How to Replace the Head Gasket Set on a 5.7 Hemi
TL;DR: A 5.7 Hemi head gasket job is not a difficult engine to work on, but it is an unforgiving one to rush. The Gen III Hemi is a pushrod V8 with aluminium heads on an iron block, two spark plugs per cylinder, and — depending on year and application — MDS cylinder deactivation and variable cam timing, all of which change what you disturb on the way in. The factory head bolts are torque-to-yield and are not designed to be reused. Confirm every torque value, tightening sequence and fill-and-bleed step against the factory service manual for your exact year and application.
First, confirm the head gasket is actually the problem
Head gaskets get blamed for a lot of faults they did not cause. Before you commit to a teardown that will take a weekend and a stack of parts, prove the failure.
Symptoms that genuinely point at a head gasket:
- Coolant loss with no external leak. Nothing on the ground, no crust at hose joints, no wet spot at the water pump weep hole, but the bottle keeps dropping.
- Combustion gases in the cooling system. A block tester using the colour-change fluid over the open filler is the cheapest reliable confirmation you can do in a driveway.
- Steady white steam once fully warm, with a sweet smell, that does not clear the way ordinary condensate does.
- Milky oil on the dipstick and under the fill cap, with no other water-intrusion path.
- A cylinder that will not hold pressure on a leak-down test, with air audible at the radiator filler or escaping into an adjacent cylinder.
Symptoms that usually are not a head gasket: a rough idle with a misfire code but no cooling symptom at all (look at coils, the plugs — remember there are two per cylinder — or the valvetrain first); milky residue only on the oil cap in a cold, short-trip vehicle, which is often just condensation; and coolant loss that turns out to be a radiator, heater core, or a leaking intake or water pump gasket.
Run a compression test and a cooling system pressure test before ordering anything. Once the diagnosis is confirmed, check our head gasket and 5.7 Hemi listings against your VIN.
Buy the right set the first time
Order a full set, not a pair of head gaskets. Everything you disturb on the way in should be replaced while it is exposed — intake, exhaust, valve covers, coolant crossover and the O-rings that come with the teardown. A complete gasket set costs less than doing the job twice because a five-dollar intake gasket was reused.
Settle these before the box ships:
- Confirm the current part number against the manufacturer catalogue using your VIN, model year and application. The Gen III Hemi ran a long production life across cars, trucks and vans, and the 5.7 changed meaningfully mid-life — cam phasing, MDS content and head casting details are not uniform across the range.
- Head bolts are not reusable. Torque-to-yield hardware is stretched past its elastic limit by design when it is tightened. Reusing it is the most common way a repeat failure gets built into a fresh gasket.
- Studs are a real option, not a default. A head stud kit gives more consistent clamp load and is reusable, and it earns its place on a boosted or high-cylinder-pressure build. On a stock naturally aspirated engine returning to daily service, new factory-specification bolts installed properly are perfectly adequate. Studs also need genuinely clean block threads plus the fastener manufacturer's own torque procedure and lubricant — not the factory bolt figure.
What is different about this engine
| Feature | What it means for this job |
|---|---|
| Aluminium heads, iron block | Different expansion rates; deck flatness and clamp load matter more, and the heads must come off a fully cooled engine |
| Two spark plugs per cylinder | Sixteen plugs to pull, and coil and plug-lead routing to document first |
| Pushrod OHV, cam in block | Pushrods and rocker assemblies come out with the heads; keep every component in its original position |
| MDS on many applications | Deactivating lifters live in specific bores, are not interchangeable with standard lifters, and must go back where they came from |
| Variable cam timing on later builds | Cam timing and phaser handling follow a specific service procedure; do not guess at it |
| MLS-style head gaskets | Multi-layer steel needs a clean, flat, correctly finished deck — it will not conform around damage the way an older composite gasket might |
That MDS row is worth dwelling on. If your engine has cylinder deactivation, the lifters are not all the same part, and a set tipped into one tray and reinstalled at random will run badly at best. Label the bores. The same discipline applies to pushrods, rockers and any valvetrain component that comes out — reinstall wear-mated parts where they wore in.
The sequence, in order
Work cold. An aluminium head pulled off a warm iron block is a warped head.
- Disconnect the battery, relieve fuel pressure and drain the coolant into a clean container. Drain the oil too if coolant has already reached it.
- Document everything. Photograph connector routing, vacuum lines, ground straps and coil leads. Bag and label fasteners by location.
