Mercedes AMG M157 M278 Upgraded Rear Coolant Hose & Connector Set
| Brand: | ZEDPERFORMANCE® |
| Product Code: | amg-M157-M278-hose |
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£99.99 VAT incl.
Available Options
Mercedes M157 / M278 Rear Coolant Hose & Connector Set
Two-piece replacement set for the heater hose and coolant feed fitting at the back of the engine. Supplied together, the parts replace A2128302300 and A2782002152 on the E-Class and CLS V8 applications listed below.
The set includes one flexible heater feed hose and one rigid cylinder-head coolant connector. The plastic fittings are PA66-GF30, a nylon reinforced with 30% glass fibre. Mercedes part numbers identify the replacement application; these are ZED Performance aftermarket parts.
Reinforced plastic fittings
The upgraded glass-fibre reinforcement gives PA66 greater stiffness and helps it resist deformation under load compared with unreinforced PA66. That is useful around the hose coupling and mounting points, where the fitting needs to hold its shape.
The PA66-GF30 specification applies to the plastic fittings, not the flexible hose. It identifies the material used in this set; it does not by itself establish a longer service life than every Mercedes OE version.
Replacing the rear connections
When tracing a coolant leak behind the engine, check the hose coupling, rigid fitting and seals. Replacing only the hose leaves the old connector in place. This pair allows both mating components to be renewed together.
If the engine is already out for a rebuild, we recommend replacing ageing rear coolant connections before refitting it. The fitting sits behind the left cylinder head, close to the bulkhead, so access is much easier while the engine is out. A leak here later can mean dismantling surrounding parts to reach a relatively small component.
These parts can also be replaced with the engine installed where the vehicle's repair procedure allows. The rebuild recommendation is about taking advantage of access already available.
Fitment
For the listed M157.981 5.5-litre biturbo and M278.922 4.7-litre biturbo applications. M278 may also appear as 4.6 litres in catalogues. Check that the vehicle requires both replacement references before ordering; an M157 or M278 engine code alone is not enough.
| Model | Body / chassis | Type codes | Approximate production years | Engine |
|---|---|---|---|---|
| E500 / E500 4MATIC | W212 saloon | 212.073, 212.091 | 2011–2015 | M278.922 |
| E500 / E500 4MATIC | S212 estate | 212.273, 212.291 | 2011–2016 | M278.922 |
| E500 | C207 coupé / A207 cabriolet | 207.373, 207.473 | 2011–2016 | M278.922 |
| CLS500 / CLS500 4MATIC | C218 four-door coupé | 218.373, 218.391 | 2011–2017 | M278.922 |
| CLS500 / CLS500 4MATIC | X218 Shooting Brake | 218.973, 218.991 | 2012–2017 | M278.922 |
| E63 AMG 5.5 biturbo | W212 saloon / S212 estate | 212.074, 212.274 | 2011–2016 | M157.981 |
| E63 AMG 4MATIC | W212 saloon / S212 estate | 212.092, 212.292 | 2013–2016 | M157.981 |
| E63 AMG S 4MATIC | W212 saloon / S212 estate | 212.076, 212.276 | 2013–2016 | M157.981 |
| E63 AMG S, rear-wheel drive | S212 estate | 212.275 | 2013–2016 | M157.981 |
| CLS63 AMG 5.5 biturbo | C218 four-door coupé | 218.374 | 2011–2017 | M157.981 |
| CLS63 AMG 4MATIC / S / S 4MATIC | C218 four-door coupé | 218.392, 218.375, 218.376 | 2013–2017 | M157.981 |
| CLS63 AMG 5.5 biturbo | X218 Shooting Brake | 218.974 | 2012–2017 | M157.981 |
| CLS63 AMG 4MATIC / S / S 4MATIC | X218 Shooting Brake | 218.992, 218.975, 218.976 | 2013–2017 | M157.981 |
North American models
| Model | Model years | Engine |
|---|---|---|
| E550 4MATIC saloon — W212 | 2012–2014 | M278.922 |
| E550 coupé / cabriolet — C207 / A207 | 2012–2017 | M278.922 |
| CLS550, rear-wheel drive / 4MATIC — C218 | 2012–2018 | M278.922 |
| E63 AMG, rear-wheel-drive saloon / estate | 2012–2013 | M157.981 |
| E63 AMG 4MATIC saloon | 2014–2015 | M157.981 |
| E63 AMG S 4MATIC saloon / estate | 2014–2016 | M157.981 |
| CLS63 AMG, rear-wheel drive | 2012–2013 | M157.981 |
| CLS63 AMG 4MATIC | 2014 | M157.981 |
| CLS63 AMG S 4MATIC | 2014–2018 | M157.981 |
Years are a guide. Production dates and registration years can differ, and auxiliary-heater equipment, including option code 228, can change the hose arrangement. Confirm both parts against the VIN. This set is not listed for M273 5.5-litre, M156 6.2-litre or later 4.0-litre AMG engines.
Part references and earlier versions
| Component supplied | Replacement reference | Earlier reference |
|---|---|---|
| Heater feed hose | A2128302300 / 2128302300 | A2128302896 / 2128302896 |
| Rear cylinder-head coolant feed connector | A2782002152 / 2782002152 | A2782000831 / 2782000831; A278200083105 / 278200083105 |
Earlier M157 catalogues also show valve references A2782000531 and A2782000631. The later A2782002152 feed fitting differs from the electrically connected valve, so a conversion needs the VIN-specific parts instructions. Check whether connector dust cap A0025457383 is required; it is not one of the two components supplied in this set.
Fitting notes
Inspect the mating surfaces, clips and hose connections before assembly. Renew disturbed seals as required and check for any additional service parts before starting the job.
Pressure-test the cooling system to the Mercedes specification while the rear connection is still accessible. Refill with the specified coolant and follow the vehicle's bleeding procedure before completing the repair.