Have you tried engaging 4-wheel drive 4H on your Wrangler, only to hear a loud grinding noise coming from the front of the vehicle? Does it sound like a metal-on-metal winding-up sound? Does it engage and then slip out of 4H after driving a few hundred feet?
If your Jeep Wrangler grinds after engaging 4WD then you need to investigate the following components:
- Linkages
- Low transfer case oil
- Body lifts
- U-joint
There’s nothing worse than a metal-on-metal grinding noise, especially when it’s coming from your vehicle.
If trying to engage 4WD is hard and you need to use excessive force to engage 4H then you might want to read the rest of this article.
Let’s start by identifying the symptoms first.
Table of Contents
Wrangler 4-Wheel Drive Grinding
Identifying the exact symptoms will allow us to eliminate other irrelevant possibilities and isolate the exact problem. So let’s get stuck in.
Symptoms
- intermittent grinding noise from the front center of the vehicle when engaging 4WD
- Grinding when turning until 4H is disengaged and 2H is selected
- Metal-on-Metal noises in 4H and 4L
- Grinding sensations in the transmission shifter
- 4WD engages for a short period then pops out
So we’ve established the symptoms, let’s now investigate why
Not Engaging Fully (Linkages)
4WD not engaging and grinding on the Jeep Wrangler is actually a common occurrence. It’s more common if you often engage in 4H and often go wheeling. Truth is, the factory linkages are prone to working themselves loose or breaking completely. The TJ Wranglers 4WD operating ranges are selected with a floor-mounted shift lever. The shift lever is connected to the transfer case range lever by an adjustable linkage rod.
The short low-range gear selector requires a nice firm yank to get it into 4H properly. The newer, more modern Wranglers make use of a dial function that operates an electric motor to engage 4WD.
If the linkage has just worked itself loose, this can be caused by old age or regularly traveling on corrugated roads. It’s a relatively simple procedure to adjust the linkage and all you’ll need to do is, adjust the set screw, and you’ll be good to go. No special tools or expertise is required. If this happens often or reoccurs soon, you might want to consider upgrading the factory linkages to a cable shift option instead.
If the linkage has just worked itself loose, this can be caused by old age or regularly traveling on corrugated roads.
Linkage Adjustment process
You will need an assistant to carry this simple 5-step inspection.
| Step 1 | Get underneath your wrangler |
| Step 2 | Locate the linkage on the transfer case |
| Step 3 | Keep a close eye on the linkage while you signal to your assistant |
| Step 4 | Instruct your assistant to engage 4H while you observe the linkage movement |
| Step 5 | Determine if the linkage needs adjustment or replacement |
So, the reason why the transmission slips out of 4H is that the linkage isn’t fully engaged and 4WD isn’t engaged properly in the transfer case. If you’re experiencing difficulty engaging 4H it also explains why you will struggle to engage 4Lo. You can read more about that here: 4WD grinding when turning.
If you are out on the trails and desperately need to engage 4WD then there is a quick DIY method you can try.
DIY FIX:
All you need to manually engage 4WD is a screwdriver. A nice long one works well. Just put it in with a little prying. You will have it engaging from there on out. You can spray some lithium grease on the pivot points to allow the linkages to function better and engage more easily.
Transfer Case
Another reason for difficult shifting and grinding in 4WD is low oil levels in your transfer case. Dirty transfer case oil is also a reason. If your TC oil is low or dirty it can cause your shifter to disengage and emit loud grinding noises while driving. As the TC oil loses its efficacy and lubrication through old age and breakdown, it causes friction and metal filings inside the transfer case. A low oil level is generally the result of a leak, inadequate lubricant fill, or incorrect lubricant level check.
When shifting into 4WD if the rear wheels are rotating it will grind and or bang, when it engages. This is bad news since you could potentially break teeth off internal gears inside the transfer case. Engaging 4-wheel drive while driving essentially locks the front and rear driveshaft’s together while one is spinning at a few thousand RPM’s and the other is stationary. In this instance, one of two things happen. By some freak occurrence, the splines mesh and everything starts turning together. That is when you hear a bang.
Alternatively, the splines attempt to mesh together and do not succeed. When the splines fail to mesh you hear a grinding noise. If the front wheels are rotating at a similar speed, or close enough as the rear wheels, then the splines mesh seamlessly and there is no bang or grinding noise.
https://4wheeldriveguide.com/4-wheel-drive-grinding-when-turning/
It would be a good exercise to do an oil analysis on the TC to check for metal particles. Open the front diff and inspect spider gears for damage.
Diagnosis and testing of the Transfer Case
| Condition | Cause | Action |
| Transfer case difficult to shift or will not shift into the desired range | 1) Vehicle speed too great to permit shifting. 2) If the vehicle was operated for an extended period in 4H mode on a dry surface, the driveline torque load may cause difficulty. 3) Transfer case shift linkage binding. 4) Insufficient or incorrect lubricant. 5) Internal transfer case components binding, worn or damaged. | 1) Slow the vehicle and shift into the desired range. 2) Stop the vehicle and shift the transfer case to a Neutral position. The transfer case can then be shifted to the desired mode. 3) Repair or replace linkage as necessary. 4) Drain and refill the transfer case with the correct type and quantity of lubricant. 5) Repair or replace components as necessary. |
| Transfer case noisy in all drive modes. | 1) Insufficient or incorrect lubricant | 1) Drain and refill the transfer case with the correct type and quantity of lubricant. |
| Transfer case noisy while in, or jumps out of, 4L mode. | 1) Transfer case not completely engaged in 4L position. 2) Transfer case shift linkage out of adjustment. 3) Transfer case shift linkage loss or binding. 4) Range fork damaged, inserts worn, or fork is binding on the shift rail. 5) low range gear is worn or damaged. | 1) Slow the vehicle, shift the transfer case to the Neutral position, and then shift into the 4L model. 2) Adjust linkage as necessary. 3) Repair, replace, or tighten linkage components as necessary. 4) Repair or replace components as necessary. 5) Repair or replace components as necessary. |
| Lubricant leaking from transfer case seals or vent. | 1) Transfer case overfilled. 2) Transfer case vent closed or restricted. 3) Transfer case seals damaged or installed incorrectly. | 1) Drain lubricant to the correct level. 2) Clean or replace the vent as necessary. 3) Replace suspect seal. |
| Abnormal tire wear | 1) Extended operation in 4H mode on dry surfaces, | 1) Operate vehicle in 2H mode on dry surfaces |
Body Lift
If you have recently installed a body lift on your Wrangler, it could result in your 4WD linkage being too short and not engaging fully, and cause it to slip out of 4WD mode.
The Body Lift kit usually includes a T-case shifter relocation bracket that “drops” the pivot point for the shifter down, which solves this problem. To solve the Manual Transmission problem, you may need to trim the boot frame and relocate the console back a bit.
U-joint
Most likely not the problem in this instance, however, it’s worth a look if you are hearing grinding coming from the front of your Jeep only in 4WD. This is because when you are driving in 2H on dry pavement or highway you don’t engage the front driveshaft. Might be a good idea to inspect your front CV joints as well.
Resources
TJ Transfer Case Shift Linkages
Transmission Shift Cable Bushing Repair Kit
Conclusion
There are a few possible causes of the grinding noise when 4-wheel drive is engaged as well as when attempting to shift into 4-wheel drive from 2H mode. In most cases it is the linkages, however, never assume anything and if you are not mechanically minded, rather take your Jeep to a trustworthy mechanic to do the necessary inspections. A broken or loose linkage is not a serious problem. A dry transfer case on the other hand can result in serious damage and a huge repair bill if left unattended.