Front diff bearing failure ??

[imq707s]

I've got a 97' Mountaineer (5.0 V8, AWD, 140,000 miles).

Over the last several months I've noticed a grinding noise at speeds around 10-30 mph. At first it was barely noticable, but now I hear it all the time. I jacked the truck up on all four corners and had a friend hop in the seat and run it up to around 20mph where the noise was very noticabe. I got under the front and I can tell it's coming from the front differential. It sounds like the pinion bearing is going bad.

Is this a common problem? What should I expect to pay for a shop to drop the front diff and repair the bad bearing(s) ?

I guess I could pull the diff out myself, it looks like it's only atached at 4 points. It this something I could do myself?

Thanks

 

[ExplorerDMB]

You may be shocked, but I looked up the time in Alldata and it said about 7 hours to pull the axle and do the bearings/gears. Now, you may be able to get someone to do it in 5; but before you go too far into getting that checked out; see if your pinion seal is leaking. If it is, pull out your fill plug and check to see how much fluid is still in there. If there isn't much, you can possibly try and fill it and see if te noise goes away. If it doesn't, your bearings are shot. I do NOT recommend pull the axle yourself and doing bearings because they can be VERY hard and you will need special tools (dial indicator, pinion preload, etc.). If it's just a pinion bearing, then you may be able to get away with under 2 hours labor wise. Good luck.

-Drew

 

[imq707s]

Thanks for the info.

As far as I can tell, the gears are just fine.....it's just the pinnion bearing making the noise.

Someone correct me if I'm wrong.....but I think I should be able to pull the gears out...replace the bearings...and put the gears back in using the same shims and I should not have to "set up" the gears. If I only change the bearings.....nothing should change that would affect the contact patch on the gear teeth.

Is this correct?

Thanks

 

[ExplorerDMB]

I would not chance that. Bearings aren't all manufactured the same. I mean even if it's a thousands of an inch differences, it'll play a difference in the gear pattern and such. I mean you could do it possibly without any problem, but you just don't know. I mean shims are as low at 5 and 10 thousands; and are not easy to set up. I've done the rear-end on mine, a older chevy rear end, another 8.8, and a mustang -- i still have a little trouble with them sometimes. But anyway, change the pinion bearing, check the fluid and change the pinion seal and see what happens. Hopefully it'll clear it up.

-Drew

 

[imq707s]

Do I have to pull all of the gears out to change just the pinion bearing?

 

[IZwack]

Someone correct me if I'm wrong.....but I think I should be able to pull the gears out...replace the bearings...and put the gears back in using the same shims and I should not have to "set up" the gears. If I only change the bearings.....nothing should change that would affect the contact patch on the gear teeth.

Is this correct?

that is correct - the same way rear pinion bearings are replaced.. just mark everything so u can put all the pieces back exactly where they came from and in the same orientation (shims, bearing caps, etc...)

Do I have to pull all of the gears out to change just the pinion bearing?

yeah, usually the carrier (with the ring gear bolted to it still) comes out and then the pinion gear.. there are actually two pinion bearings.. one will be left at the very back of the front differential and the other one will probably slide out with the pinion gear (as it is usually pressed into the pinion gear's shaft)... while the bearings are out, inspect the races- look for any grooves or pits.

 

[smiley1]

I would suspect its your front drive shaft. I had mine go a while back. The dealer opened up the Transfer case and found nothing. Then they rebuilt my front and rear diff. Still didnt solve the problem. Finally figured out it was the front drive shaft. Gota love that extended warranty!

You can check it by getting under your X. Grab the shaft with both hands and shake. If there is play then its done.

Good luck.

 

[imq707s]

I already replaced the front driveshaft a few months ago...that didn't fix it

 

[smiley1]

I already replaced the front driveshaft a few months ago...that didn't fix it

Thats Poo

 

[IZwack]

disconnect the front driveshaft and check for play at the differential input

 

[jar2187]

IMq707 not to get off topic but when you had all four tires off the ground, did all for spin at the same time, or did just the back move?

 

[IZwack]

IMq707 not to get off topic but when you had all four tires off the ground, did all for spin at the same time, or did just the back move?

if the front tires didnt spin, then the "ABS" light (possibly even the "4HI" and "4LO" lights too) should have came on or started blinking cauz basically this is the same as not recieving the proper voltage from the front ABS sensors.

It sounds like the pinion bearing is going bad.

yeayeah!

 

[EliteMotorsport]

Hey guys I am a newbie with a similar problem. My '97 Mounty V8 AWD has 109K miles on it. I get a vibration and grinding noise at 60mph or above. At those speeds if I accelerate more the noise increases some. Currently the the truck is at the tranny shop and there was some fluid leaking from the front diff., but no spots in the driveway. My mechanic said he would check the level of the fluid. I have only had the truck for 2 weeks. I was aware of some problems the AWD system can have with these model years before purchasing, but no real idea until I found this forum. I always perform maintenance immediately when I buy a used car. So I have already changed front and rear shocks, lower ball joints, camber kit, and new tires. The ride improved dramatically. Should I just go ahead and change the pinion bearing and seal while it is in the shop or just wait to see if the new gear oil will eliminate the problem?

 

[CougarX]

Instead of rebuilding the front axle (the only right way to do it) why not just pick up a used one off of Ebay or from a junkyard? They are easy to find and fairly common. Anything from a 98 up Ranger, 95-01 Explorer, or 01-05 Sport Trac will work as long as the gear ratio is the same. I had to get one for my Sport Trac a couple months ago and it cost me about $250 shipped for a 35k mile axle. I could have got one for probably $100 or so less but I needed it ASAP and had to use Buy It Now. This would be a whole lot cheaper then rebuilding yours, even if you pay someone to install it. If you are decent with tools you could do it yourself easy.

 

[smiley1]

Hey guys I am a newbie with a similar problem. My '97 Mounty V8 AWD has 109K miles on it. I get a vibration and grinding noise at 60mph or above. At those speeds if I accelerate more the noise increases some. Currently the the truck is at the tranny shop and there was some fluid leaking from the front diff., but no spots in the driveway. My mechanic said he would check the level of the fluid. I have only had the truck for 2 weeks. I was aware of some problems the AWD system can have with these model years before purchasing, but no real idea until I found this forum. I always perform maintenance immediately when I buy a used car. So I have already changed front and rear shocks, lower ball joints, camber kit, and new tires. The ride improved dramatically. Should I just go ahead and change the pinion bearing and seal while it is in the shop or just wait to see if the new gear oil will eliminate the problem?

That front drive shaft will fail before your diff and its easier to replace.

 

[jcv400ex]

When you guys are talking about the front driveshaft going, do you mean the U Joints? I have a simular noise in my 95 sport and my ABS light is on. I pulled both front hubs and the bearings are good and tight. The left one sounds "gritty" when you spin it, but has no play. Is there a way to get some grease in the bearing without ruining it?