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Freightliner Mt55 Exhaust Gas Recirculation (EGR) Coolers

Freightliner Mt55 Exhaust gas recirculation (egr) coolers

Starting at $684.95, AutoBuffy stocks 2 EGR coolers from Dorman to fit your Freightliner Mt55. The EGR cooler lowers the temperature of exhaust gases before they re-enter the intake, reducing NOx emissions and protecting the engine. A failed cooler can cause coolant loss, white smoke, and engine overheating — ignoring it risks serious engine damage.

Signs your Freightliner Mt55 needs a new EGR cooler

  • White or sweet-smelling smoke from the exhaust, indicating coolant mixing with exhaust gases through a cracked cooler core
  • Unexplained coolant loss with no visible external leak — coolant is being burned through the intake or vented into the exhaust
  • Engine overheating or coolant temperature running consistently higher than normal due to reduced cooling capacity
  • Milky or frothy residue inside the coolant reservoir, a sign of combustion gases contaminating the cooling system
  • EGR-related fault codes such as P0401, P0402, or P0404 stored in the ECU alongside cooling system warnings
  • Rough idle, misfires, or reduced power caused by excessive unmetered coolant vapor entering the combustion chamber

Which EGR cooler should you buy for your Freightliner Mt55?

EGR coolers vary by construction material, internal flow design, and whether they are sold as a bare cooler or as part of a complete assembly with valves and gaskets. Matching the replacement to your Freightliner Mt55's emissions configuration and engine displacement is essential — an incorrect cooler will not seal properly or deliver the right gas-flow volume. Decide first whether you want a direct OE-equivalent unit or an upgraded design that addresses known weaknesses in the original.

OE-Equivalent Replacement
Best for
Drivers who want a straightforward, like-for-like swap that restores factory emissions compliance
What you get
Matched dimensions and flow rate, standard aluminum or stainless tube-and-shell construction, typically includes required gaskets
Heavy-Duty / Upgraded Core
Best for
High-mileage vehicles or engines prone to cooler cracking (e.g., diesel or performance applications)
What you get
Thicker walls, reinforced welds, or improved internal baffling designed to outlast the factory unit under thermal stress
Complete EGR Assembly Kit
Best for
DIYers or shops replacing a cooler that failed alongside the EGR valve or related hardware
What you get
Cooler, EGR valve, coolant hoses or pipes, and all gaskets bundled together — reduces multiple labor visits
Remanufactured Cooler
Best for
Budget-conscious owners who still want a pressure-tested unit with a warranty
What you get
Professionally cleaned and pressure-tested core, often resealed with new O-rings, lower cost than a new unit

Exhaust gas recirculation (egr) coolers brands we stock for your Freightliner Mt55

Dorman
2 options · from $684.95

Replacing the EGR cooler on a Freightliner Mt55

Advanced⏱ 2–4 hoursSocket set with extensions (metric and standard)Torque wrenchCoolant catch basin and coolant flush kitPick tool or seal removal tool for O-rings and gasketsThread-cleaning tap set (recommended for corroded coolant fittings)

EGR cooler replacement on most vehicles requires draining the cooling system, disconnecting coolant lines and exhaust connections, and removing surrounding intake or turbocharger components to gain access. All mating surfaces should be cleaned thoroughly and new gaskets or O-rings used on every connection before reassembly. After installation, refill and bleed the cooling system completely, then run the engine to operating temperature and check for leaks before returning the vehicle to service.

Frequently asked questions

How much does it cost to replace EGR coolers on a Freightliner Mt55?
Parts start at $684.95 on AutoBuffy. Total repair cost depends on whether you DIY or use a shop — professional labor for an EGR cooler replacement is typically several hours of work, since the cooler is often buried behind intake components. Choosing a complete kit can reduce overall cost by avoiding a second labor visit for related parts.
Can I drive my Freightliner Mt55 with a leaking EGR cooler?
No. A leaking EGR cooler allows coolant to enter the intake or exhaust system, which can cause rapid coolant loss, persistent overheating, and combustion chamber damage. Continued driving risks warping the cylinder head or causing a catastrophic engine failure. The vehicle should be repaired before regular use resumes.
What causes an EGR cooler to fail on a Freightliner Mt55?
Thermal cycling is the primary cause — the cooler repeatedly heats and cools with every drive cycle, stressing the internal core over time. Carbon and soot buildup inside the cooler passages restricts flow and accelerates cracking. Coolant neglect, such as running degraded or low coolant, significantly shortens EGR cooler life.
How long does an EGR cooler last on a Freightliner Mt55?
Service life varies widely based on driving patterns, maintenance habits, and engine type. Diesel EGR coolers tend to have shorter average lifespans than gasoline units due to higher soot loads and thermal stress. Regular coolant flushes using the correct coolant specification are the single most effective way to extend EGR cooler life.
Do I need to replace the EGR valve at the same time as the cooler on a Freightliner Mt55?
Not always required, but it is strongly recommended. When the cooler fails, coolant vapor and soot contaminate the EGR valve passages, accelerating valve wear and carbon deposits. Replacing both together during the same labor session saves time and reduces the likelihood of a repeat repair visit within a short mileage window.
Will a bad EGR cooler trigger a check engine light on a Freightliner Mt55?
Yes, in most cases. A failed cooler disrupts exhaust gas flow and temperature readings monitored by the ECU, commonly triggering EGR-related fault codes. A coolant loss code or engine coolant temperature code may also appear. A proper diagnosis with a scan tool will confirm whether the cooler is the root cause before replacement.

Shop exhaust gas recirculation (egr) coolers by year for the Freightliner Mt55

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More parts for your Freightliner Mt55

Engine Oil FilterA/C Refrigerant Discharge HoseComplete Strut SetPower Steering HoseA/C System Seal KitHVAC Pressure SwitchDiesel Exhaust Fluid (DEF) Urea FilterEngine Water Pump

Exhaust gas recirculation (egr) coolers for other Freightliner models

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