4wd grinding, popping and vibration....

[jtillery]

I searched the forums to try to find a similar problem but have been unable to. I have a 95 Explorer Sport with 131,000 miles with automatic tranny. The 4WD worked great up until this year. The problem I have is whenever the 4wd engages it makes a grinding noise, pops occassionally and has some vibration. As soon as it kicks out it is quiet and normally rides smooth right away. (sometimes it takes a minute or so for the vibration to stop). This happens with it in 4WD high (which is automatic). I haven't tried it in 4LO. One thing I have noticed recently, is between 5-30MPH it makes a chirping noise, it seems to come from the passenger side front. Not sure if it is related or not. Any ideas on what might be wrong?

Thanks

 

[hardtack]

Hi j
I don't have a definite answer for you, but I'm having similar noises when using 4H range.
I believe its the automatic locking hubs not completely engaging. In my case the temperature has dropped near 0 degrees and I think the grease in the hubs is too stiff to let them work correctly, so I plan to clean them out and use a heavy weight oil instead of grease.
I don't know about your chirping noise, maybe someone else can help both of us with some answers.

 

[MrShorty]

The trouble with answering both your questions at once is that you have different 4WD systems.

hardtack: the auto hubs are designed to be a "dry" hub, which means there shouldn't be any grease in them. If your hubs are full of grease, that could be causing problems, and cleaning the grease out does indeed represent a good first thing to try. Most people recommend ATF to clean the grease out of the hubs and to lube them instead of a heavy gear oil. Probably doesn't matter as long as you get all that grease out.

jtillery: grinding, popping, vibration -- have you checked the CV joints in the front axleshafts? u-joints in the front driveshaft? Any sign of vacuum leaks to the front differential (front end engaging/disengaging randomly).
The control trac system, with it's clutches, can be more sensitive to the condition of the transfer case fluid. You might try draining and refilling the transfer case to see if that helps (be sure to pull the fill plug out before the drain plug. don't want to get it drained and then realize you can't get the fill plug off to fill).
I've also seen chirping noises from all kinds of loose components. If the chirp isn't related to the 4WD, you may just have to go through the suspension until you find the loose component.