For Jeep owners, the only two constants in the lives of their vehicles are repair and maintenance. And even if you do the routine service and change fluids, you should still be ready for anything.
Luckily, there are many signs to watch out for, and one of the most common signs is the noise coming from the vehicle. Jeeps produce lots of noises, but some uncommon noises like a knocking sound should warn you of impending problems.
So does your Jeep produce a loud knocking sound when taking off? Does it produce a clunking metal noise when passing through a bump? Does the knocking noise start as soon as you press the gas pedal? These are issues that many Jeep owners have to deal with.
If you want to know how to troubleshoot Jeep knocking noise when accelerating, please read on…
What Are the Symptoms to Watch Out For?
Before going through the signs of a mechanical issue, you need to understand that Jeeps tend to produce noises. Therefore before assuming the worst, you must eliminate a few possibilities. If you have been off-roading recently, and your Jeep starts making noises, then you should look at the skid plate. You may have knocked the skid plate resulting in the exhaust bumping into it when accelerating.
Another minor issue that can cause the noises is a loose control arm bushing. This is common among Jeeps with stock lower control arms. If you were off-roading, then confirm all the exhaust clamps are still intact and correctly torqued. If all the above are okay, you should focus on the type of noise and where they are coming from. Some of the signs of a serious problem include:
- Excessive play
- Loose metallic noises coming from the rear part of the Jeep
- Loud clunking sounds when taking off and when accelerating
Causes of Jeep Knocking Noise When Accelerating
Cracked Engine Mount
Engine mounts are vibration dampeners that protect the engine bay from the vibrating engine. But when the engine mounts crack, you will hear lots of noises coming from the engine bay when accelerating.
Some of the sounds produced include knocking, rattling, or clunking. When you hear these sounds, you should know that the engine is loose. So make sure you replace the engine mounts as soon as possible. Driving with a loose engine can be very unsafe for everyone on the road.
How to Replace Damaged Engine Mount
If you need to replace the engine mounts, follow these steps:
1. Isolate the damaged mount
Start by turning on the engine and putting the Jeep’s gear to Park. Next, move around the engine with a flashlight and locate all the engine mounts. After locating them, you can look for the one producing more vibrations. The one producing excessive movement is normally broken. Finally, you can switch off the engine.
2. Replace the damaged mount
Raise the Jeep using a floor jack to create more than enough space for you to access the damaged mount. Support the engine using a block of wood between the oil pan and the floor jack.
Next, remove the bolts and nuts holding the mount in place and remove it. Finally, you can install a matching engine mount, and you’re good to go.
Cracked Transmission Mounts
Engine and transmission mounts are reliable rubber components that rarely crack or break. These components are designed to serve you for a very long time. But, when exposed to hard off-road driving or an accident, the transmission mount can crack and start producing clunking noises.
The clunking sounds are caused by the engine shafts hitting each other while accelerating or braking.
Symptoms of a cracked transmission mount
1. Steering Problems
If your Jeep has issues steering around corners, then you may have a cracked transmission mount. Note that a bad transmission mount can’t hold the engine in place. Therefore, the movement of the engine will affect how your Jeep negotiates corners.
2. Moving Engine
The Jeep was designed to move its engine when running. So when you feel the engine moving all over, then the transmission mounts may be damaged. This will force the Jeep to start vibrating when in motion. A loose engine can also produce clunking noises and vibrate.
3. Damaged Parts
When the transmission mounts do not secure the engine, it may start moving and end up damaging its other components. So when you open the hood, you may notice the solid rubber part of the engine is damaged. The wiring, hoses, and transmission linkages may also be affected by the movement of the engine.
4. Excess Driveshaft Vibration
The transmission mounts support the engine driveshaft, which is an extension of the crankshaft. When the transmission mount is broken, the stability in the driveshaft will be lost. This will result in a lot of noises and vibrations. These vibrations can be extremely high when accelerating at high speeds.
How to Replace a Transmission Mount
Replacing this mount is fairly easy, so you can do it yourself or let the mechanic do it. To replace it, you should do the following:
- Raise the Jeep’s transmission using the jack. If it’s broken, the transmission will be lifted from the cross-axle.
- Remove the broken transmission mount
- Next, slide a new mount on the cross-part and lower the jack. While lowering the jack, make sure that the mount openings gaps the cross-axle and the transmission.
- Finally, you can tighten it using a customizable wrench.
A jeep wrangler has four U-joints (universal joints). One is located at the rear driveshaft, and the other is at the front driveshaft. The other two are on the Jeep’s front axle shaft. The front universal joint is linked to the front axle through the front diff (differential). On the other hand, the rear one connects to the front end of the rear shaft to the rear diff.
The work of the universal joints is to compensate for the lateral and vertical movement of the diff when accelerating. So when driving on high traction surfaces, make sure you use the 2H option with a part-time 4WD. The 2H mode always propels the rear wheels and engages the rear driveshaft.
U-joint rubber caps tend to wear out or get damaged with time. This will result in the grease draining which leaves the U-joint dry. When this happens, the U-joints will fail, resulting in excess movements in the U-joint and loud clunking sound.
The only solution to this problem is replacing the U-joint cap and adding grease to reduce friction. But if you still continue driving the car, the U-Joint may get damaged. And you may end up spending more on a new U-joint or differential.
Loose Axle Mounts
An axle mount is a rubber bush that tends to wear down with time or even crack. And when this happens, it will start producing a heavy metal clunking noise. So you may have to replace it or take it to a professional.
Related: You might also want to know what to do if your Jeep Wrangler won’t start but has power. Or, learn how to deal with leaks in Wrangler.
Jeeps are designed for tackling tough terrains. Therefore, Jeep knocking noise when accelerating shouldn’t come as a surprise to you if you have been off-roading. The knocking noise can be caused by a cracked engine or transmission mount. In some cases, the problem may be the U-joint, so before damaging your Jeep even further, you should troubleshoot the issue and solve it.