MAN TGX / TGS EGR Cooler Replacement Guide (51.08100-7204 & 51.08152-5027)

# MAN TGX / TGS EGR Cooler Replacement Guide (51.08100-7204 & 51.08152-5027)

Last Updated: March 2026

---

Summary

The MAN TGX and TGS are the backbone of European and North American long-haul fleets. Both models use the MAN D26 Euro 6 engine, which relies on a high-efficiency EGR (Exhaust Gas Recirculation) system to meet emissions standards. The EGR Cooler — part numbers 51.08100-7204 and 51.08152-5027 — is one of the highest-wear components in this system. Failure typically occurs between 400,000 and 600,000 km, manifesting as coolant loss, white exhaust smoke, or a DTC P0401/P0402 fault code. This guide covers the differences between the two part numbers, how to diagnose EGR Cooler failure on the D26 engine, and the complete replacement procedure including coolant system flush.

---

*MAN D26 Euro 6 engine bay — EGR cooler assembly with blue coolant hoses visible on the left side of the engine block.*

---

OE Part Number Guide

The D26 Euro 6 engine uses two EGR Cooler variants depending on the production year and model:

The 51.08152-5027 is a direct supersession of the 51.08100-7204 for 2018+ vehicles. For pre-2018 vehicles, both part numbers are compatible — the 51.08152-5027 can be used as an upgrade replacement for the older 51.08100-7204.

Cross-Reference Numbers:

---

*Internal cutaway diagram of the MAN TGX EGR Cooler (P/N 51.08100-7204) — blue arrows indicate coolant flow, red arrows indicate exhaust gas flow through the tube bundle.*

---

Common Failure Symptoms

The D26 Euro 6 EGR Cooler fails in three primary modes:

1. Internal Coolant Leak (Most Common)

Exhaust gas pressure causes micro-cracks in the stainless steel tube bundle, allowing coolant to enter the EGR circuit. Symptoms include:

• White or grey smoke from the exhaust, especially at cold start
• Sweet smell from the exhaust (ethylene glycol combustion)
• Coolant level dropping without visible external leaks
• DTC codes: P0401, P0402, P0404, P242F

2. External Coolant Leak

Corrosion or mechanical stress at the coolant inlet/outlet fittings causes external leaks. Symptoms include:

• Visible coolant puddles under the truck
• Coolant staining on the engine block near the EGR system
• Overheating if coolant loss is significant

3. EGR Fouling / Blockage

Carbon buildup inside the cooler reduces heat exchange efficiency. Symptoms include:

• Increased exhaust temperatures
• Reduced engine power (limp mode)
• DTC codes: P0401 (insufficient EGR flow)

---

Diagnosis Procedure

Before replacing the EGR Cooler, confirm the diagnosis:

1. Read fault codes with MAN DAVIE or compatible OBD-II scanner. P0401, P0402, P242F, and P0404 are the primary EGR-related codes on the D26.

2. Inspect coolant reservoir — white residue or oil contamination indicates internal EGR Cooler failure.

3. Pressure test the cooling system — pressurize to 1.4 bar and monitor for 10 minutes. A drop indicates a leak in the EGR Cooler or associated hoses.

4. Inspect EGR valve — remove and inspect for excessive carbon buildup. A blocked valve can cause similar fault codes without cooler failure.

5. Borescope inspection — if available, inspect the EGR Cooler core for visible cracks or deposits.

---

*A certified MAN technician installing a new EGR cooler on a TGX engine — proper torque specification is critical to prevent coolant leaks.*

---

Replacement Procedure

Tools Required: 10mm, 13mm, 17mm sockets; torque wrench; coolant drain pan; MAN D26 service manual

Estimated Time: 3–4 hours

Step 1: Drain the Cooling System

• Allow the engine to cool completely (minimum 2 hours after shutdown)
• Open the coolant drain valve on the radiator bottom tank
• Drain into a clean container for disposal or reuse

Step 2: Remove the Air Intake Duct

• Disconnect the charge air cooler outlet hose from the intake manifold
• Remove the 4× M8 bolts securing the air duct bracket
• Set aside without disconnecting the MAF sensor

Step 3: Disconnect EGR Hoses and Lines

• Clamp and disconnect the coolant inlet hose (upper fitting, 17mm clamp)
• Clamp and disconnect the coolant outlet hose (lower fitting, 17mm clamp)
• Disconnect the EGR gas inlet pipe from the exhaust manifold (3× M10 bolts, 17 Nm)
• Disconnect the EGR gas outlet pipe from the intake manifold (2× M10 bolts, 17 Nm)

Step 4: Remove the EGR Cooler

• Remove the 4× M10 mounting bolts securing the cooler bracket (40 Nm)
• Carefully lift the EGR Cooler assembly out of the engine bay
• Note the orientation of the coolant fittings for reinstallation

Step 5: Install the New EGR Cooler

• Clean all mating surfaces and replace gaskets
• Position the new cooler and hand-tighten all mounting bolts
• Torque mounting bolts to 40 Nm in a cross pattern
• Reconnect EGR gas pipes: 17 Nm for M10 bolts
• Reconnect coolant hoses and secure clamps

Step 6: Refill and Bleed the Cooling System

• Refill with MAN-approved coolant (MAN 324 Type SNF or equivalent OAT coolant)
• Bleed the cooling system using the bleed screw on the thermostat housing
• Run engine to operating temperature and check for leaks
• Top up coolant as needed

Step 7: Clear Fault Codes and Test

• Clear all DTCs with MAN DAVIE or OBD-II scanner
• Perform a DPF regeneration cycle if the DPF has accumulated excess soot
• Test drive for 30 minutes and recheck for fault codes

---

Why OEM-Grade Replacement Matters

The D26 Euro 6 EGR system operates at exhaust temperatures up to 650°C and coolant pressures of 1.4 bar. Budget aftermarket EGR Coolers using 304 stainless steel (vs OEM-spec 316L) are prone to premature failure in this environment. SUMEC's 51.08100-7204 and 51.08152-5027 replacements use 316L stainless steel tube bundles with 0.4mm minimum wall thickness, matching MAN OEM specifications. Each unit is pressure-tested at 45 PSI before shipment.

---

Related SUMEC Products

• [MAN TGX/TGS EGR Cooler 51.08100-7204 (SMC-LQ-164)](/products/man-tgx-tgs-egr-cooler-51081007204)
• [MAN TGX/TGS EGR Cooler 51.08152-5027 (SMC-LQ-165)](/products/man-tgx-tgs-egr-cooler-51081525027)