Odd sound this morning from our WJ Grand Cherokee

On the way to the train this AM, our 2004 Grand Cherokee Limited (4.7 V8 with the Quadradrive 4wd system), made some off noises when we first started off. The truck had been parked over night so it had been sitting for a few hours. As we passed some parked cars, there seemed to be a noise echoing back at the car that I can only best describe as a grinding/low harmonica sort of sound. The truck drove fine, and the noise seemed to get quieter and eventually go away as we drove 3-4 blocks. Any ideas? Wheel bearing going bad? Transfer case(s)? I wish this truck were as simple as my previous TJ wranglers.

Rust on the rotors?

I thought that initially too, but it didn't really have that metallic screeching sound usually heard from that, plus it was while driving, not braking.

I've never felt the WJ to be a particularly complex vehicle, but I guess if you compare it to a Wrangler anything is

Rusty rotors can make noise when you're driving, the pads never really stop making light contact. Was the truck parked for an extended period before this happened?

Eh not super long, parked from 11PM last night till 9AM this morning

Did you try rolling up your windows and turning up the radio?

Wheel bearings don't really go away. Tranfercase could improve as it gets warm and lubricated. Can fluid level be checked? Like was said, rotors, especially if its warm and humid overnight.

Are the rear brake shields wet?

I mean they could be? It's been obnoxiously humid these past few days here in NYC.

I meant wet from diff fluid. Common to have an axle seal leak and gum up the parking brakes and whatever disc side. And then you end up with all sorts of noises and problems

Yup, brake rotors can get a light coat or rust overnight. I've seen it more times than I can count.

I was getting a weird grinding noise from the back of my WRX recently. Pulled the calipers and rotors. I found one of the parking brake springs broken and grinding away against the inside of the rotor!

I don't know if that helps but weird noises abound from brakes!

Sounds like some rotor rust/sticky calipers. Give them a bleed, you probably need fresh fluid anyway.

If you haven't done it in a while, check your trans case fluid. Drain and fill. The unicorn blood in the QD t-cases isn't cheap(I think like $20 a quart, you'll need two), but it's great stuff and REALLY quieted down mine.... that had like no fluid in it. I've posted a picture on here before. It was black, nasty, and I'm suprised the t-case didn't lunch itself. The t-cases are SUPER expensive.

My '99 had the driver rear axle seal go bad, spewed fluid all over the inside of the wheel. Wasn't cheap to fix at 4wheelparts, but they did it quick. It's actually really easy to replace, but I didn't have the tools/time/resources at the time as I had just moved. The bearings are pretty stout, I drove around on mine making noise(Driver rear) for about 2 years. Also pretty easy to replace.

These things ARE ridiculously simple. Aside from the electronics. Those are a bit of a pain. If you ever need to replace a sensor, ONLY go Mopar. Trust me on this. The Crank Position sensor is a REAL bitch to replace.

Yeah our throttle position sensor is on it's way out, which I guess is also very common on these. I need to just bite the bullet and order that part. I guess that one is a little easier to switch out.

And yes, it is unicorn blood, and everyone on the Jeep forum stresses you must use the Mopar fluid in it, or beware. It's the only fluid we didn't get around to doing in a recent service trip.

And by simple, I meant the electronics, which have all been troublesome on this rig. Replaced several switches, harnesses, etc. But, overall, hasn't been a terrible truck, but a little less reliable than the Xterra we replaced this with.

Let me know when you want to sell it Sounds like you've done most of the servicing on it that goes wrong.

Do the t-case fluid, and get new drain/fill bolts. Both of mine were leaking and NOT the OEM ones, instead the PO's thought it was a good idea to just shove a random bolt that may have fit(it didn't) and RTV it over. I was pretty TO'd when I saw that.

LOL I will. And it may be on the sooner side. It's not that it has any big issues other than the aforementioned stuff, it's that we need something a bit smaller and more economical. We keep looking at GTI's, but want to old out for the '14's I think, though we like the A3's too. Total departure from this truck, but we also live in Brooklyn and don't need such a big truck. We barely drive it. I don't think it even has 65k miles on it yet.

You have an Limited, right? 4.7 H.O? Clean underneath?

I'll be sitting on about $7K in Janurary if I don't spend half of it this fall on this POS Accord. I'd love to have another WJ.

Yup, fully loaded with all options, even the (cumbersome, yet relaible) stock navigation system. The only option the PO didn't order was the tow package, which may get rectified with that recall going on. The PO lived in a leafy long island suburb and she basically used it to commute between her house and the commuter train, which accounts for the low miles. Only upgrades we did since we bought it was that we added a set of TJ Rubicon wheels, new Bilsteins all around, and added the Up-country springs.

Have either of you tried the transmission reflash? We had it done to our 2000 WJ yesterday. I haven't driven the truck yet, but my wife reports that it feels smoother and doesn't seem to rev as much. She forgot to check the engine revs on the highway to see if we got a taller top gear.

No, not to my knowledge or the PO. I was thinking about getting this done after we also put the new TPS in. Or maybe we should actually try it before I drop the money on a new TPS.

