View Full Version : 4WD Transfer Case or Transmission Whine
mpsrent
11-24-2005, 02:33 PM
My 2004 Envoy has a distinctive whine that increases with speed when the vehicle is in 4WD High. As soon as you switch from 4WD to AWD, the whine goes away. It almost sounds like an electric motor noise when heard from inside the vehicle.
Does anyone else have this whine? Has anyone expereinced a transmission or transfer case problem that would create such a whine? Thanks.
geneelder
11-24-2005, 02:55 PM
I get this whine when sitting in park and switching into 4Hi also, i have never actually used it, but when i switch into it, it does make that noise. I have the electronic Autotrac transfercase.
Flawsey_Bee
11-24-2005, 03:19 PM
Did you go over 55mph when you was in 4hi because your not suppose to .Also was it wet,rainy, or snowy while you was driving in this mode ?:undecided
mpsrent
11-24-2005, 03:24 PM
Speed was less than 55. This is drving on snow covered or wet pavement. The noise starts as low as 10 mph and increases proportunately as you speed up to 40 or 50.
gallai
11-24-2005, 04:36 PM
:eek: I didn't know about this 55 limit. I occasionally drove on the highway with 4HI. (It was beginning to snow and the road was totally unpredictable.)
Did I do something wrong?
Greg
ScarabEpic22
11-24-2005, 11:04 PM
:eek: I didn't know about this 55 limit. I occasionally drove on the highway with 4HI. (It was beginning to snow and the road was totally unpredictable.)
Did I do something wrong?
Greg
Probably not, it just puts too much strain on the front axle components as they arent designed for over 55mph. I would probably try not to do it again, but if it is an emergency, then it is up to you.
Wxman
11-25-2005, 01:39 AM
I just don't think there is a 55mph limit for the 4wd. At least not on the newer vehicles. The manual doesn't mention it (in fact it even says you can switch to A4WD or 4HI at any speed).
The front axle components are all moving whether in 4WD or not. The hubs don't release like days of old. The only difference is whether the front axle/driveshaft is 'connected' at the transfer case or not. The front axle and front driveshaft are all turning regardless.
Hope this helps
Wxman
lowered envoy
11-25-2005, 02:03 AM
Sounds like either the bearing on the pressure plate inside the transfer case for the clutch is making the noise.Or possibly the front output bearing on the transfer case.I haven't seen too many problems with the front differentials but seen lots of the pressure plate and bearing problems.This isn't an easy fix.the t case would have to be removed and disassembled for the repair.Hopefully this isn 't the problem.
let me know what happens.
Chris.
mpsrent
11-25-2005, 09:56 AM
Today my SERVICE 4WD light came on, so I'm off to the dealer for service. Something is definately wrong. Once I get it repaired, I will update everyone in case this happens to someone else. Thanks for all the input.
itchyfishnv
11-25-2005, 06:23 PM
what was wrong with it? encoder motor?
mpsrent
11-28-2005, 12:13 PM
I can't get in for service until Tuesday. I'm not sure what is wrong though I suspect it is electrical. It sounded like an electric motor whine, like a solenoid or something similar. What is an encoder motor?
4HI is supposed to be used for extremely slippery conditions which means you shouldn't be going near 55 mph.
A4WD can be used all of the time.
2 HI is for conditions when you know for sure it is dry.
I generally ask myself a question when deciding which mode to use. Is the road wet (or gravel)? No means 2HI, maybe means A4WD, yes means 4HI.
ScarabEpic22
11-29-2005, 03:07 AM
I dont know if my TB manual says 55MPH, but Im pretty sure my 96 Jimmy manual said 55. I dont ever want to go over 55 in 4WD (again-stupid electrical engaging when it shouldnt) so I can save my drivetrain.
mpsrent
11-29-2005, 11:03 PM
My dealer checked the problem and had to order an encoder motor for the transfer case. The motor apparently does the switching from 2 wheel to 4 wheel drive. Making progress.
mpsrent
11-30-2005, 02:17 PM
So they put the encoder motor in but that was not the fix. They opened up the transfer case and found a broken band. More parts on order and another day to wiat until she is fixed.
mpsrent
12-05-2005, 12:06 PM
Sounds like either the bearing on the pressure plate inside the transfer case for the clutch is making the noise.Or possibly the front output bearing on the transfer case.I haven't seen too many problems with the front differentials but seen lots of the pressure plate and bearing problems.This isn't an easy fix.the t case would have to be removed and disassembled for the repair.Hopefully this isn 't the problem.
let me know what happens.
Chris.
Chris, you called it right! The bearing on the pressure plate went, taking out the entire tranfer case, Everything inside exploded. They put in a new transfer case under warranty as the cost to repair the old one was more than the cost of a new unit. Thanks for the help.
To anyone out there who hears a speed sensitive whine when operating your vehicle in 4wd, you had better get it checked because my experience is that its a sign that your transfer case may be going.
needonetime
09-30-2009, 10:00 PM
I hate to crack open an old old OLD thread but I really hope this isn't the case on my truck. I put my truck in 4wd today and noticed a whinning noise in the front passenger side. It gets louder the faster you go, and immediately starts to fade when going from 4HI to Auto.
I JUST had my TC serviced two weeks ago maybe a little longer. Here's to hoping they remembered to piece everything back together when they did it?