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I had visually checked it from the bottom several weeks ago, and it looked okay. But after reading about even more failures recently, and given that I'm going to the track next weekend, I decided to physically check my motor mount bolt.
I put the front on ramps and removed the battery and box. I got underneath and removed the undertray, but couldn't locate the bottom of the bolt (or so I thought). Then I put the jack under the transaxle and jacked up a bit until the car started to lift. I didn't see the head of the bolt pop up, so I thought it was tight. Then I turned the bolt counterclockwise, carefully noting the amount of torque required to break the bolt loose. It was maybe 30 ft-lbs! I gave it a couple of turns and noticed that the head of the bolt was not moving up, which it should have been. I pumped the jack handle two more times, and the bolt jumped up quite a bit, more than what I thought I had loosened it. So I tightened the bolt back down, and it definitely took more turns to get it tight than what I had turned it loosening it. [If it isn' clear, what this means is that, unfortunately, I don't have visual proof that the bolt was loose, though I am convinced that it was.] I got back under the car and realized that it wasn't that I couldn't locate the bottom of the bolt earlier, I just didn't recognize it because it wasn't sticking out as far as it was when I visually checked it several weeks ago.
I then removed the bolt completely and looked at everything. The bolt did not have loctite on it, and there were some small bits of loose metal in the threads. I looked in the hole and saw that the threaded hole in the transaxle was not centered with the hole in the mount itself. It was as far off toward the front as it could go, probably due to the angle of the car and the jack. In the metal sleeve in the mount (this piece is unthreaded) I saw marks corresponding to the threads of the bolt when I loosened it. This binding between the bolt and the sleeve could have been the only reason I felt any breakout torque at all. The threads in the aluminum piece below looked to be in reasonable shape (can't see much down there). The threaded hole is about an inch long, which should be plenty of threads if they are all engaged.
I cleaned the bolt, put some red loctite on it, and tightened it to 75 ft-lbs.
The car has about 3200 miles on it. I bought it Nov. 10, but it had been on the lot for a couple of weeks before then (where do I find the build date again?) Most of the time, this car is driven fairly easily.
There is something else. As long as I've had the car, there has been a low thunk over bumps. It sounded like it was radiating from a large piece of sheet metal with some weight to it. Imagine being inside the car and someone pounds the side of their fist on the hood. It wasn't a sound that a car should make. It was easiest to hear when going over a speed hump (hump, not bump). The sound was made just when the front wheels transitioned back from the hump to the road. This is what prompted me to visually check my motor mount a while back. In a way, I wanted to find something loose so I could have a fix for the thunk, but it appeared to be tight. On the way home tonight, I didn't hear the thunk during the entire trip. I'll need to drive on more familiar roads for a bit to really know.
Go check your motor mount, or take it to the dealer PRONTO!
I put the front on ramps and removed the battery and box. I got underneath and removed the undertray, but couldn't locate the bottom of the bolt (or so I thought). Then I put the jack under the transaxle and jacked up a bit until the car started to lift. I didn't see the head of the bolt pop up, so I thought it was tight. Then I turned the bolt counterclockwise, carefully noting the amount of torque required to break the bolt loose. It was maybe 30 ft-lbs! I gave it a couple of turns and noticed that the head of the bolt was not moving up, which it should have been. I pumped the jack handle two more times, and the bolt jumped up quite a bit, more than what I thought I had loosened it. So I tightened the bolt back down, and it definitely took more turns to get it tight than what I had turned it loosening it. [If it isn' clear, what this means is that, unfortunately, I don't have visual proof that the bolt was loose, though I am convinced that it was.] I got back under the car and realized that it wasn't that I couldn't locate the bottom of the bolt earlier, I just didn't recognize it because it wasn't sticking out as far as it was when I visually checked it several weeks ago.
I then removed the bolt completely and looked at everything. The bolt did not have loctite on it, and there were some small bits of loose metal in the threads. I looked in the hole and saw that the threaded hole in the transaxle was not centered with the hole in the mount itself. It was as far off toward the front as it could go, probably due to the angle of the car and the jack. In the metal sleeve in the mount (this piece is unthreaded) I saw marks corresponding to the threads of the bolt when I loosened it. This binding between the bolt and the sleeve could have been the only reason I felt any breakout torque at all. The threads in the aluminum piece below looked to be in reasonable shape (can't see much down there). The threaded hole is about an inch long, which should be plenty of threads if they are all engaged.
I cleaned the bolt, put some red loctite on it, and tightened it to 75 ft-lbs.
The car has about 3200 miles on it. I bought it Nov. 10, but it had been on the lot for a couple of weeks before then (where do I find the build date again?) Most of the time, this car is driven fairly easily.
There is something else. As long as I've had the car, there has been a low thunk over bumps. It sounded like it was radiating from a large piece of sheet metal with some weight to it. Imagine being inside the car and someone pounds the side of their fist on the hood. It wasn't a sound that a car should make. It was easiest to hear when going over a speed hump (hump, not bump). The sound was made just when the front wheels transitioned back from the hump to the road. This is what prompted me to visually check my motor mount a while back. In a way, I wanted to find something loose so I could have a fix for the thunk, but it appeared to be tight. On the way home tonight, I didn't hear the thunk during the entire trip. I'll need to drive on more familiar roads for a bit to really know.
Go check your motor mount, or take it to the dealer PRONTO!
