2002 Pathfinder Front Diff Grinding

[ADIDASilvias]

Hello Everyone!

The past few days we have had quite a bit of snow around here, so I have been driving mostly in 4hi and I noticed something odd. While braking in 4hi and sliding slightly, I have heard a grinding coming from my front differential. At one corner in particular that is downhill and a little off camber it has happened twice now. My thoughts are that the ABS is kicking in from the slip condition and for some reason the front diff is not liking what the brake system is trying to accomplish.

I think it is the front differential and not the brakes based on the location of the noise, but could be wrong. The first time it happened I thought I had a problem with my brakes, but otherwise they feel fine. This is the only condition in which the noise can be reproduced.

Any thoughts on what might be the culprit?

My 2002 Pathy has stock suspension, stock tire size, and the brakes are worn but NOT totally shot at this point.

[01silvapathy]

Jack the truck up and put jack stands under it to allow all the wheels to be off the ground and then put it in 4wd and let off the brakes and let the truck idle. Then brake and turn ect to see if you can re create the noise. If you dont have enough jack stands then chock the rear wheels jack up the front and put the truck in 4wd and neutral and turn the front tires by hand to see if you can make the noise.

[ADIDASilvias]

Nice, yeah, I guess if I could re-create the noise on the jack stands that would definitely rule out the ABS and help locate the noise.

It's weird cause the truck brakes fine in all other conditions, and it has only happened in that specific situation, i.e. slow sliding while braking.

I also have a slight hesitation in 3rd and 4th gear (possibly in others but most prominent in 3rd and 4th) during slow to medium acceleration. I do not feel the hesitation in the gas pedal, so I am almost certain it is not the engine, and 1st, 2nd, and 5th it is not present enough to notice. Maybe rear diff? or transmission (5sp manual)? It's not like the truck bucks violently from it so I am not overly concerned, but if it is an easy fix I'd like to eliminate it.

I still need to change all fluids except oil since I just purchased the vehicle about 2 months ago. I am thinking AMSOIL all around . . . Severe Gear for the diffs.

[Towncivilian]

If you go with Amsoil Severe Gear, go with 75W-110. SAE revised the weight grading a few years back and the lower viscosity range of 75W-90 is still 75W-90, while the higher half is 75W-110. I'm not sure which our differentials prefer, but it isn't that much of a viscosity difference between the two at 100C anyway; Severe Gear 75W-90 is 16.9 cSt @ 100C, while Severe Gear 75W-110 is 20.3 cSt @ 100C. Although, 75W-90 might be preferred for the winter months however as it is quite a bit thinner at 40C than the 75W-110... hmm, I just contradicted myself and now don't know which to advise for colder climates.

[ADIDASilvias]

Hmmmm . . . now you have me wondering on that too Town. I had originally planned on 75W-90 due to the lower kinematic viscosity at 40C. We do see some colder temperatures here, and since the kV difference is minimal at 100C but quite different at 40C I would think the 75W-90 would be preferred given the Colorado climate. Where I live though we can see -20 degrees Fahrenheit (rare but it happens) in the winter and 106 degrees F (happens every year) in the summer. Quite the swing.

What do you think? 75W-90 or 75W-110?

[Towncivilian]

I'd go with 75W-90 in your climate. It's pretty hard to go wrong especially when using Amsoil Severe Gear. I'd still send an email to Amsoil though, see what they recommend.