How to Check Your Car Engine

Park on level ground, switch the engine off, let it cool briefly, then open the hood and inspect the essentials: fluids (oil, coolant, brake), belts and hoses, battery, air filter, and any leaks; listen for unusual noises on startup, watch the dashboard for warnings, and use an OBD-II scanner if a check-engine light is on. This quick routine, guided by your owner’s manual, can catch problems early and keep you safely on the road.

What You Need Before You Start

Having a few basic tools and supplies on hand makes checking your engine safer, faster, and more reliable. The items below cover common home checks on modern gasoline and diesel vehicles.

• Owner’s manual (vehicle-specific procedures and specs)
• Clean, lint-free rag or paper towels (for dipsticks and cleanup)
• OBD-II scanner or a smartphone adapter/app (to read engine codes)
• Flashlight (to inspect belts, hoses, and hard-to-see areas)
• Protective gloves and eyewear (for safety)
• Digital multimeter (to check battery voltage)
• Funnel (for topping up fluids without spills)

With these basics, you can perform a thorough visual and functional check without specialized training, and you’ll be better prepared to explain findings to a mechanic if needed.

Step-by-Step Engine Check (Gasoline/Diesel)

Follow this sequence for a comprehensive, safe inspection. Always consult your manual for vehicle-specific directions, as some steps vary by model and engine type.

1. Safety and setup: Park on level ground, engage the parking brake, turn off the engine, and wait 5–10 minutes so hot parts cool and fluids settle. If you just drove, be cautious—components can be hot.
2. Under-hood overview: Open the hood, secure the prop, and sweep your eyes for anything obviously wrong—loose connections, dangling wires, fluid residue, or debris near belts and fans.
3. Engine oil: Locate the dipstick (if equipped). Pull it out, wipe clean, reinsert fully, then pull again to read. Oil should sit between the min/max marks and appear amber to dark brown without metallic particles or a milky look (which can indicate coolant contamination). Top up with the exact grade/spec in the manual; don’t overfill.
4. Coolant: Check the translucent expansion tank’s “COLD”/“MIN–MAX” marks when the engine is cold. Do not open the radiator cap when hot. Coolant is typically green, orange, pink, or blue depending on type; if low, use the specified coolant chemistry (OAT/HOAT/etc.)—avoid mixing types.
5. Brake fluid: Inspect the master cylinder reservoir level against marks. Fluid should be clear to light amber. A sudden drop can indicate a leak; dark fluid suggests it’s time to replace. Never let dirt enter the system.
6. Power steering fluid (if applicable): Many modern cars are electric-assist and lack this reservoir. If present, check the level/condition per the cap or manual.
7. Transmission fluid: Many newer vehicles are “sealed” and lack a dipstick; follow the manual. If your car has a dipstick, check with the engine warm and idling in Park or Neutral (per manual). Fluid should be pink-red and not smell burnt.
8. Belts and hoses: Inspect the serpentine belt for cracks, fraying, missing ribs, or glazing. Squeeze hoses gently; they should be firm, not brittle, bulging, or mushy. Look for crusted coolant or oil around connections.
9. Battery and charging: Check for corrosion on terminals and ensure clamps are tight. Measure voltage: about 12.4–12.7 V with the engine off (healthy charge) and roughly 13.7–14.7 V running (charging system working). Replace swollen or leaking batteries promptly.
10. Air filter: Open the airbox and hold the filter to a light; if little or no light passes or it’s clogged with debris, replace it. A clean filter supports power and fuel economy.
11. Leaks and drips: Look beneath the car and around the engine. Brown/black is often oil; red can be transmission fluid; bright green/orange/pink is typically coolant; clear water under the passenger side after A/C use is normal condensation.
12. Start-up check: Start the engine and listen at idle. The idle should be steady after a brief warm-up. Watch the temperature gauge; it should rise to normal operating range and hold steady. Cooling fans should cycle on/off as needed.
13. OBD-II scan: If the check-engine light is on, use a scanner to read codes. A flashing check-engine light usually indicates a misfire—avoid driving and address immediately to prevent catalytic converter damage.
14. Test drive: On a short, safe drive, note any hesitation, surging, rough shifting, or overheating. Recheck for leaks afterward.

