How to Flush Coolant
Learn how to flush coolant with our detailed step-by-step guide. Follow our easy instructions to get it done right.
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0 of 6 steps completedStep-by-Step Instructions
1 Step 1: Check Coolant Condition
Step 1: Check Coolant Condition
Inspect coolant color when cold - if brown/rusty or over 3 years old, needs flushing.
Coolant Test Strips
Test strips for checking coolant condition and pH
2 Step 2: Drain Old Coolant
Step 2: Drain Old Coolant
When engine is cold, open radiator drain cock or remove lower hose, drain into pan.
Large Drain Pan
16-quart pan for collecting old coolant
3 Step 3: Flush with Water
Step 3: Flush with Water
Close drain, fill radiator with distilled water, run engine 10 minutes, drain again.
Distilled Water
Gallon of distilled water for flushing (need several)
4 Step 4: Use Flush Cleaner for Heavy Buildup
Step 4: Use Flush Cleaner for Heavy Buildup
For dirty systems, add radiator flush chemical, run per instructions, drain thoroughly.
Radiator Flush Cleaner
Chemical cleaner for removing scale and rust
5 Step 5: Fill with Fresh Coolant
Step 5: Fill with Fresh Coolant
Fill with 50/50 mix of antifreeze and water (or pre-mixed coolant) to proper level.
Engine Coolant 50/50
Pre-mixed antifreeze for refilling system (2 gallons)
No-Spill Funnel
Funnel with adapter for bleeding air from cooling system
6 Step 6: Bleed Air from System
Step 6: Bleed Air from System
Run engine with radiator cap off, squeeze hoses to release air pockets, top off as needed.