Big Block won't restart when hot


#1

I have a 454 rebuilt engine in the car. It starts good when cold. But after running for any length of time, 15+ minutes, the car acts like the battery is dead and will not turn the crank. If I wait 30 to 60 minutes, it will start. The battery and alternator are less than 6 months old, but hadn’t been used very much. Any suggestions on what the issue might be??


#2

A dragging starter suffering from heat soak more than likely.


#3

Can you hear a click sound from the starter solenoid when you try to start the engine?


#4

I’d bet on the heat-soaked starter too. Install a heat shield between the starter and those nice new (hot) headers you put on the 454 when you installed it.


#5

No clikcs, more of a really hard attempt to crank and then nothing.

Others have posted a comment on heat soak. I am going to try the heat shield suggestion and see where it goes.

Thanks to all for the advice.


#6

ditto on the heat-soak. Heat shield and a wrap on the headers it you have them. OR try one of the newer smaller but high torque starters. It could be that you have a bad starter and you need a new one.


#7

If your starter is heat soaking, a heat shield or starter blanket is not going to be the total cure.
This means your starter is also on the way out.
An amperage load test should be performed on the starter while the engine is cold.

If you change the starter then you also need to be aware of the shim package that is used on the starters.
If the starter makes a scraping type of sound when energized then you have to add a shim (thinnest one) and see what happens. If it still scrapes, then remove that shim and try a thicker one until it’s quiet.
Ignoring this problem will lead to starter gear failure and also flywheel tooth failure, with the latter meaning the trans has to come out.


#8

I had the same problem on a 454 Pick up I had a while back. The Factory but a cheap sheet metal “shield” on top of the solenoid. Over time it rusts away, and even if it remains if you replace the starter it is easily over looked, as it was in my case. I had a brand new starter put in, and my mech at the time did not put on the heat shield (told me later it had rusted). Any way I immediately had the same problems as you describe, I started with a heat wrap, and that worked ok. Still not perfect. I ended up having a muffler/fab shop build a new heat shield to fix the problem completely.