97 GP SE 3.8 NA 176K miles
When I turn my key 4 out of 5 times my car does not start. Here's what I hear when I turn the key:
-A rapid ticking noise from what I'm assuming is the starter solenoid.
-The ticking will continue for about a second if I keep the key turned, and gets weaker the longer I keep the key turned until it can no longer be heard.
-This problem has affected nothing else as far as I can tell. Once it's started I have zero problems keeping it running.
Note: I recently replaced the starter on a 2002 Ford Taurus, the symptoms of which were presumably only the starter motor going bad: (loud strong firing and releasing of the solenoid with the turn and release of the key, respectively, but no starter motor turn at all. New starter and solenoid solved that problem.
I've never heard a starter fire rapidly and get weaker after about a second until my car started doing this.
Two weeks ago I unbolted all the wires from the starter and solenoid. The contact surfaces were bright green with corrosion and/or rust. I used a set of small files to completely remove all corrosion. All contact surfaces and the posts were shiny when I put it back together. The car started right up over 30 times with no incident for about 2 weeks. Now the problem is back.
Is there anything else that could be making this rapid ticking noise? I'm planning on replacing the solenoid. Any help is appreciated.