A question about spontaneous combustion, and problems with a motor mount installation

December 1, 2017 | By Staff


A friend’s wife was in my garage the other day and complained to me that oily paper towels, newspaper and shop rags can combust spontaneously if left in a trashcan or a pile, as I have done on occasion. The possibility always seemed so remote that I never worried about it. Am I being foolhardy?

Also, I was changing out the motor mounts on my car the other day and ran into a little difficulty. The passenger side was pretty easy. I merely removed fasteners, jacked up the engine an inch with a 2x8x12 on a floor jack so as not to damage the pan. Then all I did was slide in the new mount, and add fasteners.

The driver side was not nearly as much fun. I removed fasteners, jacked up the engine and lifted the front wheels off the floor, but there still wasn’t enough clearance to remove the mount. Removing the stamped sub-mount seems like a no-brainer, but the nicely accessible bolts have freespinning nuts on the bottom and the transverse front spring is in the way.

The question is, why doesn’t the engine rise as high as it did for the other side? The only differences seem to be clutch linkage, which is under no stress, plus a flimsy little sheet metal splash shield, which looks like it would crumple with any pressure.


Concerning oily rags the answer is yes, you are being foolhardy. Your friend’s wife is right. A retired fire captain buddy of mine says that spontaneous combustion of oily rags was one of the things they demonstrated in his training classes. He also admonished me to get a fire extinguisher and smoke and carbon monoxide alarms for my shop. I complied because he knows what he’s talking about and I also wanted to put an end to his lectures.

As for your motor mounts, engines can move around quite a bit even on good mounts, and bad ones will allow the motor to bounce around considerably while going over bumps and when giving it the gas, because the engine’s torque will force it to rotate out of alignment.

When you jacked the engine up, did you lift it only at the front, in which case it would be at an ever-increasing angle? Also, the new mount on the passenger side probably held the engine more securely than the old one on the driver side would have done.

My advice is to only raise the engine far enough to slide in the mounts and then use a big screwdriver or long extension to align the holes while a friend lets the jack down slowly and you pop in the fasteners.