What is cylinder head machining and why is it important?

Cylinder head machining resurfaces the head so the gasket has a flat, smooth sealing surface, which restores compression and stops leaks at the head gasket. We remove the head and send it to a machine shop we work with; their charge is listed on your estimate.

What does a valve job involve?

A valve job includes inspecting the valves, seats and guides, grinding or replacing the valves, cutting the seats, and replacing worn guides and valve stem seals. Well-seated valves seal the combustion chamber and restore compression; new guides and stem seals stop oil being drawn past the valves (blue smoke). The machine work is done by a machine shop we work with.

When should I consider cylinder head machining?

Consider it after an overheat or a blown head gasket, or when you see low compression, white smoke or water in the oil. A warped head can be machined flat. The head is pressure-tested first: a cracked head usually has to be replaced, and we tell you before any machining.

Can a valve job improve engine power and efficiency?

It can, when worn or burnt valves were costing compression. Properly seated valves restore compression and smooth running, and power and fuel use usually improve with it.

Do you also inspect cylinder heads for cracks or damage?

Yes. We check the head and the block for warping and visible damage when the head comes off, and the machine shop pressure-tests the head for cracks before any machining.

How long does a cylinder head machining and valve job take?

It depends on the engine and on what the inspection finds. Removing and refitting the heads is a big job on a marine engine, and the machine shop's work and parts add time on top. Your written estimate gives the hours and the expected timeline.

Can this service extend the life of my engine?

It can. A head job restores compression and sealing at the head, but worn rings, bearings or cooling problems still limit how long the engine lasts, so we check the whole engine before recommending it.

Breeze Marine technician inspecting the freshly machined surface of a marine cylinder head

Breeze Marine technician inspecting the freshly machined surface of a marine cylinder head (2)

Cylinder Head Machining & Valve Job

Lost compression? A blown head gasket? You might not need a new engine, just a "top end" rebuild. We remove the cylinder heads, send them to a machine shop for crack testing, resurfacing and a valve job, then refit them and set up the engine to restore compression.

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$150 /hr

Labor estimate Quoted after inspection

Book sends us a ticket; nothing is charged online. Before any work you get a written estimate for labor, parts and the trip fee, and nothing is done without your OK.

Trip fee By distance, one way: $30 in San Pedro, $50 in Long Beach

San Pedro$30
Wilmington, Terminal Island$40
Long Beach: Shoreline, Rainbow Harbor$50
Long Beach Marina, Alamitos Bay$60
Redondo Beach$60
Seal Beach, Huntington Harbour$75
Marina del Rey$85
Newport Beach$110

Farther away: $25 plus $2.50 a mile, one way from our San Pedro shop. No trip fee when the boat comes to our shop, or for plan members. The work of a visit is at least $150; the trip fee is on top.

Registered in California: Breeze Marine Boat Service LLC, San Pedro
Where we work: At your slip from Marina del Rey to Newport Beach, or in our San Pedro shop
Questions first: (213) 693-0224 or submit a ticket

About this service

Top-End Rebuilds

Before You Re-Power,
Consider a Rebuild.

Loss of compression, overheating or a blown head gasket doesn't always mean a new engine. In a top-end rebuild we remove the heads, a machine shop brings them back to the maker's tolerances, and we refit them, often for much less than a new engine.

Resurfacing

Overheating can warp aluminum heads. The machine shop mills the deck surface flat to the maker's specification, so the new head gasket seals tight and holds compression under load.

3-Angle Valve Job

Valves are not just lapped: the machine shop cuts the seats. A multi-angle seat cut gives a good seal and airflow, which restores compression lost to worn or burnt valves.

Pressure Testing

Before you spend money on parts, the machine shop pressure-tests the casting for internal cracks. If the head is cracked, we tell you right away so you don't pay to fix a part that can't be saved.

The Rebuild Protocol.

Cleaning, Machining, Assembling.

Teardown & Clean

We remove the heads and send them to the machine shop, which takes out the valves and springs and cleans the casting (a hot tank for cast iron, aluminum-safe cleaning for aluminum) to remove carbon and scale.

Magnaflux / Test

The machine shop uses magnetic particle inspection (iron) or dye penetrant (aluminum) to look for invisible cracks between the valves.

Machine Work

The deck is milled flat, worn valve guides are replaced and the seats are cut, so the head seals properly again.

Assembly

The head comes back with new valve stem seals (to stop oil smoke), springs set to the correct height and the ports vacuum-tested. We refit it with a new head gasket, torque it to the maker's specification and set up the engine.

Restored Compression.

The heart of your engine, renewed.

Freshly milled cylinder head deck surface

Cylinder head with new valves and springs

Pressure testing a cylinder head for cracks

What We Work On.

From Outboards to Inboard Diesels.

Material Aluminum & Cast Iron

Engines Yamaha, Mercury, Volvo, Yanmar

Tolerance Maker's Flatness Spec

Common Questions

How do I know if I need this?

Symptoms that can call for marine cylinder head repair include overheating at high RPM, white smoke (steam) in the exhaust, water in your oil (milkshake), or low compression in one or more cylinders. The same signs often come from the raw water pump, heat exchanger or exhaust manifolds, so we test first (compression and leak-down) before quoting head work.

Is it worth fixing an old head?

Usually, if the casting isn't cracked. A valve job with cylinder head resurfacing costs much less than a new cylinder head assembly and restores compression and sealing at the head.