MCC/Smart Roadster/Coupe Crankshaft rear seal/rear main oil leak replacement

Is it important to repair MCC/Smart Roadster/Coupe crankshaft rear seal/rear main oil leaks?

The crankshaft is the main driving force in an internal combustion engine (ICE). If your MCC/Smart Roadster/Coupe is an ICE then it will have a crankshaft and rear seals.

At the bottom of your engine, the crankshaft is working with the pistons and connecting rods to harness the energy of combustion. This energy spins the crankshaft, which provides drive to the transmission and down to the wheels.

It sits low inside the engine block, usually just above the oil pan (also known as the sump) and counterweights splash oil to lubricate the main bearings.

Because the transmission and crankshaft pulley is driven by the crankshaft, a front and rear oil seal are needed to separate the inside and outside of the MCC/Smart Roadster/Coupe's engine.

This seal is usually made up of natural or synthetic rubber and is supplemented by a metal ring on the outside. The seal is held in place by a thin spring which keeps tension on the rubber against the end of the crankshaft.

This keeps the oil in and dirt and debris out. Over time, these seals can perish and start to leak oil. There is no set time replacement interval for these seals, so they need to be replaced when they are leaking.

Time, heat and poor engine oil quality are all factors that contribute to rear main seal failure and once it starts to leak it will need to be replaced. When the seal fails you may notice oil leaking between the engine and transmission, a puddle of oil on the floor/ground and/or low oil level.

A MCC/Smart Roadster/Coupe crankshaft rear seal/rear main oil leak repair includes a lot of labour, as the transmission needs to be removed from the vehicle to allow access to the rear main seal.

If the engine oil has leaked onto the clutch friction material, it should be replaced to minimise the risk of premature failure. Also, oil leaks can mimic a rear main seal leak, such as a sump gasket leak. The correct diagnosis will prevent unnecessary repairs.

Replacing your crankshaft rear seal as soon as it starts leaking will ensure that your MCC/Smart Roadster/Coupe is in safe operating condition and less likely to break down unexpectedly.

If the oil level drops due to a leak, excessive damage to the engine can occur, often leading to a full engine rebuild or needing to replace the vehicle. Clutch damage can also occur due to oil contamination.

When your MCC/Smart Roadster/Coupe crankshaft rear seal develops a leak and needs to be replaced, that’s when your friends from AutoGuru can help!