Engine keeps cranking even without the key?

YOR MAILMAN

MEMBER
1969 FORD GALAXIE
3.8L
V8
AUTOMATIC
100,000 MILES

The car listed above is a Galaxie 500. I went to start the car from a cold start. I pumped gas a few times then tried to start. It kept cranking but wouldn't turn over. Soon as I turned the key off, the car still kept cranking. I pulled the key out and it kept going. I tried to push the gas pedal to floor to try flood it and the darn car started and ran for 10 seconds then went back to cranking. I put the key back in and tried to start it and shut it off to see if it would shut down and it kept cranking. Then as it was cranking, it started to smoke from under the hood, so I jumped out and disconnected the battery cables. This is the second time in the past eight months it’s done that. It happened once before my tune up and now. I replaced plugs, cap, distributor, wires, starter solenoid, both battery cables. Also did an oil change, and I took car to battery shop and was told battery starter and alternator all are good and working properly. I also changed the ignition key when I bought the car and this happened maybe 6 months after switching it out.

Monday, July 24th, 2023 AT 9:36 AM

1 Reply

CARADIODOC

MECHANIC
34,330 POSTS

The starter solenoid is sticking. You can get it to stop cranking by tapping it with a hammer. Be aware there's at least three different versions that Ford used, and they all look the same but they are not interchangeable. The photo below shows what it looks like. It will be mounted on the inner fender right next to the battery.

The next time this happens, unplug the smaller red wire connected to one of those small studs. If that lets the solenoid turn off, see if it begins cranking again when you plug that wire back on. If it does, there's something else causing this problem that we'll have to diagnose. We can do that without cranking the engine if you unbolt the large cable that goes down to the starter, but we're still limited to a short period of time to do that. These solenoids are not designed to be activated for more than roughly ten to 15 seconds at a time, with cooling off periods in between. The electromagnetic coil can overheat, smoke, and warp that coil so the plunger sticks and fails to release.

If a gentle tap with a hammer gets it to release, there's likely no other problem with the wiring. The solenoid just needs to be replaced.

Image (Click to make bigger)