Starter heat soak?

[Gregs///M]

Follow Jlevie's advice. I had this problem on my e34, e30, and e28. Replace with Bosch re-manufactured starter, problem went away. I also recommend replacing your engine ground cable too.

[lukeADE335i]

Just thought I'd revive this thread to post a resolution.

On my car I had these same symptoms (and posted to this thread) - anyway after replacing the starter, earths (and adding extra ones), unloader relays and connectors on the black / yellow and green / black wiring from the starter I still had issues (the problem was always improved for a while with these different fixes and then the issue came back).

The final solution was to replace the whole Black / Yellow wire from the ignition to the starter. If you've done an auto to manual swap, and bypassed the starter relay there are more connectors in this circuit that can get corroded / fail / have bad contact than in a manual car. Bypassing all these, and running a wire direct from the C200 connector in the steering column to the starter - exactly like a the manual e30 wiring harness is from the factory - sorted the issue.

Seems the Black / Yellow wire can't push through enough current for the unloader relays to work properly if the wire is a bit old & dodgy.

Hope this helps if you're having similar issues.