You need to do some voltage measurements to determine whether it is a
connection or a motor problem. Whilst a low battery voltage will cause the
motor to turn slowly, a mechanical problem that causes the motor to turn
more slowly with the same battery will cause it to take more current and
hence lower the battery voltage. A bad connection that reduces the current
through the motor will also cause it to turn more slowly, but the battery
will have less load on it hence its terminal voltage will be higher.
Take a reference voltage measurement at the battery posts (not the
connectors) with the engine cold and the starter cranking the engine
normally, then take another reading when the motor is hot and the problem is
evident i.e. turning the engine slowly or not at all.
If the second reading is *lower* the problem is probably a mechanical
problem with the motor or engine not turning fast enough i.e. mechanical
stiffness but could also be a battery problem.
If the voltage is *higher* it indicates a connection problem and the full
voltage is not getting to the motor. Taking voltage measurements at the
battery posts, connectors, battery cable stud on the solenoid and a good
body ground, solenoid stud and the starter body, and the motor connection
from the solenoid - if you can get to it - and the starter body will help
break down where a bad connection is. As long as the solenoid *is*
operating and the motor *is* trying to turn, it is nothing to do with the
starter relay.
PaulH.
----- Original Message -----
From: <Cyc10@aol.com>
To: <mgs@autox.team.net>
Sent: Tuesday, July 13, 2004 4:27 AM
Subject: Starter problem when hot
> My 1970 MGB has a problem when the car is hot. When I try and start the
car
> after it has been running the starter turns very slowly and it sounds like
the
> battery has lost power. Some times it will not even turn the engine over.
> The battery was checked and it is in good condition.
>
> When the car sits a while and cools down the starter works fine and the
car
> starts right up.
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