The E46 M3 is considered the last analog M3 and is still used today as the benchmark quintessential sports car. With a celebrated history, massive enthusiast community, and astounding aftermarket support, it has maintained relevance and still commands a premium price, even for SMG-equipped examples. Despite all those positives, and the 333bhp S54 power plant under the hood, they do suffer from some common issues. Fortunately, those issues are well documented by now and the solutions are readily available, but they are issues all the same. This article will help you understand what you might expect as a new E46 M3 owner or if your M3 is climbing to higher mileage as you enjoy it.
If you are looking for an E46 M3, you’ve probably heard about the rod bearing issue. In short, BMW did not spec the rod bearing sizes correctly, which causes premature wear and eventual failure. Unfortunately, the solution is effectively 100k mile rod bearing service. That’s the part most owners and enthusiasts tend to forget. The rod bearing service, while critical, isn’t a permanent solution. Even the best options, like our WPC Treated Rod Bearing Service Kit, for your E46 M3 isn’t a lifetime part. While they may last longer than the 100k mile interval outlined by BMW’s technical service bulletin update, a 100k mile service is imperative to keep your S54 happy and healthy. It is definitely something you need to look for if you are purchasing an E46 M3, but note the mileage. If the service happened at 50k miles, and your potential car has 90k miles, you’ll still need to do those rod bearings in roughly 60k miles.
VANOS Camshaft Hubs
VANOS, or basically BMW Vtech, is the variable valve timing system BMW uses to adjust cam and valve timing across the RPM range. VANOS units are a known issue for all BMWs of this era, but the S54 has a unique twist. It is important to perform the VANOS service if you suspect your VANOS is failing, but it is also critical that you ensure the VAC updated VANOS camshaft hubs are included in that service. In simple terms, tabs on the camshaft hubs have a tendency to break off and find themselves in the timing chain, which can spell disaster for your engine. Stay ahead of this catastrophe with our BMW E46 M3 Dual VANOS service kit and VAC camshaft hubs.
While most modern cars, or even cars of the same era as the E46, don’t require this kind of service, the S54 is a different breed. A ‘drawback’ of the high-revving engine is that the lifters were designed similarly to older racing engines that use shims to set engagement points with the valves for correct operation. It is recommended that a valve adjustment is performed roughly every 60k miles to prevent any valves from falling outside of their operational tolerance. You’ll need feeler gauges and shims for this job, much like the old racing engines from the DTM glory days. Our Valve Adjustment Kit has everything you need.
Gaskets/Front Main Seal/Rear Main Seal/Clutch
We wouldn’t call this a ‘common problem’ so much as maintenance must-dos. You will likely encounter one or more leaks on the aging S54 and will want to address them immediately. The most common oil leaks are from the oil filter housing, VANOS oil line, the front main seal, oil pan, and rear main seal. All the gaskets except the rear main seal are relatively accessible. Our Exact-Fit stainless steel VANOS line is a perfect upgrade that tackles that concern, but for the rear main seal, you have a bit more work cut out for you. Since the transmission will need to come out, it’s best to go ahead and replace your clutch at the same time with a new clutch kit. Both the manual and SMG versions use the same parts. We have handy gasket kits put together for the valve cover gasket and rear main seal, crankshaft, and oil pan gasket that will get you started. A clutch kit will finish the job.
For you SMG owners, the SMG pump was once a dreaded failure. It is common for the SMG pump to fail, which renders your E46 M3 useless. Back in the day, that meant shelling out several thousand dollars for a full SMG unit. Now, the physical mechanism itself is available separately, making this a few hundred dollars rather than thousands. The SMG pump is something you should address unless you see that your example has had a recent replacement prior to your ownership.
Perhaps the most worrying and trickiest problem to diagnose is the dreaded subframe cracks or tears. Even cars that have never seen more than standard street driving can suffer from this engineering oversight and should be inspected before purchase and periodically. However, when we say hard to diagnose, we mean that it is physically a lot of work. Pre-purchase inspections generally just include a visual inspection of the mounting points on the chassis without removing the rear subframe. Unfortunately, the subframe bushings can hide fissures and cracks that can be fatal to your E46 M3 you might need to worry about even if it ‘passed’ its PPI. Without removing the subframe entirely, you won’t know for sure. Regardless, the Turner Motorsport Rear Subframe Reinforcement Kit is a permanent fix that will help you keep your intact or repaired subframe stout and reliable until the end of time. Just remember, even if your E46 M3 doesn’t look like it has subframe cracks, there could still be cracks hiding under the subframe mounts.
Ok, this is less of a common problem and more of a handy trick to save some money. If you have a ZCP (competition package) E46 M3 with the 345mm brake rotors, you’re looking at several thousand bucks every time you need to do a complete brake service. Our enthusiast owner expert recommends using the non-competition package brake rotors as ‘burners’ or ‘track day rotors’ since you have a wider variety of aftermarket options at much lower cost available. You will need different caliper carriers and everything, but it’s a one time expense that will save you money in the long run, especially if you spend time at the track. If you don’t have a ZCP E46 M3, no worries. But if you do, and don’t want to spend the money on rotors after a few track days, use the non-competition package brakes and you’ll be just fine. Here are our solutions for E46 M3 brake service kits.
Naturally, all the regular maintenance like fluids, filters, spark plugs, coil packs, brake pads, and regular services are needed to keep your E46 M3 in check. However, this list details all the big-ticket items that are common failures and not considered ‘regular maintenance’ you need to know before jumping behind the wheel of perhaps the best M-car ever designed. With help from your friends at ECS Tuning, you have all the parts and resources you need to bring your E46 M3 back up to snuff and ready to enjoy for years to come.