Whats That Noise From My Car Diagnosing Vibration Under Acceleration

Hi, everyone. Sue here from 1A Auto and today we have a 2011 Hyundai Sonata in the shop, and we're checking on a vibration during acceleration. Let's diagnose it.

Now we're going to road test this for the vibration when you accelerate. So car's running. I'm going to put it in drive, and I'm going to go. And let's see what speed it starts, and let's check for steering wheel shake, body shake. Obviously, the first thing I checked before I even got in the car is I grabbed my tires and checked lug nuts and made sure all my wheels were tight, because that will obviously cause a major body vibration.

Okay. So at 35, I feel it in my seat quite a bit and on acceleration. And I could feel the whole front vehicle go like that. And de-acceleration, it smooths out. And if you paid attention, I don't know if you could see it, but my steering wheel itself did not shake. So that tells me it's not a wheel. But on acceleration, I can feel the whole engine shake. So we're going to check motor mounts, and drive train, and the front end once we get back to the shop.

So I've got the car in. I'm going to check my motor mounts, because that drive train shake like that could be caused by a motor mount that's completely broken. Like missing or broken pieces, like the rubber has actually torn out. I'm not going to do it in the car driver ... in drive, because a weak motor mount or just a slightly torn one will not cause this shake. It has to be broken completely, which I'm already pretty sure it's not going to be, but you always want to give a quick visual.

So you've got the mount here by the drive belt, serpentine belt. You've got this. They would call this the front motor mount. Then you have the left side, which is the one by the radiator, which we will be able to see from down below a lot better. But I can see it from here, and I don't see any rubber sticking out, and the bolt goes through and the nut's attached.

And then you have the rear tranny mount. It's kind of hard to see. I can visually see it from here. You can take the air box off and give that a good look through. And then you would get the tranny right side engine mount, which you can see very clearly from here and it's fully intact. Now we can see underneath and we can see the motor mounts, the one on the rear and the one on the front here by the radiator. And rubber is not ripped. Steel's not ripped, there's no crack and the welding didn't come undone. So we're all set. So I want to make sure my tie rod ends, and ball joint, and wheel bearing have no play. This car being a strut loaded vehicle, it doesn't have an upper control arm.

So first thing I'm going to do is grab my tires from nine to three and I'm going to give it a slight shake. You don't want to be like crazy. You just want to be able to feel it because a inner tie rod end is not going to give you ... You're not going to feel it if you go really hard and fast. So it's just a nice little back and forth motion. I've got nothing there. I'm going to grab 12 and six. And this is a good way to check your ball joint and your wheel bearing. Now to do the ball properly, we bring it down and we also would check it with a bar on the ground. But I'm pretty sure I have no play because I don't even have any movement. I'm going to do the same thing to the other side and if that checks out okay, then I'm going to raise it up and check out my drive train.

So I'm going to check for CV axle play on the outside here. I'll grab. And that's still tight, that means that axle nut's tight. I've got no tear on the boots. So that's in place. I'm going to follow that shaft right into the transmission. Grab it. That's normal play. Just a little bit of rocking back and forth. I'm going to go over to this side. I've already checked my tie rod ends and my ball joints. So I'm going to go right to the axle up here. Do the same thing. No tears. That's good. No signs of grease anywhere. Follow the shaft up and there's the problem. You can see how the axle has popped out of the transmission, the transaxle case. So that tells me that more than likely the clip that locks that CV shaft in on that son gear, the clip let go and broke. I can't get any wobbling out of it, but boy, when you drive this you could actually see. You could feel the shake through the whole body.

So now we know what the problem is. When we take that axle out, we'll find out if the clip is still there, or if it's inside the transmission. So now that we've pulled the axle, we can see that the clip is still attached, thank goodness. And it's just worn out. You know, it let go. So that means good news. The clip is not inside the transmission. So now I just want to recap our vibration during acceleration diagnostic.

We checked it out, confirmed it. On acceleration, major vibration. Brought it in, set it up. Went for the drive train axles after we did a quick check over the front end and we did find that the right side CV shaft had pulled itself out of the transmission. Once we removed that, we found the clip was just worn and not broken off. That was a sweet deal. No transmission problem. So I purchased a new CV shaft from 1aauto.com. Installed it. Vibration's gone.