Hi
My wife's 2014 1500 was just at the dealer for a couple of new manifolds - another topic. While their they must have checked the differential - they found that the fluid was burning/burnt and recommended that it be changed. Its at 122,000 KM now and I was planning on doing this at the recommended 192,000 KM but I'm glad they caught it.
They said that it burnt because I leave it in 4WD auto. I have done this off and on - always in the winter. I didn't know this wasn't recommended. I was trying to ensure that if my wife needs 4WD it will be their automatically.
Do you leave yours in 4WD auto for any length of time?
The dealer suggests putting it in 4WD only if there is a chance that it will be "slippery". We live in Alberta - there is a chance of it being "slippery" almost every day of the year.
If I wanted to continue to leave it in 4WD - at least for the winter - would changing the transfer case oil more frequently help to prevent damage? If so how frequent?
Thanks for the help.
What does the dealer think is causing all this heat? In 4WD auto the front differential disconnect locks up, the ring and pinion turn all the time. The ring carrier and pinion are both mounted in bearings, so the carrier and pinion are running free they are not under load except on the rare occasion when 4X4 auto actually applies torque to the front driveline. If the bearings are not bad or the gear set is not set up wrong to the point of making funny sounds the differential should not heat to the point the oil is burnt smelling.
Plenty of 4X4s, for example Jeep WJs and JKs do not have front disconnects so the front diff turns all the time, not to mention the rear differential always turns and is always under load so turning continuously is not a problem for a differential.
For what it's worth my opinion...I have had 4X4s with some type of electric or vacuum front axle disconnect, when it is disconnected if working properly only the left axle shaft and spiders and side gears spin. I have also had vehicles like Jeep WJ and JK that do not have disconnect so the ring and pinion always turn. From personal observation the lube front lube gets black quicker in a differential with disconnect than a front diff that continuously turns the ring and pinion.
I believe the reason for this is the small diameter side gears and pinion gears do not have friction reducing bearings, without bearings they created localized rather high heat on the lube that over time makes it look dirty and smell.
Another possible worth mention is when an assembly person sets up a differential gear set sometimes the preload on the pinion bearings is above what it should be, in a worse case the pinion bearing burn up, in a less severe case the bearing run hot until they wear in and develop some running clearance, this can cause the original oil to smell burnt.