If it is the hubs (vaccum) why would it be louder under load?

I am waiting for it to become more prevelant and it is. Seems as though we can hear it more on almost every acceleration.

Seems to be heard after warm-up and not until then. So would vaccum lak only be heard after warm up?

That's why I think heat shield - expanded after warmup creating loose weld, whatever.

 

I know exactly what you mean. I have had the same noise for about a year now on my 04. I checked everything and can't find it from underneath with banging the exhaust and heat shields. It drives me crazy and it is only under load / acceleration at certain speeds. I swear it is something rattling in the muffler or a loose baffle inside but can't make anything rattle when I shake it. Pretty steady about 120 kmph (75 mph) up a slight grade though. If you ever find the cause "Please" let me know. I will watch this thread carefully.

 

What kind of fuel are you running? You say it's under a load, and when the engine is hot. With the amount of soundproofing in the firewall, an engine ping (pre-ignition) would resonate through the floor...Just a thought.

 

When the engine is under load, the manifold vacuum is lower, so if there is a leak in IWE system somewhere, the lower vacuum level can not keep up with the leak and the IWE's try to engage.

A fairly easy way to eliminate the IWE's clattering as the source of the noise is to disconnect and plug their vacuum source so they are always engaged. Make sure they are engaged by trying to spin the half shafts, and take it up that hill again to see what happens.

 

It's your BUG DEFLECTOR!!! Seriously...What kind of gas are you running?

 

Might be - but my bug deflector is on the front not under the right rear.

 

I was being facetious about the bug deflector...I hadn't read that it was in the rear of the truck the first time when VFR was talking about the 4X4 IWE possibly being the cause. That said, hell if I know...

 

Definatley not a ping. It's a rattle.

 

Took another tech on a ride. Less than a mile from the dealer I was able to replicate the rattle. We went back to the dealer and less than 2 hours later they called and said rattle was fixed.

It was a heat shroud that upon expansion (only after warm-up) would touch the transfer case. Once the resonance hit the right level, the rattle would sound off.

they moved the heat shield and now we are good to go.

tech said you just had to llok in the right spot. he could see a wear/rub mark on the transfer case from the shroud.

Only took 4 trips to the dealer to get it taken care of.

Thanks for the input guys.

 

I will crawl under mine and look tomorrow. Thanks for the tip.

 

I'm having a similar rattle, but I'm able to reproduce it while in park if i gun the engine real good. I suspect a heat shield, but I'm worried it could be a valve clearance problem. I dont know if it could be related but I'm getting 3 codes from the 4x4 control:

4x4 Control
P1707 Park/Neutral Indication Circuit
P1836 Transfer Case Front Shaft Speed Sensor Circuit Failure
P1837 Transfer Case Rear Shaft Speed Sensor Circuit Failure

I'll make a new post to find out, but if you guys have any thoughts, let me know. I plan on getting dirty under there this week, I just havent had time to get to it and I've not noticed any other symptoms.
-RPM

 

My Explorer had the rattle from the heat shield. I seemed to notice it more than anyone else, but it was there and worse at certain speeds. I took it back to the dealer, they heard it, and fixed the loose heat shield.

 

Very interesting thread .... I too have this crazy rattle. the interesting thing with mine, is I let it go for a bit longer the other day climbing a hill to see what would happen and it got to the point where it was almost a loud hissing noise. That said, I still have no idea.

My first trip to the shop my mechanic thought is was the heat shield, and on my way home it started again (awesome), it's back again, he's thinking transfer case now?? yikes ...

I will update as i learn things, but my issue sounds very familiar with whats posted;

mostly under load (ie pulling my boat)
no apparent loss in power
Loud, and gets louder and more prominant as you let it go
Let off the fuel and it gfoes away until your back on the fuel for a few seconds
Mechanic said it didnt occur in 4x4 (but he also said it was the heat shield last time - haha)

I will update as my bill grows - haha ***** ....

 

Okay .... I'm fixed!!

So, after days of trial and error, we changed the solenoid, didnt fix it, so we changed the IWE actuator and that got it.

Point of note. The actuator that was the problem was NOT the one making the noise. Passenger side was leaking, but drivers side was the one that was chattering/grinding/rattling ....

Regardless, beat on it all weekend, hills, towed boat etc, no noise....

hope that helps someone out there!