Completing these steps gives you a solid snapshot of engine health and can prevent small issues from turning into costly repairs.

What Normal Looks Like vs. Warning Signs

Sounds and Smells

Use your senses to catch early clues. The following cues often point to specific systems that need attention.

• Ticking at startup that fades: Often normal lifter noise, but persistent ticking can indicate low oil or valvetrain wear.
• High-pitched squeal: Belt slipping or worn idler/tensioner.
• Rhythmic knocking under load: Possible rod bearing or low-octane fuel knock; urgent if loud.
• Hissing: Vacuum leak or coolant leak under pressure.
• Sweet smell (maple-syrup-like): Coolant leak.
• Raw fuel odor: Fuel leak or overly rich mixture; check quickly for safety.
• Burnt smell: Overheated oil, slipping belt, or electrical short.
• Exhaust colors: Blue (burning oil), white on warm engine (coolant), black (rich fuel mixture).

While some brief noises during cold starts can be normal, persistent or worsening sounds or odors are warning signs that warrant diagnosis.

Dashboard Indicators

Your instrument panel translates sensor data into actionable alerts. Here’s what key lights and gauges mean.

• Check Engine (solid): Non-urgent fault; scan codes soon.
• Check Engine (flashing): Active misfire; stop driving to prevent damage.
• Oil Pressure: Stop immediately and shut off the engine—low pressure can cause catastrophic damage.
• Temperature/Overheat: Pull over safely, turn off A/C, turn on heat to help shed heat, and stop the engine; don’t open the cooling system hot.
• Battery/Charging: Alternator/charging problem—limit electrical loads and have the system tested.
• AdBlue/DEF (diesel): Low fluid can trigger limp mode; refill with correct DEF.

Responding promptly to warnings often prevents secondary failures and reduces repair costs.

Special Notes for EVs and Hybrids

Electric vehicles don’t have an engine, and hybrids have high-voltage systems that require extra caution. The checks differ in scope and safety requirements.

• High-voltage safety: Never touch orange cables or components. For hybrids, follow “Ready”/shutdown procedures in the manual.
• Coolant systems: Many EVs/hybrids use coolant for the battery, inverter, and motor. Check reservoir levels only when cool and use the specified coolant.
• Gearbox/reduction unit: Typically sealed; check for leaks and unusual noises.
• 12V battery: Still critical for control systems; test voltage as with conventional cars.
• Software/diagnostics: Use manufacturer-approved apps or scanners; many issues present as alerts on the infotainment cluster.

If you’re unsure about high-voltage components, defer to a qualified technician—EV/hybrid systems can be hazardous without proper training.

Seasonal and Mileage-Based Checks

Adjust your routine based on weather and service intervals to maintain reliability year-round.

• Before heat waves: Verify coolant mixture, radiator fans, and A/C condenser cleanliness.
• Before winter: Test battery health; consider 0W-20/0W-30 oils if specified; ensure proper antifreeze protection.
• Intervals: Many modern cars use oil-life monitors; otherwise, 5,000–10,000 miles (8,000–16,000 km) on full synthetic is common—confirm in your manual.
• Timing components: Belts (often 60k–100k miles) or chains (inspect if noisy)—follow manufacturer schedules.
• Coolant/brake fluid: Replace per time/mileage; brake fluid commonly every 2–3 years.

Proactive, scheduled maintenance reduces unexpected breakdowns and extends component life.

When to Stop Driving and Call a Professional

Some signs indicate immediate risk to safety or the engine. If you encounter these, stop safely and seek assistance.

• Oil pressure light on or loud knocking
• Overheating gauge pegged or steam from the hood
• Flashing check-engine light
• Fuel odor with visible leakage
• Large, sudden fluid puddles under the vehicle
• Severe loss of power, heavy smoke, or violent shaking

Continuing to drive under these conditions can turn a repairable fault into a major engine failure.

