What Causes the Starter Motor to Fail When the Engine is Hot but Starts Easily When Cold?
2 Answers
Difficulty starting a hot engine may be caused by fuel injector leakage, a faulty carbon canister purge valve, or fuel quality issues. Below are the reasons and solutions for hot engine starting difficulties: 1. Fuel injector leakage: While fuel injection is normal, leakage constitutes additional fuel supply. The more severe the injector leakage, the richer the air-fuel mixture becomes, leading to hard starting when the engine is hot. 2. Faulty carbon canister purge valve: During hot starts, fuel atomization is normally sufficient without requiring additional vapor. If the carbon canister continues supplying vapor to the intake tract, it creates an overly rich mixture, making starting difficult. 3. Fuel quality: After a hot engine shutdown, the engine compartment remains at high temperature. If the fuel is highly volatile, it can form excessive vapor pressure in the fuel rail. When this pressure exceeds the fuel system pressure, vapor lock occurs, causing the injectors to deliver overly lean fuel vapor and resulting in starting difficulties.
As an experienced driver who has handled many cars, I've encountered similar issues. When the engine is hot, the starter won't turn, but it starts immediately when cold. There are usually several common reasons. First, the battery's performance weakens in high temperatures; older batteries have reduced discharge capacity in hot weather, providing insufficient voltage to power the starter. Second, the starter itself may be the issue—thermal expansion can cause internal coils or bearings to expand and jam. Last time, replacing the starter solved my problem. Third, electrical connections may loosen when heated, with copper wire expansion worsening contact. I recommend first checking the battery's lifespan and whether the terminals are corroded. Testing the voltage drop during a hot start can pinpoint the issue. Prevention is key: regularly clean battery terminals and ensure the starter has proper cooling. Safety first—don't push your luck on the highway; get it checked at the first sign of trouble. Cars over five years old are more prone to this, so maintenance shouldn't be neglected.
