I have an 89 camaro iroc z 5.0l. It usually starts up fine unless i drive it for more then 15 minutes and shut it off and try to start it back up a few minutes later. When i turn the key nothing happens i cant even hear the starter. But if i let the car sit for over 2 hours or get a jump it will start right up. Ive had the battery alternator and starter replaced and im running out of ideas and money. If anyone has some suggestions it would be much appreciated.

 

starter solenoid may be overheating due to its proximity to the exhaust manifold
solution is heat shields, you can buy a heat shield to cover the starter solenoid to prevent it from absorbing as much heat from the exhaust manifolds

 

Check your exhaust for any cracks. That heat will get well over 500 degrees and if it is breathing on your starter, then there is your issue. This is what was wrong with mine, due to a giant 8" crack right near the starter.

 

Yea, if nothing happens with the turn of the key it is a starter solenoid. I've had them go bad in a lot of FORD products and the first sign was they would randomly work. If it would not activate with the key turn I would open the hood, leave the key turned forward and, like an idiot, use a screwdriver to connect the terminals and it would start the vehicle woth a few sparks. Not safe but it got me going.

 

You know, does your key have the computer chip VATS system? I had an '88 GTA and I could have sworn it had the starter cut-off VATS. That could be an issue also if you have it. I cant remember when GM used it.

 

easiest solution sounds like heat. too odd to let it sit and start. the only thing that makes me think otherwise is that you pointed out that if you jump the car it will start right up.

so drive the car for 15 min, turn it off and then if it won't start your saying you can immediately jump start it to get it going? if that's the case it's definately a power issue and not a heat issue.

unfortunately what your describing doesn't add up. you might also check the components you bought, just because you bought them new doesn't make them in good shape. i've bought plenty of bad "new" parts from the local parts store over the years. it's a pain..

after 2 hours of sitting check the battery. if it's holding it's voltage you shouldn't need to jump the car to get it started. even if the alternator is bad a good battery should get you started at least.

assuming all your components with power are good go after the solenoid and the ignition

 

if its the starter solenoid then your battery is good putting out 12.6 volts and its rated cca, if you jump it, you get another good 12.6v battery with its rated cca

when the starter solenoid gets hot, its resistance goes way through the roof which means the amperage from one battery is used up by the starter solenoid and very little is left to turn the starter motor, jumping the battery will give you theoretically 2x as much amperage, so you could get enough amperage to the starter motor to get it running

this is my theory, not actual fact

 

You're right, but the logic is backwards. When resistance goes up in the solenoid due to heat, it conducts less current. So it can't energize and kick current to the starter motor, so starter motor never even tries to draw current. Reason jumping can help is that it can increase the available voltage enough to reach the point where voltage overcomes the increased solenoid coil resistance, and it conducts enough current to energize.

To the OP, also check for loose connections (including crimps) or corrosion, especially the ground cable. Any that are loose would have those symptoms, ok when cold, unable to feed enough current when hot.

Also might be a flaky neutral/safety switch. To test it, make a small U out of a piece of a large paper clip. Stick it into the connector at the N/S switch with the large gage purple wires, insulate with tape. This bypasses the switch, if issue is gone, you know the source.

 

forgot all about the neutral safety switch... i hate those damn things. great point.

 

when you jump a car you connect positive to positive and negative to negative, that increases amperage not voltage, voltage remains at 12.6, amperage doubles

if you connect pos to neg and neg to pos you get 25.2 volts with roughly the same amperage, and the amperage will pass through the jumpercables, heating them up and increasing their resistance

 

Connecting batteries in parallel increases available current reserve, it does not of it's own increase current flow. Current flow is strictly determined by Ohm's law. E/R=I. You could have a million fully charged batteries connected in parallel and the current flow would be exactly zero if circuit resistance was infinite.

The reason I said that jumping "can help" in a hot solenoid situation is that a vehicle with a running engine will typically measure higher voltage than a vehicle with a non running engine, across the battery. That's with a fully charged battery in the vehicle to be jumped.

So if the non starter has 13 battery volts available, and if the hot solenoid has a (circuit + coil) resistance at the time of say 2 ohms, current flow would be 6.5 A thru the coil. If you hook up a running car with figure 14.5 volts available, current flow would go up to 7.25 A thru the solenoid coil, maybe enough to get the hot solenoid to energize.

13 & 14.5 vdc are typical readings across the battery on a vehicle with the engine off & on, with a good battery/charging system.

 

i should have been clearer
the amperage cannot double, since amperage is determined by the applied voltage yto a circuit with given resistance

what i did mean to say is that the available amperage effectively doubles when connecting the batteries in parallel
it is this statement i have a problem with

Reason jumping can help is that it can increase the available voltage enough to reach the point where voltage overcomes the increased solenoid coil resistance


your not increasing availabloe voltage
voltage stays the same