How do you clean a heat exchanger or aftercooler?

We remove the cooler, take off the end caps, soak the core in a descaling solution to dissolve scale and salt, and rod and brush the tubes we can reach. Then we flush and neutralize it, reassemble it with new seals and pressure-test it to the maker's specification before it goes back on.

How often should I clean my heat exchanger or aftercooler?

In saltwater we suggest a yearly check of the coolers (end caps, zinc anodes, tube ends) and a full cleaning and pressure test about every 3 to 5 years or 1,000 hours, or sooner if the engine starts running hot. Where your engine maker's schedule is stricter, follow it.

Can cleaning damage an old cooler?

Not a sound one. Descaling removes scale without scraping, but on an old core the scale sometimes hides thin or pitted tubes, and cleaning can expose a leak that was already there. That is why every cooler is pressure-tested after cleaning, and we tell you if a core needs replacing.

Can cleaning the coolers lower my engine's temperature?

Often, yes. Removing scale and deposits restores water flow and heat transfer, so an engine that ran hot because of scaled coolers runs cooler again.

Is this service suitable for both inboard and outboard engines?

This service is for engines with closed (freshwater) cooling and charge-air coolers: diesel and gas inboards, sterndrives with closed cooling and generators, including their oil and gear coolers. Most outboards are cooled directly by raw water and have no heat exchanger or aftercooler, so they need a flush instead.

How long does the cooler service take?

Usually 4-8 hours of labor, depending on how many coolers the engine has, how easy they are to reach and how much scale has built up. The descaling soak itself takes several hours, and every cooler is pressure-tested before it goes back on.

Can regular cleaning extend the life of my heat exchanger and aftercooler?

It helps. Regular cleaning, fresh zinc anodes and new seals slow corrosion and keep blockages from building up, but a core that is already thin or pitted still has to be replaced.

A Breeze Marine technician wearing safety glasses

A Breeze Marine technician wearing safety glasses (2)

Heat Exchanger & Aftercooler Cleaning

A clogged cooling system spells trouble for marine diesels. We remove the heat exchanger and coolers, clear the scale and deposits that cut cooling capacity, and pressure-test each cooler before it goes back on.

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$150 /hr

Labor estimate Usually 4–8 hours

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: Call us or submit a ticket

About this service

Engine Cooling

Clean Coolers. Cooler Engine.

Marine cooling systems fail from the inside out. In a raw water cooling system, salt, scale, and growth build up inside the coolers where you can't see them. We take the coolers apart, descale them and remove the deposits that cut cooling capacity.

Chemical Descaling

We soak the core in a descaling solution that dissolves scale and salt, including in places a rod or brush cannot reach, then rod and brush the straight tubes.

The Aftercooler Risk

Aftercooler failure can be catastrophic. If the core corrodes through, seawater can leak into the intake air and reach the cylinders. Regular cleaning and pressure testing are essential preventative maintenance that helps you avoid a major boat diesel repair.

Pressure Proof

Cleaning is only half the job. After cleaning, every cooler is reassembled with new seals and pressure-tested to the maker's specification before it goes back on the engine.

Our Process.

Cooler service, step by step.

Disassembly & Triage

We carefully remove end caps and extract the core bundle. We inspect for obvious erosion, electrolysis, or physical damage before cleaning begins.

Descaling Soak

The core soaks in a descaling solution for several hours to break down calcium scale and salt, and we rod or brush the tubes that can be reached.

Flush & Neutralize

The core is removed and flushed with fresh water to remove loosened debris, then dipped in a neutralizing agent to protect the metal.

Pressure Test & Paint

We reassemble with new O-rings and pressure test the unit. Once passed, the exterior housing is cleaned and repainted engine color.

The Unseen Difference.

Restoring efficiency you can't see from the outside.

Brass heat exchanger core before and after cleaning

Hydrostatic pressure testing a heat exchanger

What We Clean.

We service these marine coolers.

Components Heat Exchangers, Aftercoolers, Oil Coolers, Gear Coolers

Materials Copper-Nickel (CuNi), Brass, Bronze, Aluminum

Testing Pressure Test to the Maker's Specification

Common Questions

Why not just "rod out" the tubes?

Rodding only clears the straight seawater tubes. It misses the complex air fins on aftercoolers and the tight oil passages on oil coolers. Soaking the whole core in a cleaning solution reaches every surface, inside and out, so we do both.

How often should this be done?

For marine diesels in saltwater, manufacturer recommendations vary, but generally every 3-5 years or 1,000 hours is essential preventative maintenance.

Stop Overheating.

Get your coolers cleaned and pressure-tested.

Schedule Cooler Service

Aftercooler Cleaning for Marine Diesels

A descaling soak reaches the parts of an aftercooler core that rodding cannot: the complex air fins and tight passages where salt and scale collect. A failed aftercooler can let seawater into the engine's intake, so the core needs to be clean and pressure-tested before it goes back on.

An aftercooler clean follows our full process: disassembly and inspection, several hours in a descaling soak, a fresh water flush and neutralizing dip, then reassembly with new O-rings and a pressure test before the housing is repainted. For marine diesels in saltwater, this service is generally due every 3 to 5 years or 1,000 hours, so let us know your engine model, when the coolers were last serviced and whether a marine diesel engine overhaul is planned.

Signs your coolers need cleaning

A marine diesel that runs hotter than normal at cruise, loses power or smokes more than usual may have scaled or blocked coolers, a common cause of boat engine overheating. Milky oil or oil in the coolant can point to a leaking oil cooler, and seawater in the intake is a sign of aftercooler failure.

Oil cooler cleaning, like heat exchanger and aftercooler service, is best done as preventative maintenance before these signs appear.