4wd rookie

[cavmansdad]

I just bought a 1999 explorer. I had new brakes and rotors and ball joints installed. I am not familar with how to operate a 4wd vehicle as this is our first 4wd vehicle. When is a good time to use 4w hi and 4w low? My wife use it in bad snow weather. She said when she put it in 4w hi it made a loud grinding noise. When she heard that she stopped and put it back in 2wd. Is this sound normal? Can you put it in 4wd hi or low as the vehicle is moving at any speed?

[denisb]

My owners manual (04 Sport Trac) has no speed limit to engage 4 Hi in. Personally, I'm not a big fan of engaging 4x4 at highway speeds, but I guess that's just me. Besides, usually you know the weather before you get on the highway and if you need the 4x4 on the highway you should slow down.

4Hi should be used on slippery roads or dirt not dry pavement. You should be able to engage as long as wheels aren't spinning. By spinning I mean stuck in 2wd and the rear wheels spinning while engaging. If you engage only once stuck, try slowly going forward and/or reverse until you feel your 4x4 engaging otherwise you might be hearing loud clucks or grinding.

4 Low- need to be stopped, brakes on and in neutral. Should only be used when torque is needed or extremely low traction (Sand, Mud etc) and speeds are slow (crawling like speeds).

You will hear a roar when in 4x4, similar to a bad bearing if you've ever heard one. Turning sharply will make the vehicle feel like it's "binding up" (almost like the brakes are applied) in any 4x4 mode. Some clunks might also be heard while turning sharply or going over bigger bumps but excessive clucking should be looked into.

Hope this helps,

Denis

[cavmansdad]

is it a one time glunk noise once engaged in 4wd?

[denisb]

Originally Posted by cavmansdad

is it a one time glunk noise once engaged in 4wd?

Typicaly, you should only hear a clunck when engaging or when dissengaging (might be so minimal you won't even hear it). Dissengaging might only be heard after some time after.

The hubs will typically stay engaged until pressure or torque is removed from the shafts, so if you dissengage on the move, there might still be enough torque on the front CV shafts to actually hold the hubs engaged. I've seen having to back a few feet (this changes direction of the hub rotation) to help them dissengage.

If you notice after dissengaging that you're still getting a Hum or roar, stop and back up a few feet and this will probably solve your problem.

[autoguy25]

Usually you want to have the vehicle stopped and in neutral before you try to engage the 4wd

[denisb]

Originally Posted by autoguy25

Usually you want to have the vehicle stopped and in neutral before you try to engage the 4wd

4 lo yes. 4Hi can be engaged on the fly.