📋 Quick Facts
Time
1-2 hours
Difficulty
Easy
Tools
6 needed
Cost to DIY
$30-100
A leaking valve cover gasket drips oil down the side of the engine, onto the exhaust manifold (causing burn-off smoke smell), and onto spark plug tubes (causing misfires). Gasket parts run $15-60. DIY is 1-2 hours on most inline engines, longer on V-engines.
🛠 What You'll Need
- New valve cover gasket and spark plug tube seals (if applicable) (valve cover gasket kit on Amazon)
- OEM-spec RTV (Permatex Ultra Black or equivalent) for corners (Permatex Ultra Black on Amazon)
- Metric socket set with deep sockets (metric socket set on Amazon)
- Torque wrench (in-lb range) (in-lb torque wrench on Amazon)
- Plastic gasket scraper and brake cleaner (plastic scraper on Amazon)
- Shop towels (clean, lint-free) (shop towels on Amazon)
⚠ Cold engine onlyThe valve cover sits on the hottest part of the engine. Wait until cool to the touch - 2+ hours after driving.
⚠ Do not drop anything into the engineOnce the valve cover is off, the camshaft and valvetrain are exposed. A dropped bolt or socket falls into the timing chain or oil drain holes. Cover open areas with clean rags while you work.
⚠ When NOT to DIY thisDOHC V6 / V8 engines with two valve covers tucked under the intake manifold (Ford 3.5L, GM LFX, Honda J35) often require pulling the upper intake to access the rear cover. That doubles labor and adds a $20 intake gasket to the bill. Verify access before committing.
✅ Before You Start - Checklist
- Park on level, solid ground (no slopes, no soft dirt)
- Engine is at the correct temperature (cold or warm as specified)
- All tools and parts on hand BEFORE you begin
- Owner's manual nearby for torque specs and locations
- Safety: gloves, eye protection, hood propped open
📝 Step-by-Step Instructions
- Cold engine, hood up, battery negative offDisconnect battery to prevent ignition coil shorts when unplugging.
- Remove the engine cover (decorative)Pulls straight up off rubber grommets on most engines. If bolted, remove the 2-3 bolts.
- Disconnect the ignition coilsOn COP (coil-on-plug) engines, squeeze the connector tab and pull each coil harness off. Unbolt each coil (8mm or 10mm) and pull straight up. Lay them in order - they go back into the same hole.
- Move wire harness and ground straps out of the wayUnclip harness retainers from the valve cover edge. Move PCV hose, breather hose, and any vacuum lines aside. Photograph harness routing first.
- Remove the PCV valve and breather grommetsPull or twist them out of the valve cover. Inspect - replace if cracked or hard. Some PCV valves screw in (twist 1/4 turn).
- Unbolt the valve coverCross pattern from outside in. Loosen each 1/4 turn first, then fully remove. Most engines use 8-15 small bolts (typically M6 or 8mm head). Some bolts have captive washers - keep them with the bolt.
- Lift the valve cover straight upIt may stick to the old gasket. Tap each corner with a rubber mallet to break the seal. Lift carefully - old gasket sometimes stays on the head, sometimes on the cover.
- Inspect the head sealing surface and the coverBoth should be flat (use a straightedge). If the plastic cover is warped (common on Toyota, BMW), replace the entire cover, not just the gasket. Aluminum covers rarely warp.
- Clean both sealing surfaces with plastic scraper and brake cleanerNo metal scrapers. No silicone residue, no oil residue. Lint-free rag finish. Cover the head opening with a clean rag while cleaning the cover separately.
- Install new gasket into the coverMost modern gaskets are rubber and snap into a groove on the cover. Press all around the perimeter until fully seated. Replace spark plug tube seals at the same time - they share the kit.
- Apply small dabs of RTV at the cornersWhere the valve cover gasket meets a separate timing cover or cam tower, apply a 1/4" dab of RTV. This is the most common leak spot if you skip it.
- Set the cover down squarely on the headLower straight down, no sliding. Sliding pushes the gasket out of its groove.
- Hand-thread all bolts before any are torquedPrevents pulling the cover off-center.
- Torque in a cross pattern, from center outward, in 3 passesTypical spec: 60-90 in-lb (7-10 Nm) for M6 bolts. Verify FSM for your engine. Over-torque crushes the gasket and causes leaks within months. 3 passes: 30%, 70%, 100%.
- Reinstall PCV, breather, coils, harness, engine coverMatch your photos. Coils into their original holes. Snap harness back into retaining clips.
- Reconnect battery, start, check for leaksRun engine 5 minutes. Inspect the valve cover seam with a flashlight. Drive 50 miles and re-check.
✅ After You Finish - Verify Checklist
- No tools left in the engine bay or under the car
- Test the system you worked on (start, drive, check, etc.)
- Look for leaks or drips after 5 minutes of running
- Record the date and mileage in your service log
- Recycle or properly dispose of any old parts/fluids
🔗 Related Guides
❓ Frequently Asked Questions
How do I know my valve cover gasket is leaking?
Oil on the side of the engine block below the valve cover, burning oil smell after driving, oil pooled in spark plug tubes (pull a coil to check), or visible oily residue at the cover seam.
Should I use sealant on the new gasket?
Not on the gasket itself - modern gaskets are dry-install. Apply RTV only at the corners where the head meets a separate timing or cam cover (small 1/4-inch dab).
Why is my new gasket already leaking?
Most common causes: over-torquing (crushed gasket), warped plastic cover (replace the cover), dirty mating surface, or missed RTV at the corners.
Do I need to replace the spark plug tube seals too?
Yes if your engine has them (most modern engines do). Oil pooled in the plug tubes drips onto the coils and causes misfires. The seals come in the gasket kit.
How long does a valve cover gasket last?
60,000-120,000 miles is typical. Hot climates and oil-burning engines shorten that. Plastic covers often warp faster than they leak - replace the cover, not just the gasket.
Can I drive with a leaking valve cover gasket?
Yes short-term, but oil dripping on the exhaust manifold smokes and smells. Oil in the spark plug tubes causes misfires. Fix within a few weeks.