Quick Checklist to Document Your Findings

Keeping brief notes helps track trends and supports warranty or repair discussions. Record the following after each check.

• Date, mileage, and ambient temperature
• Oil level/appearance and top-up amount
• Coolant level and any visible residue
• Battery voltages (off/idle) and terminal condition
• Belt/hoses status and any cracks/bulges
• Leaks found (color, location, size)
• OBD-II codes (if any) and freeze-frame notes

These notes make it easier to spot patterns—like gradual coolant loss or declining battery health—before they become urgent.

Summary

To check your car’s engine, work safely on level ground, inspect key fluids, belts, hoses, and the battery, look and smell for leaks, monitor gauges and warning lights, and scan for codes when needed. Follow your owner’s manual for model-specific steps and service intervals, and seek professional help immediately for oil pressure loss, overheating, fuel leaks, or a flashing check-engine light. Regular, methodical checks are the simplest way to preserve performance, safety, and longevity.

Do I check engine oil when the car is hot or cold?

The best time to check your engine’s oil is: When the Engine is Cold: It’s typically recommended to check the oil when the engine is cold, ideally after the vehicle has been parked for a few hours or overnight. This allows the oil to settle back into the oil pan, providing a more accurate reading.

How to check if a car engine is ok?

To check a car’s engine health, listen for unusual noises, check for fluid leaks under the car, inspect the oil dipstick for milky or gritty oil, and look at the exhaust for excessive smoke. On a cold start, ensure the engine starts immediately and runs smoothly. A professional mechanic can perform more in-depth tests like a compression test to measure cylinder health or an oil analysis to detect internal wear.
 
Quick Checks (No Tools)

• Listen to the Engine: Opens in new tabStart the engine from cold. It should start immediately and run without loud ticking, rattling, or excessive vibration. 
• Check for Leaks: Opens in new tabLook under the car for any puddles or fresh spots, which can indicate leaks of oil, coolant, or other fluids. 
• Inspect the Oil: Opens in new tabPull out the oil dipstick and check the oil’s condition. It should be clean and not appear milky, foamy, or gritty. 
• Look for Exhaust Smoke: Opens in new tabObserve the exhaust fumes. White or gray smoke can indicate a blown head gasket or other coolant issues, while blue smoke suggests the engine is burning oil. 

With Tools (or Professional Help)

• Read OBD-II Codes: Connect a code reader to scan for stored trouble codes, which can point to underlying engine issues. 
• Perform a Compression Test: This tool measures the compression in each cylinder to reveal issues with piston rings, valves, or head gaskets. 
• Get an Oil Analysis: Send a sample of the engine oil to a lab to detect high levels of wear metals or contaminants like coolant, which signal internal damage. 

During a Test Drive 

• Accelerate Normally: During a test drive, ensure the engine accelerates smoothly without hesitation or lag.
• Monitor Engine Temperature: Check that the engine doesn’t overheat or lose power during sustained driving.

When to Call a Professional
If you find any of these signs, it’s best to consult a professional mechanic: 

• Significant fluid leaks.
• Persistent smoke from the exhaust.
• A rough-running or misfiring engine.
• High levels of wear metals in an oil analysis.
• Poor compression readings on one or more cylinders.

How do I check my vehicle engine?

To find the size of your engine, you will need to check the manufacturer’s website or use a reliable VIN decoding tool like the one offered by GoodCar. Focus on the eighth character of the VIN, scanning from left to right. This character will give you the exact engine size and type that is in your vehicle.

How do I inspect the engine?

Engine Mechanical Items.
Make sure pulleys are properly aligned and unbent, and that bearings and bushings are undamaged. Inspect drive belts for signs of cracking, glazing and damage, and check for proper tension. Check all hoses for cracks and leaks. Clamps, connectors and couplers should be securely in place.