BMW E46 Rod Bearings, Vanos, and Subframe Reinforcement

“The Big 3” on The BMW E46 M3

The BMW E46 M3 with the S54 engine is an incredibly powerful and capable vehicle, but it has some notable points of failure. You will often hear people talk about “The Big 3” when it comes to maintenance on your E46. The Big 3 includes rod bearings, a rebuilt VANOS, and subframe reinforcement.

Coated Rod Bearings

The rod bearings are the biggest vulnerability on the S54 and can severely damage your engine if they fail. The job of the rod bearing is to prevent the rod and the crankshaft from wearing each other out. The bearings are made of a soft metal alloy that wears away when touched, to avoid wearing the crankshaft directly. In most engines, there is a thin layer of oil between the crankshaft and the bearing to reduce this wear. However, the rod bearings on the s54 resulted in a very tight clearance, resulting in a very small film of oil compared to most engines. As a result, there is quite a bit of bearing wear on these engines. And when the bearings fail, it can lead to a total failure of your engine.

To avoid engine failure from rod bearing wear on your BMW S54 engine, it is recommended you replace the rod bearings every 100,000 miles. At 2M Autowerks, we recommend using VAC Motorsports High Performance Coated Rod Bearings to reduce friction and extend the life of your engine. The VAC coated rod bearings add a physical layer that allows you to run the high tolerances in BMW’s while not seeing the typical failures with the OEM part. These bearings are great on the street or the track.

Get your BMW E46 M3 road bearings replaced in San Diego at 2M Autowerks today!

VANOS Replacement

The VANOS, or variable valve timing system used by BMW, is a common place for issues to occur in your E46 M3. The VANOS system is quite complex and there are many points for failure. The VANOS solenoid, camshaft sprocket bolts, exhaust camshaft hub, and the VANOS oil pump are all known to fail on the S54 engine. Symptoms of a failing VANOS can include power loss, hesitation, rough idle, poor fuel efficiency, cold start issues, and SES lights. Worst of all, the tabs on the camshaft hubs can break off and end up in the timing chain, which is bad news for your engine. It is critical to ensure your VANOS unit is properly serviced in your vehicle.

To ensure your VANOS is in the best possible shape, we suggest rebuilding it before it fails. At 2M Autowerks, we can replace your failing VANOS unit with a fully rebuilt unit with factory solenoids and valves from Dr. Vanos. Brand new solenoids alone from BMW can go range upwards of $925. The rebuilt VANOS also comes with high-quality Viton seals for maximum performance and durability. These rebuilt units also come with a 2 year warranty!

Get your BMW E46 M3 VANOS replaced in San Diego at 2M Autowerks today!

Subframe Reinforcement

One of the scariest things to worry about on your E46 M3 is subframe cracks or tears. Even the most babied E46 can suffer from these failures, and it is crucial to get your subframe reinforced. The subframe is what cradles the rear differential, and the rear suspension, brakes, and arms are all attached to this subframe as well. There is a lot of load on the subframe and it is very prone to cracking on these vehicles when the bushings go bad. And if you keep driving with a cracked subframe, eventually sections of the rear floor can rip away.

To avoid these issues, it is highly recommended to reinforce your subframe and replace the bushings to prevent any issues.  Even if your vehicle never leaves the garage, it can still be prone to these issues. We use high quality subframe reinforcement plates to ensure your subframe is strong and will avoid any cracking down the line. We also recommend replacing the OEM bushings with polyurethane ones from PowerFlex. These bushings are meant for performance while not compromising the ride quality of your vehicle by introducing noise or vibration.\

Overall, the rear subframe on the BMW E46 M3 can be a huge issue and we recommend having it be one of the first pieces of maintenance you do on your vehicle. Get your BMW E46 M3 subframe reinforced in San Diego at 2M Autowerks today!