My front differential went out on my 97 Jeep Grand Cherokee about 8 months ago. Since then Ive replaced it three times with a new front end (used). Last time it lasted one day before going out. Am I getting bad parts or is there something the mechanics are doing wrong. Hard to believe the all three were bad.

unless you have a vacuum diff locker system , the hose may be a breather hose to put the end well above water level when in deep water--possibly into the air inlet around the air filter

If that's a 4 wheel drive make sure the front gear ratio matches the rear ratio or you'll destroy the gears everytime. I had the same problem with my '97 Grand Cherokee.

Unless someone changed it, the front differential is always an "open" style. If it was not, it would make it difficult to make turns. There are kits available to install either a positraction center section or a "spool", but those are used primarily in vehicles that are used off road where sacrificing drive-ability is not an issue. The easiest way to determine if a particular unit has a posi is to lift both wheels off the ground and turn one side. If the opposite wheel turns in the same direction it is a posi. If it fails to turn or turns in the opposite direction it is an open unit.

Check the front stabilizer bar and the bushings on it. It is located under the radiator with arms that bend back to each front tire.

Pull the alternator brackets and front engine brackets off until you get to the water pump. You will also need to remove the fan shroud and then the fan. Remove the water pump and then you will see an aluminum cover and that will be your timing cover. remove the cover and clean all the gasket off the engine and the cover. use a razor blade, and make sure there in no oil or grease on the parts where the gasket lies. Put your gasket on, bolt the cover back on with the new gasket and repeat the teardown process in reverse.

i had a similar problem with a gmc jimmy and changed ignition module several times before i ended up buying a new distributor and changing it out and have had no problem since 2 years ago

if you don't have experience with working on cars .... i recommend you take it to a mechanic you trust to assess what kind of work it would need. it's a small investment compared to buying someone elses problem

The 99 Jeep Grand Cherokee was prone to bad diff bearings because they changed the plant where they were made. The new plant used inferior materials. The only way to fix it is to replace and set the diff clearences.

check the differential fluid in the rear differential. if the fluid is low, add fluid and see if the noise is still there, if the fluid level is ok see if the fluid appears metallic, if it is metallic looking or excessively thick it would be a good idea to have the bearings checked out. i am in the process of rebuilding a front differential on a 98 jeep grand cherokee for the same problem. the bearings inside the differential on the carrier and pinion gear were worn out causing a humming noise. if the wear is excessive the gears might also need to be replaced

call jeep and give them last 9 digits of your vin and ask for three things -Differential Type,Gear ratio, and Track lock- They will give you
1) Dana 35 or 44
2) Gear Ratio 3.31 or 3.73
3) Track Lock - yes/no