4-High On Dry Roads

SCoke89 · February 4, 2019

Hey all,

New owner of a 2016 Z71 with 20,000 miles. Had a bunch of snow over the past week (have had the truck for a week) and I basically ran it in 4 high for 5 days straight. About 150 miles. I forgot to turn it off on a dryer day (was -20 out but no snow on the roads) and probably did about 25 miles of city driving. The internet is all over the place in opinions, ranging from you’re probably ok to don’t even drive a mile on dry roads. I was not aggressive, very gentle what with the cold. No fast turns. Still, I’m a bit worried I’ve fouled something up. There was never any popping or grinding, just a bit of whining in turns. I’ve since driven about 100 miles in two wheel with no issues, and just took it out in a field and threw it in 4 high. Did some tight circles both directions and heard no noise at all. Any thoughts?

Dnt · February 4, 2019

It did create some stress and your transfer case probably has a little less clutch pack life I would probably just go ahead and swap the fluid out in the transfers case to get rid on any clutch dust material and drive chain metal shavings that may have been shaved off. The transfer case holds very little fluid like less than 2 quarts of DEXRON Vl and is easy to change out if you have a transfer hand pump takes like 30 minutes in your driveway. Make sure and clean the magnetic plug. If you can post a pic of the fluid as it drains and a good pic of the drain plug magnet with debris on it. that will probably encourage a lot more people to do a early fluid change LOL

cheyenne383 · February 4, 2019

I leave mine in 4 HI most of the winter (Oct-May) and have it on wet/ice/snow/dry depending on the day. I wouldn't worry to much, it does bind when cornering in 4HI which I try to avoid but it happens... what you're describing isn't going to do any major harm.

Dnt · February 4, 2019

Cheyenne383 out on the open road I run the in the 4whl auto mode in the rain/snow/icy conditions which prevents the binding. Why would you not utilize the auto 4whl setting instead of 4whl high out on the road?

It seems like someone had told me at one time that the 3/4 ton and up trucks did not have a 4whl auto setting, does yours happen to be a 3/4 ton?

cheyenne383 · February 4, 2019

38 minutes ago, Dnt said:

Cheyenne383 out on the open road I run the in the 4whl auto mode in the rain/snow/icy conditions which prevents the binding. Why would you not utilize the auto 4whl setting instead of 4whl high out on the road?

It seems like someone had told me at one time that the 3/4 ton and up trucks did not have a 4whl auto setting, does yours happen to be a 3/4 ton?

My truck is a 2017 5.3/6L80E/2 spd t-case/3.08 and my wife drives a 2016 5.3/6L80E/1 spd t-case/3.08.

Everyone has an opinion... I have auto on my truck and my wife's burb and don't use it. I'm sure plenty of people do without issue but here's my take on it...

1. When it's in 4HI everything is already locked in place, less time to react to slippage on ice.

2 The other advantage in my opinion is when it's in AUTO the front diff is engaged and the transfer case cycles in and out as needed. I think the clutches in the transfer case will wear faster this way and need repair sooner than if I just run it in 4HI.

If conditions allow me to run more than 55 or so then it's a safe bet I can just run it in 2WD but I've had it up 70+ passing in 4HI with my 2003 Z71/2011 Silvy/current vehicles all with autotracs without issues.

Edited February 4, 2019 by cheyenne383

SCoke89 · February 4, 2019

I appreciate the input here everyone. Got my mechanic on the phone and he didn’t sound the least bit worried. Said he would take a look at all fluids involved next time I’m in just to be sure but no need to rush in and get anything done at the moment. I’ll avoid 4WD going forward until I really need it though!

Doug_Scott · February 4, 2019

If the transfer case has a clutch pack in it then there is nothing to worry about. I think most of the horror tales come from the early 4x4 transfer cases. By early I mean the 70s. That's when 4x4 became more common. Transfer cases back then wsre sensitive to how they were engaged. Customers would spend a big chunk of change for their full-time 4x4 only to return a couple of months later for a set of manual locking hubs. Anyways back to the question first thing you do is read your owners manual. That book was written by the people that engineered and built your truck if you find that some anonymous internet user has a different opinion, believe the manual first. Unless that anonymous internet user is willing to warrantee his opinion.