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Discussion Starter #1
I have a 1972 240Z. When I shut off the ignition, it doesn't always shut off and there is a grinding noise - like metal against metal. My husband just put in an entire new ignition assembly with new keys but that did not take care of the problem. Is it perhaps the starter? Or something else. Any ideas?
 

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If you said this happens at start UP, I would suggest you check the starter motor and the flywheel teeth.

You know how it sounds if you turn on the key to the start position while the engine is already running? Is this what your noise sounds like? Maybe there is a problem with the way the ignition is wired -- something is shorting out when the key is turned off?
 

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Thanks for the response but it is not the timing. Tune-up, timing, etc was recently done to my satisfaction. The engine runs great.
 

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Yes, that is more what the noise sounds like - turning to start position while engine already running. I'm not sure it would be the ignition wiring - it would be coincidental that it would happen with the old set, and now the new. When the car is shut off, it does not shut off completely (and it is not the timing). I'm getting a back noise I think from the starter or the solenoid. Maybe the solenoid is not engaging and turning the car off? Does that sound possible? I can fiddle with the key a little and it shuts off. So...what to do? Replace solenoid? Replace starter? Both? Or is there some rigging that can be done?
 

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It sounds like it could be dieseling, this is when a car runs lean, the valves get too hot, and when you turn the key off, it runs roughly for a while. This can also happen if you get carbon buildup on the top of the pistons. It'll make bad sounds til it finally dies. You can usually tell pretty easily if this is the problem, pull all of the plugs( one at a time) and look at them..they should be light brown, a real light brown or white color indicates a lean condition. It's possible for the front three to be different from the rear three cylinders.
Another thing you could try, remove the battery ground while the car is running, then turn it off. It'll remove all chances for an electrical problem to turn the starter on.

Chrome
 

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hello from reading your post if i were you and this was happening on my 71 240z i would check the wiring to the starter and the soloniod..i maybe wrong but i always thought that the solenoid was to start the car only, it ingages when it recieves electrical current then disingages once the current supply is cut off ( like when the car is running the voltage secess to go the starter solinoid and is bypassed untill the car is started up again) so....it seems to me that even though your trying to shut the car off somehow the ignition is attempting to restart the car so the car continues to run untill you fiddle with the key and you get the metal grinding noise because the car is already running...makes sense to me !? so check the wiring at the solinoid and in the ignition . maybe your getting some arcing going on at the starter solinoid?? like when you take a scew driver and place it across the solinoid and starter electrical hook ups the engine will turn because your ingaging the solinoid...anyway just my guess< good luck michele in FL. 71 240z
 
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