White smoke billowing from your 2020 Chevrolet Tahoe's exhaust after driving through flood water indicates water is being burned in the combustion process. This is a serious warning sign that water entered the engine and potentially caused internal damage.
What White Smoke Means
White smoke is steam from water vaporizing in the hot exhaust. Normal exhaust on a cold start produces light white vapor that dissipates quickly - this is condensation. Heavy, persistent white smoke that doesn't clear indicates significant water presence, either from flood ingestion or a head gasket failure that allows coolant into cylinders.
Sources of Water in Engine
After flooding, water enters through the air intake. If the engine ran through the water, some water reached the cylinders. Less severe than hydrolock, this water is now burning off. However, water in the cylinders can also damage head gaskets, allowing coolant to enter - creating ongoing white smoke issues.
Assessing the Damage
Short-term white smoke that clears may indicate the water is burning off with minimal damage. Persistent white smoke suggests head gasket damage or cracked head. Check coolant level - if dropping without visible leak, it's entering the engine. A chemical test can detect exhaust gases in the coolant, confirming head gasket failure.
What to Do
Do not continue driving with heavy white smoke - this worsens any existing damage. Let the engine cool, check oil for water contamination (milky appearance), and check coolant level. Have the engine professionally inspected before extended operation.