Engine/Transmission (1998.5 - 2002) Howling during acceleration

[ESwartzer]

I have a 98 1/2 quad cab 4x4, jammer 2's, helix cam, smarty, intake, 4'' exhaust, airdog, gauges, and stock turbo. It started some months ago and continues to get louder . I have plugged and pressure tested the system with 25# of air and can find no leaks at the boots or the intercooler, and I have even isolated the intake manifold by pressurizing the air horn and manifold together and found nothing leaking. It starts howling at around 10# of boost and then quiets down somewhat as I get into the throttle. My overall boost is pretty strong and I can get into the mid thirties with no trouble. I also noticed a little harmonics going on under the hood that I've never heard before. So what am I missing here? Can a power steering pump or alternator cause a howl when under power, or should I look to the turbo as the problem? I really need some help here! Thanks!

 

[JCyrbok]

I have a 98 1/2 quad cab 4x4, jammer 2's, helix cam, smarty, intake, 4'' exhaust, airdog, gauges, and stock turbo. It started some months ago and continues to get louder . I have plugged and pressure tested the system with 25# of air and can find no leaks at the boots or the intercooler, and I have even isolated the intake manifold by pressurizing the air horn and manifold together and found nothing leaking. It starts howling at around 10# of boost and then quiets down somewhat as I get into the throttle. My overall boost is pretty strong and I can get into the mid thirties with no trouble. I also noticed a little harmonics going on under the hood that I've never heard before. So what am I missing here? Can a power steering pump or alternator cause a howl when under power, or should I look to the turbo as the problem? I really need some help here! Thanks!

I have the exact problem on my 01 have done everything you have done still no idea's. Hopefully someone can help



J-

 

[Sticks]

I should have thought of this before with the other threads involving boos noise.

Get the truck on a dyno. That is probably the best way to isolate engine noise under load. This way you can be standing by the engine while it is under load and locate the noise.

 

[DIESELWRKS]

I know tracking down noises on our trucks are real fun, when you say howl is it a air howl. a howl that starts off light and increases with rpm or boost. also is the howl sound at all metalic, just wondering on your belt and all the pulley's etc. if your satisfied with the air path not leaking. have you checked your pyro plug? your getting full boost so I would think your air path is good it doesn't take much of a leak and you would be getting little to no boost and it would be loud. this sound will it happen when not moving and raising the rpm's at all? hope you find it.

 

[NIsaacs]

How about pre-turbo noise? As in something going on with your air filter or suction hose from turbo to the filter?



Nick

 

[ALepley]

Mine does that but its the engine fan kicking in. Just a thought.

 

[guldam]

I had a mysterious howling a couple weeks ago when I took the family camping. Truck ran fine but that howling had me pull off the road. I looked around, wiggled hoses, but couldn't pin point the noise since the howling stopped as soon as I opened the hood. Doh! Hasn't made the sound since.

Voodoo!

GulDam

 

[JCyrbok]

Mine does that but its the engine fan kicking in. Just a thought.

mine is def not the fan kicking in.



J-

 

[fest3er]

You don't say *where* the sound is coming from. Have someone else either drive or listen for the sound. Is the turbo input connected to a hole in the firewall? Does the sound more match engine speed? Power demand? or vehicle speed?

If it's engine/turbo/acc's, you should be able to put it in4x4 and in gear, stand on the brake and ease down on the go pedal and reproduce the howl. If not, it may not be related to the engine.

Put it up on jack stands, put it in 4x4 and in gear, and stand on the brake. Give it fuel and try to reproduce the sound, slowly easing up off the brake.

Or, as suggested, put it on a dyno. Bring it to any nearby dyno event. If you're lucky, you'll leave with 100 opinions. If you're really lucky, you'll leave with 100 opinions *and* a solution. (Out of any 100 people at an event, at least *one* will recognize the sound and tell you what it is and how to fix it. )

As always with home diagnostics, know what can break, and when. Diagnostics are supposed to find problems, not make more of them.

 

[ESwartzer]

The sound seems to match power demand and doesn't occur until I have around 10# of boost. I was towing my fiver last weekend and did notice that their was some harmonics sound to the howl that matched up a little bit with engine speed

The advice of putting it on a dyno is good advice, but I can't seem to locate one in Northern California. Does anyone know where to find one that can handle trucks?

Thank's guys! Earl

 

[Vaughn MacKenzie]

Have you thought about a turbo upgrade given the other mods you have? Might be an excuse to get one to see if that makes it go away, but then if you're in CA I can understand you wanting to keep it looking "stock"

 

[DIESELWRKS]

The sound seems to match power demand and doesn't occur until I have around 10# of boost. I was towing my fiver last weekend and did notice that their was some harmonics sound to the howl that matched up a little bit with engine speed

The advice of putting it on a dyno is good advice, but I can't seem to locate one in Northern California. Does anyone know where to find one that can handle trucks?

Thank's guys! Earl

what is Northern California to you. where are you located. I'm in southern Oregon and there is on not to far up the coast in Oregon. Imo I would wait on the dyno seems thing to break for me on dyno's in past when I didn't even know I had a problem. have any good diesel mechanical friends, you can also look on the dtr chapters and see how close any of them are to you. a 2nd and 3rd set of eyes are never a bad thing. you would be suprised there are alot of good people on here. and also Harmonic's what are you hearing or feeling exactly. are you leaking oil from your harmonic balancer does it look normal. you can check your belt see if it has a unusual wear to it. next time you change your oil, cut your filter in half and check to see if you have anything in it. does it seem to do it louder or worse towing or empty. do you get any vib's from the steering wheel or feel from the floor boards. check your drive shaft and u-joints. there are alot of weird sounds our trucks make check some of the simple stuff. let us know what you are finding out

 

[guldam]

I believe LeftCoastDiesel.com in Concord has a dyno. Call Erik and see if he can help.



GulDam

 

[ESwartzer]

I've never heard of Left Coast Diesel before Guldam, Thanks for the info!

 

[ESwartzer]

The harmonic balancer might be a good place to look to, I'll check it out. That actually ties in pretty well with the strange harmonics I've been hearing. By the way I'm located in Tracy Ca. 70 miles south of Sacramento.

 

[Ken Roberts]

10lbs of boost huh?

I have had a problem with the rubber boots blowing off the metal tube to the intercooler. After doing roadside repairs more often than I wanted to, I bought the blue silicone boots from Genos. I installed all but the one on the driverside lower, (ran out of time and energy) and did I end up with a howl! At 10lbs of boost that sucker would scream! Yesterday, I had to R&R the radiator and I had great access to the last remaining intercooler hose. I changed it and now the scream is gone. Oo.



Hope that helps.



Ken R955

The sound seems to match power demand and doesn't occur until I have around 10# of boost. I was towing my fiver last weekend and did notice that their was some harmonics sound to the howl that matched up a little bit with engine speed

The advice of putting it on a dyno is good advice, but I can't seem to locate one in Northern California. Does anyone know where to find one that can handle trucks?

Thank's guys! Earl