Mercedes M177 Oil Separator Failure | The Real Cause of Rear Main Seal Leaks
On the Mercedes-AMG M177 engine, failed oil separators can cause excessive crankcase pressure, leading to valve-cover leaks, front crank-seal leaks, and catastrophic rear-main-seal failure. When this happens, repairs can exceed 30 hours of labor and cost well over $10,000. In this video, Mike & Adam at 603 MTech Autowerks breaks down the real cause behind these failures and how to fix them the right way. We cover: • How faulty oil separators create crankcase pressure • Why that pressure forces seals to leak (rear main, valve covers, front crank) • Why we remove the engine for proper repair and inspection • What else to replace while the engine is out — motor mounts, plastic coolant lines, valve-cover gaskets, and front-crank seal Oil separators on your M177 should be inspected at every service. You can even check them yourself , while the engine is running, carefully loosen the oil cap. -If there’s a lot of vacuum and it’s difficult to remove, the separators may be failing. -Do not remove the cap completely; excessive vacuum can affect idle or cause oil to spray. ** It’s best to have a professional technician perform this test — they can confirm the condition safely within seconds. ** Even Mercedes-Benz released LI01.40-P-079518, advising replacement of the rear-main-seal plate/seal and both oil separators together to prevent repeat failures. 🔧 Vehicles Equipped with the M177 Engine: Mercedes-AMG C63 / C63 S (W205) Mercedes-AMG E63 / E63 S (W213) Mercedes-AMG GT / GT S / GT C / GT R (C190 / R190) Mercedes-AMG GLC63 / GLC63 S (X253 / C253) Mercedes-AMG S63 (W222) Mercedes-AMG G63 (W463A / 2019+) Mercedes-AMG GT63 / GT63 S 4-Door (X290) (Some early versions of these engines are more prone to oil separator and rear main seal issues than later revisions.) 🧰 Need your M177 inspected or repaired? If you’re looking to get your M177 engine looked at by us, visit 603mtech.com We have clients transporting their vehicles from across the country for major engine work all the time — and we can even help coordinate transport if needed. 📍 603 MTech Autowerks — New Hampshire’s Mercedes Specialist 🔧 Factory-Trained Technicians | Dealer-Level Diagnostics | Honest Service #MercedesAMG #M177 #OilSeparator #RearMainSeal #MercedesRepair #E63AMG #C63AMG #MTechAutowerks #603BenzTech #WorthTheDrive #MercedesMaintenance #AMGProblems #M177Engine #MercedesOilLeak #AMGRepair #EngineOutService #LI0140P079518
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