Car Leak Checklist
Identify and document vehicle leaks with this comprehensive guide. Learn to distinguish between oil, coolant, and brake fluid to prevent costly repairs.
Overview
Summary and key details for this checklist.
A leak is often the first sign of a failing seal, gasket, or hose. Identifying the color, consistency, and location of a fluid puddle can save you hundreds of dollars in diagnostic fees. This checklist helps you gather the data a mechanic needs to fix the issue quickly.
A basic visual inspection typically takes 15–30 minutes for a DIYer. If you take the vehicle to a shop for a professional dye test or pressure test, expect the process to take 1–2 hours depending on the complexity of the system involved.
Printable Checklist
A clean, scannable checklist view. (You can export/print from the sidebar.)
| Item | Priority | Who | Time | What to check (Pass/Fail) | If failed (Next step) |
|---|---|---|---|---|---|
| Engine Oil Pan | Required | DIY | 5 min | Dry seal around the pan and drain plug | Tighten plug or replace gasket |
| Radiator Hoses | Required | DIY | 5 min | No crusty residue or wetness at clamps | Tighten clamps or replace hose |
| Brake Master Cylinder | Required | DIY | 5 min | Fluid level steady; no wetness on booster | Tow to shop; do not drive |
| Transmission Housing | Recommended | DIY | 10 min | No red/brown drips at the bell housing | Check fluid level; consult mechanic |
| Power Steering Pump | Recommended | DIY | 5 min | No whining noise or wetness on pump/hoses | Top off fluid; inspect O-rings |
| Valve Cover Gasket | Recommended | DIY | 10 min | No oil pooling near spark plugs/top of engine | Replace gasket to prevent fire risk |
| Coolant Reservoir | Required | DIY | 2 min | Level between Min/Max; no cracks in plastic | Replace tank if cracked |
| Differential (Rear/Front) | Optional | DIY | 10 min | No thick, smelly oil on the pumpkin casing | Service seals and refill gear oil |
| AC Condenser/Drain | Optional | DIY | 5 min | Clear water is normal; oily residue is a leak | Recharge system; check for UV dye |
| Shock Absorbers | Recommended | DIY | 10 min | No oily film coating the shock body | Replace shocks in pairs |
| Fuel Lines | Required | DIY | 10 min | No smell of gas or dampness along chassis | Immediate repair; fire hazard |
| Windshield Washer Tank | Optional | DIY | 2 min | Blue/green fluid not dripping from fender | Patch tank or replace pump grommet |
| Oil Filter Housing | Required | DIY | 5 min | No drips following a recent oil change | Ensure filter is hand-tight and seated |
| Thermostat Housing | Recommended | DIY | 10 min | No pink/green crust around the housing | Replace thermostat and gasket |
| CV Boot Inspection | Recommended | DIY | 10 min | No thick grease splattered inside the wheel | Replace CV axle or boot immediately |
| Brake Lines (Hard) | Required | Shop | 15 min | No corrosion or dampness along the frame | Replace line section immediately |
| Water Pump Weep Hole | Recommended | DIY | 10 min | No coolant dripping from the pump pulley | Replace water pump and timing belt |
| Transfer Case (4WD) | Optional | DIY | 10 min | No fluid at the output shaft seals | Replace seals and check fluid level |
Use this table to systematically inspect your vehicle from front to back. Start with the engine bay, then move to the ground underneath the car, and finally inspect the wheel wells and chassis.
If you find a leak, take a photo of the fluid's color against a white background (like a paper towel). This helps the mechanic identify the fluid type immediately.
Notes
Extra context, cautions, and helpful tips.
Once you have identified a leak, keep a log of how much fluid you are adding over time to gauge the severity of the issue.
- Always dispose of used automotive fluids at an authorized recycling center; never pour them down the drain.
- Clean the area of the leak with a degreaser to see how quickly the fluid returns.
- Check your driveway for stains; different colors indicate different system failures.
- Keep a bottle of the correct coolant and oil in your trunk for emergencies.
- Note that some leaks only appear when the car is parked on an incline.
- If you have a modern car, a 'Low Fluid' light on the dash should be treated as an urgent warning.
- Browse similar checklists like Oil Change or Tires for more DIY tips.
- Always double-check that caps and dipsticks are fully seated after an inspection.
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FAQ
Common questions about this checklist.
Start from the complete car maintenance checklist, then narrow down by mileage, interval, and season.