Just something to check, I had a problem with the O2 sensors on the way to Jambo and basically the engine runs very very rich, it smelt of fuel and looked like a diesel whenever I put my foot down, was also using about 60lt/100km which meant it was a stop and fix or I would have gone broke getting to Melbourne
Cheers
Steve
Public Officer - Member #076
Steve
I replaced the O2 sensor (Grand has 4x) and smoke has now gone. Got my wife to stand on a hill and I revved it up and none to be seen. Yipee. Will keep an eye on it though
I did notice on trying to locate this weird noise a small movement in front wheel bearing. Not as tight as left but a slight movement none the less. I'll pull it apart and tighten bearing etc to see if that makes a difference. Problem I have is that I need a very large socket - Off I go to get one tomorrow, shops closed.
Just double check it under load as that is when it will smoke, no load no smoke. As for the wheel bearings, they are in a sealed hub and the whole hub needs replacing, you cant just tweak up the wheel bearings like you can in a lot of vehicles. This is one part of the Jeep that is a real pain as cost wise it's a lot more expensive than just replacing bearings.Originally Posted by SteveC
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Cheers
Steve
Public Officer - Member #076
Thanks Steve.
Could I not just tightening the outer nut? Won't that be possible or am I wasting my time? I can feel some movement once jacked up - in the wheel if I place hands 12 & 6 o'cock and rock it a bit.
Also will diff oil run out or is it a "dry" (in layman terms) axle.
The Jeeps guys seemed to have fixed the seals that reside inside the diff housing as I can see it had been removed and all my expensive RedLine diff oil was used..
I've been skimming through my online Jeep manual and it seems it could be anything - "The axle shaft, differential and pinion bearings can all produce noise"
Oh - I can feel a headache coming on ........
Thanks
The inner seals keep the diff lube in the pumpkin, only in a closed knuckles front axle (or full floating rear) does the gear lube also lubricate the wheel bearings.
Sounds like u-joint failure (although this usually increases both vibration and noise with speed), front wheel unit-bearings (again usually increased with speed) or rear pinion bearing (also incremental with increasing speed).
You said your diff covers were leaking, how low was the fluid. You could have torched the pinion bearing by running the diff dry.
Jack up the vehicle and shake the tire at the 12/6 and 3/9 o'clock positions, you said there was some movement. There shouldn't be any. Unit bearings are expensive, but super easy to replace. Don't let a shop con you into paying labor costs to replace those.
As for u-joints. I assume this humming is happening while you are in two wheel drive? If so try removing the rear drivehshaft and driving the jeep in front wheel drive. If the sounds goes away then it is your rear drivehshaft ujoints. If the sound is still there then it is your front unit bearings or rear pinion bearings.
Good luck.
Wasting your time tightening the nut, the preload on the bearings cant be changed, its a sealed unit and you chuck it when you have wear and replace the hub/unit bearings.
Cheers
Steve
Public Officer - Member #076
Well - Today I removed the front drive shaft and took it for a run. The noise is now gone and smooth as..So I have narrowed it down some what. I cleaned the shaft and reinstalled it and the noise has returned although just a "little" better 10% better. But still there.
Either front wheel bearings, diff or tc or ........
Now at least I can provide some upfront info to whoever I will engage to fix it.
Well - Today I removed the front drive shaft and took it for a run. The noise is now gone and smooth as..So I have narrowed it down some what. I cleaned the shaft and reinstalled it and the noise has returned although just a "little" better 10% better. But still there.
Either front wheel bearings, diff or tc or ........
Now at least I can provide some upfront info to whoever I will engage to fix it.
Grand cherokees (and cherokees and tjs and yjs for that matter) do not have manual disconnect hubs so the shafts, ring and pinion, and front driveshaft are always spinning, even in 2wd. When shifting from 2wd to 4wd, you are only disconnecting the driveline from the front output on the x-case thus not sending power to the front tires. If you removed the front driveshaft and the sounds disappeared (and when the driveshaft was replaced the sound re-appeared) then this should indicate to you that the driveshaft is the culprit because the front hubs, shafts, and ring and pinion were all still spinning.
If grand cherokees are anything like XJs then the front shaft should be a double cardon cv shaft. I would take this apart and repair/clean/re-grease this assembly as well as carefully inspect/replace the u joints on both the axle and x-case end of the driveshaft. This is a good weekend project and the best part is that you can drive your jeep all around town while you repair the driveshaft. Good luck.
I think you're right
My wj has had the drive shaft changed to a double cardan unit from Tom woods, which is a great product . It does have evidence of being scratched and a bit dented from last trip though it looks quite straight...
I thought that mine was 4wd on demand, in other words, front spins/is disconnected when not under load and engages when under load. This may be why when coasting it's smooth and when under load it engages and thus gives me the noise.
I'm a bit at a loss - so Ill need to take it to an expert or someone who knows more about these things...
Any suggestions?
ps I suppose most repairers would be closed around this time of year - bugger
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