The Jeep boards are about as useless as tits on a bull.

Vehicle: 2011 Jeep Grand Cherokee Limited AWD, 69k Miles

Problem: Cruising between 40-50 MPH we get an annoying humming sound from what seems to be the front end.

Post Inspection: Her mechanic said it needs struts, tires, and alignment. Said the humming is from the tires being worn unevenly and they will make a hum at highway speeds due to them being aggressive tires, Cooper Discoverer A/T. Quote came back to $2000.

Now I know they will make a hum at highway speeds, all knobby tires will. Here is the part I don't understand, he told her she needs new tires before getting an alignment. Yes it will help with new tires to have it aligned right after, but why does she need them before the alignment? Don't they measure off the rim? Also, I don't think the alignment being off would create such a HUM at those speeds mentioned above. If anything it would prematurely wear a wheel bearing by chance, correct? Never mentioned anything about a wheel bearing. Her family all use this guy and always say "What ever it takes, just fix it". Who knows what he is replacing that doesn't need to be replaced.

I have some mechanic buddies myself so I may have them inspect it and see what they say. I would trust them over hers any day since I personally know my guys and would hope they wouldn't be giving me the run around.

We are looking in to selling the Jeep and would like to get the most we can for it but with that sound, I feel after a test drive all potential buyers will be turned away or knock the price down significantly.

Any and all input would be greatly appreciated. I don't want her to get screwed over since she doesn't want to listen to me.

 

You are correct, new tires aren't needed for an alignment. Switch the tires front to rear and see if the noise fol!ows the tires, or still in front. The front d/s isn't the best, as well as the front diff bushings. In fact just replaced the front d/s and did the diff bushings on the daughter's hemi-grand.

Without looking at the Jeep, I'd say with that mileage all those items aren't needed. Nothing more than throwing parts on the vehicle. Look for another mechanic.

 

Propeller drive shaft bearing, or worst its the transfer case that making the noise. The reason why most place tell you get new tire prior to alignment because the factory alignment specs base on a car that has new rubbers and aligment specs does move as your tire wear down.

 

The alignment has nothing to do with the tires. The alignment equipment attaches to the wheel and has no bearing on the condition of the tires. The reason the tires wear is because of the suspension that is out of spec, not out of spec because the tires wear.

The reason why they would like new tires before alignment is that if the old worn tires remain on the vehicle and an adjustment has been made to correct the caster, camber, toe, it changes the position of the tread where it meets the surface of the road and therefore could possibly cause vibration, wondering, stability etc. depending on the severity of wear.

 

Thanks for the replies! I will rotate the tires and see if the sound follows, I don't think it will but only one way to find out. Also, may take it for an alignment and have my friend take a look at it and see what his take is on it. Thanks again.

 

Do the tires look like they have any signs of abnormal wear? There are several wear issues that can result from worn struts.

Seems like the tries have a decent amount of tread left on them from the pictures, but it's hard to tell exactly.

When my struts went bad on my TL, I was hearing noise from the rear when I would go over bumps, a slight clunking noise. The car also felt bouncy/floaty on the highway. Felt like I didn't have as much control over it as I should. Coilovers made a huge difference in highway handling.

Clearly the answer here is to get coilovers and slam the Jeep.

 

I do believe the struts may not be in the best condition as some bumps you can feel the tires bouncing and losing "control" for a split second. Just don't believe that would cause the humming.

The tires seem fine to me. I will know better once I pull one off and inspect when there isn't a load on it. I can take a few a pictures of them when I get to it.

 

They standard size tires with correct air pressure?

 

I believe they are standard size tires. They have the TPMS in them and they haven't triggered any low pressure. I will have to take my reader and do it manually and compare to the computer results.

 

Reason I asked was the now ex-son in law put 265 tires (Michelin) on the daughter's Hemi grand and even with 35psi when the rear would strike a sharp raised strip in the roadway it would propel the wheels off the ground. Hard to believe with an almost 5,000 lb vehicle, but the sidewalls were so stiff, no give, so the tires "jumped" off the ground. Now has 245/65 (Bfg) and not a problem as it drives/rides as it should.