'm pretty sure it's new.

 

L8tr

D

[Alterego]

The truck you have listed is a 4x4 right. It might sound far fetched but I have seen it before. The pinion bearing can make sounds like that and project up and sound like a belt or idler going bad. They usually act up when loaded and then quit when unloaded. Being that these trucks(at least from the ones I've delt with drive the front drive shaft all the time, when you accelerate it loads the pinion then when you let off it unloads and quits making noise. Check your diff fluid and play in the pinion could be a bad u-joint as well, but I have seen pinion bearing do crazy stuff on the big 4x4's I use to build.