Low pitched hum/resonance
 

Hello all!
I will try to explain as well as I can, but fire away with the questions, please.
Over the past week we have noticed a new low pitched hum coming from the front end/engine compartment. It is the same in 2wd or 4wd. It happens at greater than 1500rpm whether at idle or moving down the road. It is more noticable going down the road. It also seems to have a rythm to it - kindof a cycling consistent with the engine or a fan. Does not change when the heater is on or off. It drowns out the turbo whistle, but we can still hear the turbo whistle in the background.
We are pretty sure this sounds mechanical and it has never shown the check engine light. Oil is in good shape and is halway up the dipstick. We use good fuel with Stanadyne every other tank.

Any thoughts on what this might be? Thank you in advance.
It has an appointment on Monday to be looked at.

2003 F-350 6.0L FX4 SuperCab 6 speed manual with manual locking hubs, 44,000 miles.

Power steering pump?

I had a resonance at that RPM but it was only after I put the wrong aftermarket downpipe on my vehicle.

Whan you figure it out, let me know...I got the same problem...sounds like it's comming from the air intake...my mileage has gone down too...averaging 11mpg...:'(

SBV45 has the answer becuase I was the first to post it on this site and ask the same question. I thought it was the turbo moan/droan and had the dealer do the turbo bracket exchange (but it didn't help!! In fact it is the power-streering pump "moaning" and is part of the hydrolic system for the brakes as well (or something like that). I had no noise when new, but with 35,800 miles (started at 20,000) it has remained the same.

Two different delaers both investigated and both said it was the power-streering pump. They say it is normal, but I bitched and got a new pump under warranty... and the pump is the same!!!

I am told that that this IS normal (even though it was quiet when new), but after a new pump, it's still there. Did get my lower radiator hose replaced with the new design to prevent rubbing on the streering gear box (there is a broadcast mesage for this ).

Bottom line... new pump, new fluid and "moan" is still there.

If you find out anything different, PLEASE let me know.

Thanks,

Jeff

Thanks.
I finally figured out what it sounds like...a prop jet taxiing down a runway - gets louder and softer.
I will keep those ideas in mind. We also thought maybe clutch fan?
I don't think I am going to accept this as a normal sound as I have to turn the radio up to almost half way to hear over it. They try to chalk way too much up to "normal". Just my opinion. :-)
Thanks all, have a great day!

PS. We are stock except for the bumper.

sound coming from under driver's side
 

I have a new 04 F350 with only 2300 miles on it. Every once in awhile, i will get a sound coming from under the driver side of the vehicle engine compartment that sounds like back pressure being released. It happens when i am up around 2000 or more rpms and let off of the accelerator. I am gonna take the truck into the shop the first of next week just to get it checked but thought i would ask here first. It only happens when i am above 2000 rpms though. Any input is greatful thanks guys

sorry hit the wrong button to post, wrong thread

That is pretty loud, I would not call that normal. Test drive another truck and see if it does it. Have the service manager drive yours and then drive one off the lot.

Well, the sound has gone away just in time for them to parts change the turbo pedestal. Have a feeling this is not what the sound was, but it is gone now (prior to changing anything) so who knows? Thanks for all of your ideas.

Update 2-9-05: Well, it finally broke, nearly died and check engine light! They ended up replacing the fan clutch. Fuel mileage had been getting really bad (comparitively for our truck) and they found a turbo sensor had gone bad - replaced. The thing runs like it did before all the noises started and I even had to turn down the radio to hear the engine! Yeah. :-)

One note, seems there are a lot of power steering leak issues here in the far North when the temperatures dip. Check those fluid levels.
New power steering set up is going in today. Then all should be well for a while...hopefully a long while.
Have a great day all!