Hey fellas!

Ok there is my problem. It's a 2002 Excursion 7.3l. I have this hum I want o say at idle. I can feel it in the steering wheel and brakes pedal. It goes away when I give the truck a little gas (basically raise the RPM). The hum I'm 90% sure is from the front but you can hear it resonate to the back.

Here is what I've done so far to tackle the problem:

1. checked to make sure nothing was touching anywhere to perhaps cause it to hum like that

2. Power steering fluid flush

3. Changed Harmonic balancer (while in there changed out tensioner and slapped on a new belt)

Noise is still there. I've researched a little and am led to believe it might be the hydro boost or the power steering pump. I don't want to throw parts at it without some kind of diagnosis.

This is my first diesel truck so I'm learning as I go.

Any help would be great guys! I wanna get this truck in perfect shape for the summer!

Thanks in advance for any guidance.

 

is your exhaust system touching the body or frame any where?

 

I will have to check that. Today I noticed while driving the noise wasn't as bad. I think the colder it is, the worse it is. The noise started up after the truck warmed up (driving).

I looked at the exhaust, and it appears at the end of the exhuast pipe it is a little loose back there. The busing on the hanger doesn't seem to be holding it rock solid in place. I'm wondering if that would case enough of a resonance in the truck.

 

Personally, I would lean toward the power steering pump as well. But, if a fluid flush and change didn't correct the him, it could be something else. I had a similar issue and flushing the power steering fluid cleared mine up. Good luck, I will monitor and see where it takes you.

 

Just to add to the "symptoms".....

When you first start the truck none of that noise is there. It only seems to start happening after you start driving it for a bit. Then the hum starts.

Somedays its a little more obvious then others. I'm really leaning towards something on the exhaust somewhere.

 

You are on the right track. It is either the hydro boost or the power steering pump. My power steering pump is VERY sensitive to a low condition. Even though you just flushed it, check the level and make sure you have it topped all the way off.

 

Just dotting the i's here, but you did use Mercon V ATF to flush and fill the steering pump, right?

Pop off the serp belt and give the pump pulley a spin by hand. Looking for no wobbles and smooth action.

 

Another clue. When the truck is at standard idle, the noise is not there. When the truck sits at park for a bit and the idle goes up the noise goes away.

When I am driving the truck, the noise is never there. Only at low speeds and idle. I'm really wondering if this is the steering pump or the Hydroboost. Brakes are fine, steering is fine. I did use the Mercon P/S fluid.

The mystery continues.

 

when the truck is making the noise,remove serpentine belt to rule out p.s. pump & accessories on front of engine,just dont run very long because your water pump will be sleeping.

 

I was thinking of doing that. What I'm worried about is the fact that usually when the noise is present the truc kis warm. I'm worried if I take the belt off, and the engine is already warm, that I'll cook something some where you know?

How safe is it to do this realistically?

 

just don't run any longer than it takes to listen,its not going to cook that quick, there's still coolant in there.

 

You meant mercon trans fluid right? I didn't know they made P/S fluid itself.

 

Hey everyone! Just dropping a line to let you guys I still haven't figured this one out yet. I haven't had time to try taking the belt off and seeing if the noise was still present.

I keep wondering if this is an exhaust issue. If I am at idle the hum is there, the second I give it a little gas the noise is instantly gone.

Hope to get to this soon!