Dear Tom and Ray:
The engine on my '97 Pontiac Bonneville FELL OUT while I was driving 55 miles an hour yesterday! Luckily I am fine. Had it happened mere seconds sooner, I would have been in a lake, as my steering and brakes were rendered useless.
So, how could this happen? I heard a loud CLUNK first, and thought I ran over something ... in the rearview mirror I saw a round black thing bouncing on the road, and then quickly realized the engine had cut out, my steering was not working, and my power brakes were, er, powerless. The nice ditch stopped me.
Have you ever heard of this happening? I thought stuff like this only happened in cartoons. Then again, it would not be so inaccurate to say my life is like one big cartoon, but I'll save that for Dr. Phil. Thanks! Love your column.
RAY: Did the Check Engine light come on? Finally, a good use for that light!
TOM: I don't think the engine fell out, Robyn. But it could have fallen down.
RAY: You really can't run over the engine and see it bouncing down the road behind you. It's too massive. The car wouldn't be able to go over it. The car would have to flip over it in order to separate itself from the engine.
TOM: Here's what probably happened. The engine and transmission are held in a cradle, or sub-frame, that's bolted to the chassis of the car. For some reason, that cradle failed.
RAY: And when the engine and transmission assembly dropped down, it probably tore out the power steering lines, stalled the engine (which killed the power brakes), and the roadway probably sheared off the oil pan, which is a black thing that could have been rounded off in the process, and then bounced down the road.
TOM: It's very unusual to see the bolts that hold the sub-frame fail. They're massive. But its within the realm of possibility that they corroded due to a dozen-plus years of winter road salt. Or maybe the sub-frame itself corroded and broke?
RAY: Another possibility is that someone removed the cradle to do some work and didn't properly retighten those bolts. If you had any major under-car work done (engine, transmission, rack and pinion) in the past year or so, that could have required those bolts to be removed. And if they weren't re-tightened completely, over time they could have loosened up, worked their way out, until ... ba da bing! Major excitement!
TOM: Well, it's all oil under the bridge now, Robyn. But that's our best guess as to what happened. Glad to hear you pulled through OK, even if your Bonneville didn't.