My 97 blazer won't start once it has been driven and the engine is hot. depending on how hot the engine got, it may take an hour or 2 for it to cool off and then it will start right up. we had to replace the alternator about a month ago(with a rebuilt one), have replaced the battery, coil wire and coil. any suggestions on what to check next?

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There are two temperature sensors on the engine. One is designed to send information to your engine control module. The other information to your gauge in the vehicle. It would be a good idea to check your coolant level as on this model they are noted for leaking coolant from their intake gaskets. Also when engine has been driven for a while see if the upper radiator hose is hot to the touch. You may have a thermostat that is stuck open causing your condition.

sometimes when the starter gets hot it won't allow the Bendix to engage properly.

You have an intermittent problem in your start circuit. I'm sure you also have some choice phrases to describe it, go ahead and vent, we have all encountered frustrating problems.
The reason shops can't find it is because it isn't happening when they look at it. Anytime a hot engine is shut down a lot of heat is generated in the engine compartment. So opening the hood helps yours cool down faster and start quicker, a good clue. I believe if you had it at a shop when it won't start, they might find it. First thing they would check, or you could if you have a voltmeter or testlight, is if power is reaching the starter from the ignition switch in cranking position. This is the small wire on the starter solenoid. If there is power there when the engine won't crank, quickly reconnect the wire and verify if car will crank or not. If still nothing, it may be a poor ground wire(battery or engine ground) or a poor battery cable, since you know the starter is good. If you reconnect the wire and it suddenly starts working, it may have just been a loose connection on the wire you pulled off. If it keeps happening when your hot engine is shut off, test may have been invalid-intermittent problem has only now come back, so run the same test again.
If you or a tech ever find no power on the solenoid wire in START, that narrows it down to the path from the ignition switch to the starter solenoid. One needs to trace that path, looking for where the power is stopped. A couple of possibilities are the starter relay and the neutral safety switch. You could try a new inexpensive starter relay and see if that solves it. If not, then further testing needs to be done before giving up or throwing some expensive parts in and hoping. But you have narrowed it down which helps. It could be some arcane problem like a ground source for the starter relay, or who knows what. Have the start circuit checked, and it would be easier if the no crank condition is present when checked. Good luck.

HI,

DOES THE STARTER EVEN TURN OVER OR ITS JUST DEAD NO NOISE! IF SO THE THE STARTER IS JUST HOT FROM THE ENGINE HEAT AND THEN HAS A CHANCE TO COOL OFF.
REPLACE THE STARTER IF THATS THE CASE CAUSE IT WILL EVENTUALY DIE COMPLETLY AND NOT RESTART!

CHEERS!

It depends on some factors. The cooling systems are huge in the 4.3 engines there is also problems with the radiator they leak. and problems with the intake manifold gasket if it ever not ever over heats but gets to hot they sarrt to leak into the cylinders. So check the cooling system check the oil for antifreeze in that and oil in the antifreeze. AS long as you have not driven it for thousands of miles with this happening you can save it. Although it won't be cheap to do so but then again a rebuilt engine is around 3000 thousand dollars just for the engine and you would need to do the entire cooling system to so its your call good luck

I had this same problem with a early 90's Pontiac Grand-Am. I was asking around for this same problem and found out that it was the coil pack that was getting hot and causing it to lose spark. Once it cooled down it would start again. I replaced the coil pack and did not have the problem again.

Check the electronics in the distributor. Chevs are notorious for the electronics going bad inside of the distributor.

Your starter selonoid is going bad when it is heating up it doesn't work. Replace the complete starter.

Check for spark. Also listen for the fuel pump to kick on or spray starting fluid in the throttle body to see if it starts. If the fuel pump isn't kicking on then its your fuel pump and its located in the tank