Two questions regarding my fiancee's '76 300D daily driver:

1. it isn't being driven at the moment, because it won't start. She says it tried to crank, then spat a bunch of smoke from under the dash and hood, and after that turning the key gets a single click, then no response at all. I took a careful look around, and the only thing I noticed amiss was that the plastic insulation on the throttle cable is melted, as though it had heated up. Any ideas?

2. Periodically when driving, usually after going over a large bump, there's a loud KNOCK-KNOCK-KNOCK from beneath the car, right under the passenger compartment. Am I correct in assuming that there's a flex coupling on the driveshaft that's worn out? (I had a BMW 320i with a similar issue once) And if so, is it (like the BMW) something that's relatively easy to repair at home?

Thanks for any advice!

 

This sounds almost like an issue of a bad engine ground. The current (huge amps pulled to try to start) went for the best path it could find, the throttle cable, which isn't designed to handle that current load.

As far as your knock knock knock, the best thing to do is a visual inspection. Heck, it could be the ground strap has come off and is slapping the bottom of the car.