- Strip down to the heads — intake ducting, throttle body, intake manifold, coils and all sixteen plugs, valve covers, exhaust manifolds or headers. Treat exhaust fasteners with respect: manifold bolts on an engine that has heat-cycled for years will snap if you lean on them dry and cold, and penetrant and heat are cheaper than a broken-stud extraction.
- Remove rocker assemblies and pushrods, keeping strict order.
- Loosen the head bolts in the reverse of the factory tightening sequence, in stages, from the outside in. A random order, or one pass, can distort the head.
- Lift the heads off the dowels straight up. Do not lever between head and block deck — a gouged sealing surface turns a gasket job into a machine shop job.
- Inspect and prep. Check the deck and head for flatness with a straightedge and feeler gauge across multiple axes. Clean the surfaces with a method that will not scratch them — no aggressive abrasive discs on aluminium. Chase, do not tap, the block bolt threads, and clear every hole of oil and coolant so the fastener is not hydraulically loading a blind bore.
- Set the new gaskets dry unless the manufacturer instructs otherwise, oriented correctly — most are marked for front and for bank. Confirm the dowels are located and undamaged.
- Torque the head fasteners in the factory sequence, in the specified stages, to the value in the service manual, including any angle stage. On studs, follow the fastener manufacturer's procedure and lubricant instead.
- Reassemble in reverse, new gaskets everywhere, components back in their original positions.
- Refill and bleed the cooling system by the factory procedure. Trapped air will produce a hot spot and undo the repair.
- Fresh oil and filter. If coolant reached the crankcase, change the oil, run it briefly, and change it again.
- Warm it up and watch it. Check for leaks cold and hot, confirm the fans and thermostat cycle correctly, then clear codes and re-scan after a full heat cycle.
An independent shop typically bills this in the range of ten to eighteen labour hours depending on the vehicle and how much of the exhaust hardware fights back. In a home garage with hand tools, plan on a full weekend.
What causes repeat failures
- Reused torque-to-yield bolts. They will not reach the correct clamp load a second time.
- A deck or head never checked for flatness, so an MLS gasket was asked to seal across a warp it cannot bridge.
- Contaminated bolt holes. Oil or coolant trapped in a blind hole gives a false torque reading and can crack the block.
- A cooling system that was never properly bled, producing the same overheat that killed the first gasket.
- The original overheat cause never found. A failed thermostat, collapsed hose, tired water pump or plugged radiator will take out a new gasket as fast as it took out the old one.
Keep the right tools within reach — a calibrated torque wrench, an angle gauge, a straightedge and feeler set, thread chasers and a cooling system fill tool. Our engine tools section covers what this job needs.
Frequently Asked Questions
Can I reuse the head bolts on a 5.7 Hemi? No. The factory head bolts are torque-to-yield: they are intentionally stretched beyond their elastic limit during tightening and will not develop correct clamp load a second time. Replace them with new bolts of the correct specification, or fit a head stud kit.
Do I have to remove the cylinder heads to replace the head gaskets? Yes. There is no in-chassis shortcut. Anyone offering a sealant-in-a-bottle fix for a confirmed head gasket failure on this engine is selling you a delay, not a repair.
Should I use head studs instead of bolts? Studs make sense on a boosted or high-cylinder-pressure build, and they are reusable. For a stock naturally aspirated engine returning to daily service, correctly installed new factory-specification bolts are adequate. If you go to studs, use the stud manufacturer's own torque procedure and lubricant, not the factory bolt figure.
Do the cylinder heads need machining? Check them, always. Any head that ran hot enough to fail a gasket should be checked for flatness and cracks and pressure tested. A light skim to restore the surface finish is common — an MLS gasket will not conform around a surface that is out of specification.
How do I handle MDS lifters during the job? Keep them in strict bore order and reinstall each one in the bore it came from. On applications with cylinder deactivation the lifters are not all the same component, and mixing them up will produce running faults after reassembly.
How long does a 5.7 Hemi head gasket job take? A shop will typically bill ten to eighteen labour hours. Doing it yourself with hand tools, plan for a full weekend and allow contingency for broken exhaust studs.
Sources
Written from Core Powertrain Parts technical staff experience with Gen III Hemi engines, and from standard engine-machining practice for MLS head gaskets and torque-to-yield fastener hardware. Part numbers were checked against our own fitment data at time of writing. Every torque figure, tightening sequence, cam timing procedure and cooling system fill-and-bleed step must come from the factory service manual for your model year and application — those values are deliberately not reproduced here, because they vary across the production run.
Questions on fitment for your year and application: sales@coretransmissionparts.com. Free shipping on orders over $70.