90 Buick Century cranks slow, won't start

My 1990 Buick Century (V-6, 3.3) has been cranking sluggishly lately. Most recently it got worse: It turns over a couple of times and stops. It's random -- sometimes it starts, sometimes it doesn't. But even when
it starts, the cranking is slower than it used to be. Suspected the battery and poor battery-terminal connections at first. Tried 3 different batteries (one brand new), cleaned the terminals -- same problem. My next suspect is the starter -- terminal connections or the motor itself. Haven't had much experience with starters -- any piece of advice before I crawl under the car? Thanks. Svilen
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I would take the starter out and then connect it directly to the battery (battery disconnected from the car) with jumper cables and with your foot (or a helpers foot) securely on it, make the connections. The motor should snap when activated and want to come out from under your foot. If it doesn't have that kind of torque then it's probably bad. While your at it I would replace the battery cables as well. Also look for any shims that are between the starter and the engine block where bolted on. If there are any you'll want to reuse them.
Brian
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Svilen Stoicheff wrote:

I've noticed Chevys, in particular, have very skimpy grounds. To get maximum current to starter, make sure ground cable goes directly to block, not to some painted bracket. Add a jumper cable from frame rail to block. A Ford starter cable has lugs on both ends, and is my recommendation for a no bull ground.
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