MGB starting when warm issue
Discussion
1978 MGB GT. When cold spins over and starts OK, but as soon as the engine is warm and you turn it off, the engine barely turns on the starter. Battery is new (and turns OK when cold) but as soon as it's warm it's like the battery is depleted.
If I let it cool down it spins over fine again and will re-start.
Any ideas? Starter motor?
If I let it cool down it spins over fine again and will re-start.
Any ideas? Starter motor?
Could be a sticking relay, check for clicking sounds from relays when you turn the ignition on isolate these and check again if they are making a click when warm?
when its warm does the engine turn over? When it is struggling to start can you measure the battery voltage?
is the battery charging could be the alternator? have you got a multimeter? check the voltage prior to starting (this can be used for a voltage drop test if your car has not been started for a day you want 12.4 volts minimum), leave a multimeter on the battery when it is running, see if you are getting 13Volts.
Can you smell any burning? Maybe wring is arcing out ( can you smell sulfur). Check engine bay earth straps. Check wiring leading to starter motor, and wiring leading from starter motor back to the battery. Check relays + fuse box etc for burning smells.
when its warm does the engine turn over? When it is struggling to start can you measure the battery voltage?
is the battery charging could be the alternator? have you got a multimeter? check the voltage prior to starting (this can be used for a voltage drop test if your car has not been started for a day you want 12.4 volts minimum), leave a multimeter on the battery when it is running, see if you are getting 13Volts.
Can you smell any burning? Maybe wring is arcing out ( can you smell sulfur). Check engine bay earth straps. Check wiring leading to starter motor, and wiring leading from starter motor back to the battery. Check relays + fuse box etc for burning smells.
It's strange becuase the starter is engaging but just not able to turn over the engine very fast. It does just turn over and is often enough to start it.
Battery and alternator are fine and later/next day there's plenty of power in the battery to start it again.
It's almost like there's drag on the flywheel preventing the engine from turning over. I don't think it's electrical.
Strange......
Battery and alternator are fine and later/next day there's plenty of power in the battery to start it again.
It's almost like there's drag on the flywheel preventing the engine from turning over. I don't think it's electrical.
Strange......
One thing to try is to run a wire directly from the battery +ve terminal to the switch connection on the solenoid (the thin wire which comes from the ignition switch - NOT the thick one which powers the starter!!!).
If the car starts, it's a bad connection from the ignition switch, and you can either replace the ignition switch or (my preferred method) put a relay in-between the ignition switch and the solenoid.
If the car starts, it's a bad connection from the ignition switch, and you can either replace the ignition switch or (my preferred method) put a relay in-between the ignition switch and the solenoid.
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