Does this happen when both cold and hot?

Look at the starter solenoid connection and starter mount bolts.
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Do your battery cable ends have soldered connections or are they clamped onto the wire?

There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!