I feel like it's just one thing after another with this disco.... fortunately I love the thing so I'll tolerate it.

Anyhow it whistles VERY loud if gas is applied when the vehicle is accelerating. When in park I have no noise. I've checked fluids and they're good. The second I lay off the gas even if I'm accelerating down a hill the noise stops. I have noticed on my Torque app through the bluetooth scanner I am loosing vacuum pressure when giving gas to the vehicle. When idling it sounds fine and holds solid RPM

 

Since there is no manifold absolute pressure sensor (MAP) like some other vehicles, how does your app infer such an event? With a traditional vac gauge attached, it is normal to drop vac when throttle applied. There have been posts about plugging the air box to engine pipe with a clean air filter, making the vac noise much louder and easier to find.

 

Im not sure where it is getting its vacuum pressure from but the ecu is reporting it.

 

Ok now that I'm listening to it more, it sounds like it's coming from the back, I was driving at highway speeds and if I let off the gas and re apply gas I get a clunk that I can feel and hear. Also the rear differential is hot to the touch, almost too hot to touch, should it be this hot?

 

Ok definitely the rear axle. I popped the fill plug open and the oil (9k old) is black sludge with metallic specs in it, I'll post pics when tomorrow when I open it.

 

1. Not good. When you service the diffs, also notice the bolt that holds a vent line to the axle, remove and clean that as well. Probably want to go back with 85W150 oil. Service both diffs and the transfer case, and swivels (CVs) if not done in recent memory. If what drains looks like a silver paint mixed with oil that is the gear teeth in liquid form. When is last time the oil was changed in the diffs?

2. What is the reading you believe to be vacuum, and value for it? Perhaps it is part of the EVAP fuel vapor recovery system - on some models it uses a vacuum to check for size of leak in the fuel vapor emmissions system (not the same as engine vacuum).

 

Ok well I think the rear diff is shot, the oil is silver paint with metal chunks. The transfer case fluid is good and so is the front axle. The fluid was changed 9k miles ago.

I'm looking into a new/used diff right now.

You can hear the noise, and you can hear when I let off the gas. It was nasty.


The reading on the vacuum is 26ish, when accelerating heavy it drops to 5ish.

 

Mine was making that noise. It was the perfect pitch and it would reverberate through the cabin and fill your head. I replaced my front differential (had metal sludge in it like yours) and 80% of the noise went away. I still have a little and am thinking it may be a wheel bearing as the txfr case has also been replaced.

Please keep us updated with what you find the resolution to be.

 

Brandon, was your front diff trashed by water in the gear oil?

 

Well I'm going to go ahead and replace the entire rear diff and the bearings inside the rear axle.

Does anyone have any recommendations for where to buy the diff? A new one is out of the questions, way too much unless it is a locker.