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E28 (1982 - 1988)

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  #1  
Old 06-24-2018, 01:52 PM
teamleader teamleader is offline
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Location: Auckland, New Zealand
 
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Mein Auto: 330i
Engine wont crank

Hello Ive replaced the engine in my E 28.I now find the engine wont crank using the key, the starter is ok, it does crank if I connect a cable to the battery and starter motor, and starter to solenoid.
And if that is not enough, the starter does not engage the flywheel
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  #2  
Old 06-27-2018, 05:05 PM
AutohausAZ.com AutohausAZ.com is offline
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Mein Auto: BMW M5
If everything was working prior to engine swap sounds like undercharged battery or a wiring connection. Your most likely culprits.

I would always start by making sure I had a fully charged battery because starters AND relays can be temperamental if not over 12V available. Some relays may not close at 12.0v but work fine at 12.1V. I'd then verify a good system ground with clean connections. IF battery and ground are good it sounds like two separate issues, the key switch is not completing a circuit to the starter and the starter is not engaging properly.

Those older starter systems are pretty basic. The ignition switch feeds 12V to the starter relay when you turn the key, the relay closes to feed battery voltage to the starter solenoid, and the solenoid engages the drive which then turns the flywheel.

Check to see if you have 12v at the starter when the key is turned, check wiring and the relay if not. Is the relay getting voltage on the signal leg when you turn the key? Does it have battery voltage on the input leg? If all else fails test the ignition switch and make sure there is voltage on the output there when you turn the key.

As for the starter not engaging the flywheel, pulling the starter and bench-testing it would be preferable to be certain it is functioning properly. Hard to see on the car if the starter gear is moving correctly. Again, without enough voltage it may spin but not engage. You hear it spin but if not engaging the flywheel there is no resistance and 10V might spin it without moving the gear to engage the flywheel.

Hope you find the battery just needed a fresh charge....
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