Drain the coolant and engine oil. Disconnect the battery. Take photos of every connection before you unplug it.
DIYBay 03 · Job 09
DIY head gasket replacement: should you try?
An honest assessment, not a sales pitch for parts. Most DIY-ers who attempt this without prior engine experience destroy the engine. If you have done a timing belt and a valve adjustment, it is doable. If not, hire it out.
Skill assessment
Are you ready for this?
This is an advanced repair. The penalty for getting it wrong is a destroyed engine. Use this checklist as a sanity check before you commit to the project.
Green flags
- +You have done a timing belt or chain replacement
- +You have done a valve adjustment
- +You own a torque wrench and have used it correctly
- +You have a service manual or factory wiring diagram
- +The car is not your daily driver
- +You have a clear, lit, dry workspace for at least a week
Red flags
- -You have never opened an engine before
- -This is your only car
- -You do not own a torque wrench
- -The car is a luxury European with proprietary diagnostic tools
- -You are working under time pressure
- -You expect to save money primarily, not learn
Real DIY cost
What it actually costs to DIY
Parts alone are $400 to $1,000. Tools, if you do not have them, push the first job to $700 to $1,500. The trade is your weekend (sometimes two), against $1,500 to $3,000 in pro labor.
Parts
Multi-layer steel gasket set$100 - $300
Head bolts (torque-to-yield, new)$50 - $150
Coolant (5 to 10 quarts)$20 - $40
Oil + filter (full change)$30 - $60
Machine shop resurfacing$200 - $500
Misc (sealer, RTV, tape)$20 - $40
Parts total$420 - $1,090
Tools (if you don't already have them)
Torque wrench (ft-lb)$80 - $200
Torque wrench (in-lb, for valve covers)$40 - $80
Breaker bar + impact sockets$60 - $120
Engine hoist (some vehicles)$200 - $400 buy or $40/day rent
Gasket scraper + razor blades$15 - $30
Straight edge (precision-ground)$30 - $80
Feeler gauge set$15 - $25
Coolant catch container$20
Dial indicator (for checking head)$30 - $80 (or $0 at machine shop)
Time honestly
How long it actually takes
First-timer (4-cylinder)
20 to 40 hours over 2 to 4 weekendsYou will look up every step. Plan time for going to the parts store mid-job.
Experienced DIY (4-cylinder)
12 to 18 hours, full weekendSmooth flow, you know the tools and the procedure.
First-timer (V6 / boxer)
30 to 60 hours, 3+ weekendsTighter access, more components to remove and reinstall correctly.
Pro shop (any engine)
8 to 15 hours flat-rateThey have done it before. They have the tools. They do not waste time.
Step overview (not a tutorial)
What the job actually involves
For a real tutorial you need a service manual specific to your engine. This is a high-level look so you understand what you are committing to.
Remove the air intake, intake manifold, and exhaust manifold from the head. Bag and label every bolt.
Remove timing belt or chain components, valve cover, and any accessories blocking the head.
Loosen head bolts in the reverse of the factory torque sequence. Remove the head carefully (it is heavy and the gasket may stick).
Send the head to a machine shop. Tell them to check for warpage, surface as needed, and pressure-test for cracks. Plan 1 to 5 days.
Clean both mating surfaces meticulously while the head is out. Any debris on the new gasket means a redo.
Inspect the block deck for warpage with a straight edge and feeler gauge. If warped beyond spec, the block also needs machining (or replacement).
Install the new gasket in the correct orientation (most have a 'top' or 'front' marking). Drop the head on carefully.
Install new head bolts and torque them in the factory sequence to factory spec. Most are torque-to-yield: tighten in stages plus an angle.
Reinstall everything you removed. Refill coolant and oil. Bleed the cooling system. Run the engine and watch for leaks.
Don't do this
Seven mistakes that ruin the job
If the head warped at all (most do, even slightly), reusing it without machining causes the new gasket to fail in days. Always send it out, even if it looks fine.
Modern engines use torque-to-yield bolts that stretch on first install. Reusing them means inadequate clamping force, then a blown gasket. New bolts are $50 to $150.
Tightening bolts in the wrong order warps the head as you go. Look up the specific pattern for your engine. Most pull from the centre outward in a spiral.
Bits of old gasket, oil, or coolant on the mating surface prevent the new gasket from sealing. Use a plastic scraper, never steel wool, never a sandpaper disc.
If the failure was overheating, the cause may have been the thermostat. Replace it while the engine is open. $20 part.
Most multi-layer steel gaskets have a top side. Installing upside-down blocks oil or coolant passages. Look for the orientation marking before installing.
Air pockets in the cooling system create hot spots that warp the head you just resurfaced. Follow the factory bleed procedure exactly. Some cars need a vacuum bleeder.