1979 olds regency won't start once warm

This vehicle starts perfectly when cold. After driving and reaching running temperature the car will not start once shut off. It starts again perfectly after 1.5 hours of cooling off. All that is heard is a low groan as if the battery is almost dead. No starter click ,just a slow attempt to turn over and then nothing. Have replaced battery, starter, alternator and rewired the ground to no avail.the heat shield to protect the starter from the manifold heat is still in place. Any ideas?

You have covered the obvious points, so you have to try some more farfetched things.

The positive cable to the starter may be undersized or corroded.

The ignition timing may be advanced too far.

Finally, I have an Olds 455 which had the same issue. It turned out the mechanical advance mechanism in the distributor was rusty/sticky and sticking in the "advanced" position when I switched the engine off.

When hot, it stuck as "advanced" and make for hard starting, but after some time and cooling down, the arms slowly retracted and retarded the ignition timing, allowing for normal starting.

Make sure the mechanism if moving freely and the springs are in place, in the mechanism.

You have covered the obvious points, so you have to try some more farfetched things.

The positive cable to the starter may be undersized or corroded.

The ignition timing may be advanced too far.

Finally, I have an Olds 455 which had the same issue. It turned out the mechanical advance mechanism in the distributor was rusty/sticky and sticking in the "advanced" position when I switched the engine off.

When hot, it stuck as "advanced" and make for hard starting, but after some time and cooling down, the arms slowly retracted and retarded the ignition timing, allowing for normal starting.

Make sure the mechanism if moving freely and the springs are in place, in the mechanism.
Many thanks for taking te time to make your suggestions. This has plagued me for years and no mechanic wants to take the time to discover the cause of the problem. Finally, I located an instructor at a local government sponsored school who is willing to try. I will forward your message to Jim's.

Thx a bunch! Ssfox

Any sources for rubber weatherstripping (TRUNK) for my 1979 OLDS 98 Regency?

Try Steele rubber products. Fusick specialty in Conn.

Thanks for your info!