1978 Mark V Solenoid Issues

Bill,
I have read most if not all of your posts on your blog. I have an issue with the car. I have replaced:
Starter
Alternator
Solenoid
Voltage Regulator
Grounds
Ignition Switch
Battery is charged with 12.5 Volts.
When you first start the car, everything is great. After the car gets to operating temp of just hot, you turn the key off and wait a minute. Restart the car and the starter stays engaged.
I have replaced the solenoid 4-5 times on this car within the last 2 months. The car has not been driven more than 200 miles in that time. Most of this is while it was sitting in my driveway while we continued to trace wires and replace bad grounds.
To no avail..I thought I would ask for some help from someone who knows these cars. That would be you..;-)
Thanks for any help you can provide,
John
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Hello John –
At Lincoln Land we have also experienced solenoid problems such as you are describing. Have you been using the same brand during these failures? We have found that some solenoids have been of a low quality or inconsistant quality from some suppliers. I would first check though if the wire that activates the solenoid is in fact at 0 volts when the ignition key is released from the cranking position to the run position. If it remains at battery voltage after the engine starts and the key is in the run position the starter of course will remain on and cranking. This test of course must be done and is only useful when the issue is occuring. We have also found that a high starter draw, a dragging starter, an undercapacity or failing battery can surprisingly cause some solenoids to overheat and fail. Another item that is often overlooked and easy to overlook is the battery cables and starter cables. Some faulty cables as well as grounds can appear real fine but be in fact bad. Some of the above can cause a solenoid to fail in the closed position (contacts inside have overheated and fused closed) so therefore I would revisit some items that you may have already checked. Finally do not overlook the possibility that a newly rebuilt starter could be drawing too much power and causing the solenoids to fail. I hope that the above helps you to solve the problem.
Sincerely,
Bill