Mysterious starting problem that disappears after abt 1 hour

Recurring problem. Not the battery, I don’t think. After making multiple trips in one day or a long trip, particularly with A/C on, car won’t start, but electrical systems seem fine. After letting it sit for around an hour, it starts up fine. Our mechanic checked out and said it’s not the starter. Any ideas? Subaru Legacy with 193k miles. Thanks!

People could probably give some ideas - but you haven’t said anything yet.

What does “won’t start” mean? Does it crank and crank and crank but won’t fire up? Or do you turn the key and get nothing? Or maybe just a click? Or do you turn the key and you just get a weak rrr…rrrr…rrrr? Or what? What else do you notice, if anything, about when you try to start it? What does “electrical systems seem fine” mean? Etc.

Does it crank slowly when it wont start? How long is the car off when it wont restart? This could be an issue of an engine bearing, a fuel fault, or an overheated old ignition coil. It is always crank, spark and fuel. Please give more detail.

Doesn’t crank at all (ie I turn the key and get nothing at all, not even a click that I can hear). But all electrical features (radio, lights, power windows work fine). Thanks!

Sorry for the ambiguity. Doesn’t crank at all when it won’t start. It generally takes between 30 minutes and 90 minutes for whatever the fault is to become irrelevant and it starts up easily thereafter.

My daughter has a Subaru Legacy with the same problem. She drove for about 1 12/ hours last week. Stopped for a few minutes and then had trouble starting. Waited an hour - then the car started up fine. All week normal driving no problems. Tonight same 1 1/2 hour drive …stopped for a few minutes and then had to wait another hour. The electrical things came on but the engine did not turn over. Did you ever find out what was wrong with your car?

No luck. Took it to the mechanic and he could not reproduce the problem or find anything wrong, but it seems not to have done it since.

Sounds like classic ‘heat-soak’. Heat build-up from under hood temperatures cause the solenoid to overheat and intermittently fail.

I’m guessing when your mechanic checked it out it wasn’t screaming hot and that’s why it worked for him. Many cars have this same problem. Most of them are caused by crappy windings in the solonoid that swell and expand with the heat, causing them to stick and not engage the starter.