Clunking when shifting – 2001 Jeep Cherokee

ANSWER : Hello James, there are a several things that can cause the symptoms you first describe. A few things I would examine are the fluid level of the transfer case and transmission, and any of the driveline joints. Low fluid level in the transmission or transfer case can cause the whirring and whining sounds to come from the transmission from a lack of lubrication. The momentary vibration you describe can be caused by play or looseness in any of the driveline joints or bushings, such as the U-joints. Both of those symptoms can also be caused by problems with the teeth or gears inside of the transmission and transfer case, so I would first check to see that those things are okay, and then move from there.

The second set of symptoms you describe can also be caused by driveline issues, however brake and suspension issues can also produce similar symptoms. Any sort of wear or play with any of the driveline shafts, either at the U-joints or mounting bushings, can cause a clunk to occur when movement through the driveline first occurs, such as when taking off from a stop. This can also be caused by severely worn brakes or suspension bushings, as well as problems with the transmission.

If all the driveline joints and bushings appear to in proper condition, I would then recommend having the vehicle inspected by a professional technician as these sorts of symptoms can sometimes be difficult to diagnose due to the complexity of modern automatic transmissions. A certified mobile mechanic from YourMechanic can provide this inspection at your home or office.

ANSWER : Hello – I would first check the battery cables and ground straps for corrosion, or other poor-connectivity problems. A strong battery can be hampered by poor connections, which will sometimes finally pass current. A failing starter solenoid (burned contacts) will act in a similar fashion. You may find that adding a jumper battery will improve the situation – at least temporarily. A failing ignition switch or starter relay can also cause start-up problems. I recommend a hard starting inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.

ANSWER : If you have all the drive shafts in the front and rear, then you will damage the transfer case or one of the axles if you drive the vehicle and engage the front end. The two different gear ratios will do this. As far as the transmission goes, you have a problem with the governor inside the transmission and may have bad second gear parts. Have a mechanic pressure test the transmission and diagnose the shifting issue for you.

ANSWER : Hello, thank you for writing in. Walking through the diagnostic process, we can rule out the wheels and suspension as a cause for the humming, as it happens as long as the car is running. The next step is attempting to replicate or control the noise through various tests, while keeping in mind we are trying to locate it. Listen for the noise with the vehicle in the "On" position to see if it is a radio circuit or speaker related problem, and to limit the amount of engine noise interfering with locating it. If messing with the radio and speaker controls has no effect on the noise, check the electronics below the driver’s controls on the dash board. There are several modules, solenoids, and other electrical devises located next to where your knees would sit while driving. For more help tracing down and resolving the noise, contact our service department to schedule an appointment.

ANSWER : If you hear a clunking noise coming from the back when you hit the brakes, the first thing you want to check is the wheels and brakes. You want to see if the brake pads are worn, if they are moving back and forth too much. Sometimes on those Jeeps, caliper bolts get loose and they make a clunk when you hit the brakes. But another thing is–the rear ends on those things are hung on bolt springs and rubber bushings. Sometimes the rubber bushing on the top of the differential will get worn. When you hit the brakes hard, you’ll hear the clunking noise as it moved back and forth. So, you’ll want to check the rubber bushings that are back there too and make sure that they don’t have any problems. If you want a more definitive answer, I would have a certified mechanic take a look of your car in person so that they can listen to the sound and diagnose you car’s noise.

ANSWER : When the engine will not start then you will need to verify if you are losing fuel pressure or losing ignition spark. You may have a bad fuel pump or crankshaft sensor. Have the computer scanned to see if you have stored codes and if there are codes for the crankshaft sensor and replace it and see if it corrects the condition.

ANSWER : The "clunk" indicates there is a loose coupling somewhere is the driveline. As you diagnosed, u-joints and the differential are the most likely fault points, but this could also be harsh engagement of the transmission due to worn clutches, clutch servo pistons, or high internal pressure within the transmission.

If the entire driveshaft was replaced, it is possible that the new driveshaft is not properly balanced. The fact that it vibrates at about 30, then again at twice that speed (that kind of vibration is called a harmonic vibration, which repeats at multiples of the first occurring speed), indicates an imbalance problem. It is also possible that the output shaft bushing on the transmission is worn severely, allowing the driveshaft to wobble from even the slightest imbalance.

To avoid any unnecessary repairs, I would recommend having you car’s shifting issue inspected by a mobile, professional mechanic, such as one from YourMechanic, to diagnose this problem, get an accurate assessment of damage and cost estimate for repairs.

ANSWER : Hi, thanks for writing in. The first thing I recommend is to make sure the ATF (automatic transmission fluid) is full.

Does the transmission shift up a gear or two and stay in that gear, or does it drive fine for a bit, then stop shifting until you turn the car off or sit still with the motor running? Or, do you continue to drive and eventually it begins shifting again. Are there any codes?

What I would do if I were diagnosing your truck would be to connect a scanner and study the data while driving to know what is going on. Without said data and not quite being clear about what is happening, it comes down to solenoids or sensors that the TCM (transmission control module) uses to calculated shift points based on load values determined by the PCM (powertrain control module).

I’m afraid all I can offer you at this point is suggesting you make sure the fluid is full and clean. If it isn’t clean, begin by replacing the filter in the pan and do a transmission fluid exchange, not just pan drop with a drain and fill. This doesn’t get all the ATF out of the transmission, and when there are problems, it pays to be as thorough as possible.

I recommend the following inspection if you should need further assistance: Car hard to shift

Hope this helps and best of luck!