My 87 505 T was doing someting similar when I bought it. It had also sat
for several months during a cold winter. And when it wouldnt start, turning
the key had NO effect.
i finally realized that the connection of the terminal to the post on the
battery kept getting a little loose...the battery was secured , so i didnt
suspect vibration...maybe a galvanic reaction between dissimilar metals ?
there was a little bit of corrosion and the post seemed smaller, not the
terminal looser. i dunno...
What i do know is that with THAT battery, if I cleaned and sanded and
re-tightened, all would be fine for a few months, until the problem
re-developed and the connection became loose again.
(this problem once happened while i was about to pay the toll to cross the
river to go into ontario with a line up of cars behind the 505...After a bit
of quick and friendly insistence, the toll taker came out and cranked the
car while i held the battery connection in place to make good contact and
*CRANK*CRANK* it was running ! a lot easier than pushing the car thru the
toll, as she had said she would help me do while the other cars waited !)
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