Recently I picked up an extremely high mileage but well taken care of 740 turbo wagon. Recently the temp gauge started going nuts whenever the throttle is applied, I figured it to be a dying sensor or a supply voltage issue.

After a few days of this I smell an odor as I'm driving behind a pool service truck, I take it to be chlorine or some such. A day or two later I catch a whiff of the same smell on the way into work, fast forward to the end of the work day and the car won't start. No cranking whatsoever. Windows raise with vigor, no burnt fuses I can find.

I had the starter and the alternator tested, haven't yet checked voltage at the battery but I expect it to be fine. The starter checked out but I the alternator did not. I discover a crack in one of the two components bolted to its back, not the regulator, the ignition capacitor which is marked 0290800036.

I'm getting the all clear from both the tranny and ECU when I jump the diagnostics port so I'm hoping that they are fine.

Any guidance on what I should look to next?

 

what year is the car? reason being is some of the later 740's have a crankshaft position sensor located behind the cylinder head that has a tendency to go bad.... a bad alternator will not keep a engine from starting...

the next step would be- check to see if you're getting spark and/or fuel...

 

It is a 91. I've read about the failing crank sensors but my understanding was that the engine would turn over but not start when they failed.

I'm not concerned that the alternator is keeping the car from starting, I'm curious to know if that part failing on the alternator could lead to it outputting too much voltage and destroying some component or components.

There was definitely an acrid odor in the car whilst driving but I can't locate the source. I can't check spark or fuel as the engine doesn't crank thus no RPM signal to trigger them. About the only thing I can do is check for the fuel pump being primed.

Here is my list of possibles for no signal to the starter:
Bad ignition switch.
Neutral safety switch.
Low voltage; bad battery, ground, poor connection at battery terminal.
Blown fuse or relay, but which?

 

sorry, I misunderstood thee part of it not turning over at all...

def have the battery tested... If the alternator had been over/undercharging, it may have been sulfating and cooked a cell plate....

if batt checks out, next steps I'd say would be:
have someone hold the key in the "start" position, and check voltage on the smaller solenoid wire....

backtrack from there-neutral safety, ignition switch