need help from auto mechanic

[dsherw00d]

Seems security or VATS related. The wiring and starter must be OK if it works most of the time other then that scenario. Maybe a bad sensor, but I don't know what sensor would cause a no start. Maybe oil pressure or something, but no crank seem extreme. I also think you would get a code.

When this happens, the security light is not on or flashing and there are no OBDII computer codes_

[Garrett.d.w]

I had something very similar happen to my car and it turned out to be the starter motor. That being said, the difference between a 66 mustang and a 1998 chevy is astronomical.

I'd recommend checking for an OBDII code. If there isn't one, look at the starter solenoid and starter. Work your way out from there (check related sensors, etc).

Good luck

[Ether]

Originally Posted by dsherw00d

The wiring and starter must be OK if it works most of the time other then that scenario.

That was my thought process. I couldn't come up with a reasonable explanation why just that specific scenario - and no other - caused a failure to crank... and why waiting three hours would allow it to crank again.

[MrForbes]

I second the hammer suggestion. Worn brushes.

[Ether]

Originally Posted by MrForbes

I second the hammer suggestion. Worn brushes.

I hope you're right. Better that than an engine computer problem.

I'll give it a try tomorrow afternoon after the kickoff.

But in the meantime, can you think of (an even remotely plausible) reason why this happens only under the conditions described in the OP ? That's the part that's stumping me. I've repeated this about half a dozen times over the course of the past week and it always follows the described pattern.

[Mr. Lim]

Originally Posted by Ether

I hope you're right. Better that than an engine computer problem.

I'll give it a try tomorrow afternoon after the kickoff.

But in the meantime, can you think of (an even remotely plausible) reason why this happens only under the conditions described in the OP ? That's the part that's stumping me. I've repeated this about half a dozen times over the course of the past week and it always follows the described pattern.

When the starter heats up and cools down, parts of it expand and contract. With worn brushes/armature/contacts/carbon deposits, that expanding and contracting could be creating just enough clearance between contacts such that your armature loses electrical contact. Letting it cool allows things to contract, and the clearance disappears. That's why whacking it with a hammer is an effective test.

[sanddrag]

Had an electric radiator fan with similar symptoms and cause as above. It's worth a good thwak to find out.

[dsherw00d]

A quick test would be to check the 12v energizing wire going to the starter during the no start condition. In older Chevy's it's purple. If this isn't getting 12v when the key is turned, then the computer isn't sending 12v out. Another quick test to see if it's the starter locked up is to turn the headlights on and try to crank. If the juice is going to the starter and not turning it, the lights will dim. If they don't dim, then I would say no power is getting to it.

[MrForbes]

The computer is not involved in the starter circuit.

It does cut off the injectors when it wants to disable the engine.

[IKE]

There was an Episode of CAR Talk (on NPR) that covered this exact scenario, but for the life of me, I can't remember what the cause was. I will see if I can find it.