Hey everyone, I just finished building my first engine, a small block Chevy 350. I did a full rebuild down to the block and installed it after about a year (I’m self-taught, so it took a while). Now I’m facing an issue where the engine won’t restart once it’s at operating temperature. It gets really tight, and I can’t turn the crank bolt or get the starter to turn it over. But when it cools down, it starts normally again. It runs fine if I don’t shut it off while it’s warm. Any thoughts on what might be causing this? Someone suggested the crank bearings might be too tight, but another shop said that doesn’t make sense. Any ideas?
I experienced something similar with my truck. When it got hot, it wouldn’t start until it cooled down. I ended up buying a high-torque mini starter from eBay and installed it. It’s half the size of the standard OEM starter, and the solenoid is located on the bottom instead of near the manifold. After that, I never had the same issues again.
In my case, the starter didn’t have a heat shield, and its position was too close to the exhaust manifold. The OEM starter I was using (from a C1500 with a mildly built small block) was known for heat-soaking problems.
This overheating caused increased resistance in the circuit, preventing the solenoid from firing. I’m not sure if your situation is the same since you didn’t mention whether your starter wouldn’t engage at all or just struggled to start the vehicle when warm.
I just wanted to share my experience with a similar hot start issue in case it helps. Those mini starters aren’t too expensive either.
I remember those overheated solenoids. Back in the day, you could buy Freon in a can and spray it directly onto the solenoid. Those were the good old days with the 350s and 454s in the Texas summer!
“When it becomes really tight and the crank bolt won’t turn” does this mean you can’t rotate it by hand when it’s hot? If that’s the case, it could indicate a clearance problem within the short block.
Disassemble your engine and check the crank bearings, connecting rod bearings, and cylinders. Something serious is going on. Alternatively, you could run it at 6,000 rpm when it’s hot — it’ll either self-clearance or blow up.
Heat it up and remove the spark plugs—can it rotate after that?