Classic Car No Crank No Start

Starter-Relay-and-Solenoid.JPG
External Starter Solenoid. Photo by Mark Gittelman

One of the downsides of owning a classic car is they sit for long periods of time. As we head towards the automobile with key in hand, we often wonder if she will fire up or not. Professional mechanics divide a no start condition into two main categories. There is the scenario where the engine spins over nicely, but refuses to start. This issue is covered in an article about the crank, no start problem.

Here we're going to talk about the second group, which is when a classic car won't crank over at all. Mechanics refer to this as a no crank no start condition.

Why Cars Won't Crank

Of course, the number one reason for an engine not the crank on any car would be a problem with the battery. Since classic car owners are familiar with how to treat a battery during long-term storage we'll just touch on this briefly and then move on. When storing cars for long periods of time it's a good idea to remove the battery from the automobile. If possible store them in a clean and dry environment with moderate temperatures. This way when it's time to fire up the vehicle the battery can be charged, tested and installed.

If the vehicle will not crank when the battery is known to be good, we won't have to backtrack and check it again. When it comes to vintage cars and batteries the biggest problem is when unexpected long-term storage occurs.

Sometimes we park our classics expecting to use them in the near future. Nevertheless, life gets busy and weeks, months and years go by without the opportunity to start and run them. In this situation it’s recommended to replace the battery and the cables so we know our cranking voltage will be adequate.

My Classic Car Won't Crank

Although the battery and the starter motor are often the root cause of a no crank condition, many classic cars have a few separate components between these two devices. On automobiles from the 40s through the early 1970s it's common to have an external starter solenoid. The mounting area can vary, but a common place is the upper part of the firewall. On classic Ford, Lincoln and Mercury cars they're located on the passenger side inner fender skirt. Many models have a separate relay that activates the solenoid. Although these devices are reliable the designers probably didn't plan on them lasting more than sixty years.

In a typical system the starter relay receives a signal from the ignition switch to connect battery power to the starter motor. Inside the relay a set of electrical contacts allows current to flow to the starter solenoid. If these contacts become corroded or extremely worn, they may not get the job done. An external starter solenoid, unlike the relay, carries high voltages. For this reason these are often large in size and have heavy gauge wiring attached to the lug style terminals. When the key is pushed to the crank position there should be voltage on both sides of the solenoid.

If there is no voltage on the cable that runs to the starter, yet there is voltage on the battery side terminal than the solenoid has failed.

Tips for Diagnosing Starter Relays

Sometimes mechanics will try to get a jump on diagnosis by turning the key to the crank position and listen for a clicking sound. Although this test does have its merits, you will need to perform further diagnosis before replacing any components. One thing the click noise test verifies is that power is flowing through the circuit. However, it's possible for a starter relay to make a click sound yet fail to deliver current through the closed contacts.

Fortunately this electrical device is easily tested with a meter or 12 V test light. Classic car starter relays will often have four wires in the connector. With the ignition key in the on position there should be power on the heavy gauge red wire and a strong ground on the black wire.

When the ignition key is pushed to the crank position you should have an additional 12 V going into the relay and 12 V comes out on the wire that runs to the starter solenoid.

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Gittelman, Mark. "Classic Car No Crank No Start." ThoughtCo, Jan. 22, 2016, thoughtco.com/classic-car-no-crank-no-start-726173. Gittelman, Mark. (2016, January 22). Classic Car No Crank No Start. Retrieved from https://www.thoughtco.com/classic-car-no-crank-no-start-726173 Gittelman, Mark. "Classic Car No Crank No Start." ThoughtCo. https://www.thoughtco.com/classic-car-no-crank-no-start-726173 (accessed November 24, 2017).