Quadradrives are full time 4WD, they need the fluid changed in both axles and the transfer case at roughly 35K intervals. If this isn't done, the limited slip additive breaks down and leads to diff chatter which in gentle turns can be described as a moaning noise. Since it uses a center limited slip diff the noise can come from the middle/rear of the car. In bad cases the driveline will bind up and the vehicle will 'crabwalk' the way a conventional 4x4 on pavement will. Change the fluid in all 3 remembering to add the limited slip juice then drive it in figure 8's for a few minutes.

Keith:

I was going to do that in mine by a buddy at his work(Jeep dealership) but they couldn't get their flasher thinger to work. RHF shouldn't need to do it since his is an '04 and has it from the factory. My mom's '02 Laredo V8 was only about 500rpm lower than mine at freeway speeds(both 3.73 tow-package equipped) and had it factory. Hers shifted a bit smoother than mine did, but I had a shift kit/fluid/LB2 line pressure booster. Did you have to pay the $70 fee or did they do the TSB for free?

RHF:

My bet is still on the TPS. A Failing cat made mine do ALL kinds of funny things, too.

Curmudgeon wrote: Quadradrives are full time 4WD, they need the fluid changed in both axles and the transfer case at roughly 35K intervals. If this isn't done, the limited slip additive breaks down and leads to diff chatter which in gentle turns can be described as a moaning noise. Since it uses a center limited slip diff the noise can come from the middle/rear of the car. In bad cases the driveline will bind up and the vehicle will 'crabwalk' the way a conventional 4x4 on pavement will. Change the fluid in all 3 remembering to add the limited slip juice then drive it in figure 8's for a few minutes.

I never experienced that, although I did the t-case and rear diff stuff around the same time, roughly a month after I bought it. Never touched the front diff, but I could feel it working when I'd give it some gusto in the mountains... and sideways on icy/snowy stuff. Every now and again I could feel the t-case shift power to the front and it'd give me a little 'push' when making u-turns, though. These tallboxes can turn REALLY suprisingly well with a decent wheel/tire combo and the QD stuff.

I think I only had it in 4LO once or twice just screwing around on some trails, and quickly put it back into 4HI and let it do it's thing in 1st.

We had to pay for an hour of labor. Took a bit of convincing to get the dealership to find the TSB, it's apparently not easy to pull up. The service writer was game, though, and managed to dig up paperwork that matched what I'd printed off wjjeeps.com.

The paperwork I got when I picked up the Jeep said "Transmission software up to date, PCM is not. PCM updated". So I'm wondering if they did anything with the trans at all. We'll see.

I've gotta say, it's the vehicle I least like in the fleet. Absolutely no road feel in the messy stuff, so it's not a great snow vehicle even though it is almost unstoppable on snow tires. It's a "reverse Tardis", as Car Magazine said years ago. And I've got the Cummins to pull stuff. But it's working okay now that I've replaced the shocks and brake master cylinder. Just a couple of little foibles like a relay buzz from the turn indicator in cold weather.

It's almost silly how much better my QD Limited felt (inside and out) than my mom's Laredo with the selec-trac t-case. Her's was open diff front and rear. Felt like a drunk pig. Mine felt really well buttoned down in comparison, you could really feel the diffs working. With an Addco F/R bar and shocks/springs, I bet that turd could've been really fun to daily. Ever driven a well-sorted '98 5.9 in anger? Those things can HUSTLE for a fat stick axle tank.

Colorado cold weather made mine do all sorts of weird E36 M3. I'd have to drive over the passes at like 2AM in the dead of winter to/from Vail/Denver, sometimes it'd get so cold the heat did NOTHING(thank the baby jeebus for heated seats), the radio would do weird things, didn't like to start, etc. I think I got a picture one time when I stopped at the top of Vail pass with the exterior temp reading -40. You're absolutely right about it being unstoppable in the snow, though. Even on my crappy rockish OE Camaro all-seasons, I couldn't get mine to not go up the side of a building.

On the trans reflash, you should be able to find out if/when it was done previously just by giving them your VIN. Only an authorized dealer can do it. I'm betting they did it this time around. You can feel it go into 5th pretty softly at highway speeds, then feel the TC engage. Try hitting the button on the shifter to turn off the TC before merging onto the highway from a stop, row it through the gear slots manually, and count the shifts. The 4 and 5 shifts are pretty close, but with the TC lockup disabled, you should be able to tell if/when it gets into 5th.

We don't drive on the interstate often. I'm not sure it's been up to 75 since the change. But Janel has reported there's a definite change in the transmission behavior and it appears to be for the good. I doubt it had the TSB before, she bought the thing new and the required sticker was not underhood. Plus the highway revs didn't match up with what I expected for a post-flash trans.

This one is a Laredo. It's not an offroader, it's only ever seen two (fairly mild) offorad trip in its life when we took it over Engineer's Pass and Imogene. Probably didn't need 4WD for either trip, just some ground clearance. So I'm looking at it as a street vehicle, and I'd much rather see an Outback in the same parking space for that use. You're looking at them as offroaders - but really, they're kind of an uneasy middle ground where the truck is compromised for both uses. But like I said, she bought it new so she loves it.

Totally agree on that point. It's more of a own-it-because-you-love-it thing. There's much better options out there for 90% of the application that these actually see.

I'd still take my old one back in a heartbeat.