Mandatory: E46 M3 Maintenance

Like all sports cars, the E46 M3 comes with a few problem areas. Some are minor and some are very serious like VANOS failures and subframe splits. If you’re considering to buy an E46 M3 or currently an owner, these are all the items you should know about and expect to take care if you have not already. Check out this section to take care of all E46 M3 maintenance that is mandatory. All suggested parts listed here are recommendations and you will need to research if you’re trying to diagnose your issue.

Rod Bearings

Problem: Excess heat and friction will cause your S54 rod bearings to wear overtime and at about 100k miles you should really look into replacing your rod bearings. There are some additives you can add to limit the wear, but it’s only short term. We did a full write up on treating your engine with Liqui Moly MoS2 with oil sample tests in case you’re curious. In the long run, you want to replace. BMW did create a service action recall to fix this premature issue, but still only short term.

Solution: Replace OEM rod bearings with WPC treated rod bearings.

Parts: ECS WPC Treated Genuine BMW Rod Bearings – Full Set – $495.95

VANOS Rebuild

Problem: There are multiple issues associated with the S54 VANOS unit. VANOS solenoid solder connection disconnects, cam bolts become lose and snap inside the engine, worn down oil pump disc, VANOS hub tabs break and gets tossed into the engine, VANOS piston seal o-ring deteriorates, and chain guide wears down. If you’re having timing issues or hear abnormal ticking coming from the solenoid, you definitely want to consider doing a VANOS overhaul. Some get lucky, but when the metal hub tab breaks off it’ll most likely go into your engine causing major damage.

Solution: Do a Beisan Systems VANOS overhaul. Please make sure to do some research on what parts you need for the S54 overhaul.

Parts: Beisan Systems S54 Solutions

VANOS High Pressure Oil Line

Problem: The S54 VANOS oil line creates up to 1,200 psi in the feed line and the neck area closest to the banjo bolt on the solenoid tends to crack or burst. The VANOS high pressure oil is used to maintain responsive and accurate camshaft adjustments. Failure in this line can do serious damage to your engine.

Solution: Replace OEM line with new updated BMW high pressure oil line or aftermarket high pressure oil line.

Parts: ECS S54 Exact-Fit Stainless Steel Vanos Line – $68.95

Subframe/Chassis Reinforcement Kit

Problem: The rear mounting points for the subframe can rip out in the sheet metal caused by excessive torsion load from the differential to the chassis. We’ve literally seen a chassis split in half!

Solution: The better of the two solution is to weld metal plates on the problem areas with kits provided by Turner, Bimmerworld, Redish Motorsport, VAC, HPF, and Achilles to name a few. The other solution was an epoxy method serviced by BMW as a recall, however welding is a more “permanent” fix although it is not 100% guaranteed.

Parts: Turner Motorsport Rear Subframe/Chassis Reinforcement Kit – $129.95

Constant Pressure Valve (CPV)

Problem: The CPV has an o-ring that tends to flatten and harden over time because of excessive heat which causes a leak in the line. The valve is located behind the exhaust manifolds which makes it a must-replace job if you’re taking out the headers for whatever reason.

Solution: High temperature o-ring. Replacement of the valve takes about 1.5 hours or about 5 minutes when the headers are off.

Part: ECS Heavy duty Constant Pressure Valve O-Ring – $5.95

Radiator

Problem: The OEM radiator has plastic end tanks which are prone to crack caused by high-low temperatures. Coolant temperatures can reach up to 207 degrees under normal operating conditions and quite possibly higher during track days. Plastic expands in heat and contracts in cooler conditions so it’s just a matter of time until your OEM end tanks leak!

Solution: Replace with an all aluminum radiator.

Parts: CSF High Performance Radiator, Turner/Fluidyne Radiator Upgrade.

Radiator Hose

Problem: The OEM coolant/radiator hose gets brittle and cracks overtime leading to leaks. Just like the radiator issue above, hot-cold temperatures will prematurely wear out the OEM material. If you’re upgrading your radiator to all aluminum, you might as well spend the extra $80 to upgrade your hose kit.

Solution: Replace upper and lower OEM radiator hose with a silicone radiator hose kit.

Parts: ECS Silicone Hose Kit – $123.95



Differential Bolts

Problem: Excessive torsion load may cause stock differential bolts to snap. Even when you accelerate and decelerate, the drivetrain load causes force and adds stress on the differential bolts. Now, go out to the track where you put the car in a more severe environment, you might want to really consider replacing bolts. $12 for a pair is worth it.

Solution: Replace with updated BMW-part-number differential bolts.

Part: Transmission Mounting Bolt M12x50 – $5.09



Rear Shock Mounts

Problem: There have been many reports on M3Forum on the rear shock mounts blowing out of the washer and causing a bit of damage to the shocks. If you hear squeaking, rattling, or clunking it may be a sign that the RSM is going bad. Monitor around 60,000 miles.

Solution: Replace OEM rear shock mounts with aftermarket reinforced and redesigned mounts.

Parts: E46 M3 Rear Shock Mounts



Rear Trail Arm Bushings (RTAB)

Problem: Premature wear of OEM bushing can result in poor handling, excessive tire wear, and alignment issues. In some cases, members on M3Forum have reported premature bushing wear at ~40,000 miles of daily driving.

Solution: Replace with OEM + RTAB Limiter Kit, Delrin, Monoball or polyurethane bushings. Delrin or polyurethane can cause bind on your multi-lateral suspension causing more damage to your parts. A lot of people recommend using rubber RTAB with a Limiter Kit or monoball.

Part: E46 M3 Rear Trail Arm Bushing



Front Shock Tower Reinforcement Plate

Problem: When using aftermarket camber plates, the front strut tower may began to deform or crack when driving in “poor road conditions” due to uneven distribution of pressure.

Solution: Install BMW Upper Strut Mount Reinforcement Plates on each tower.

Parts: Front Upper Strut Mount Reinforcement Plate – $11.28

Rear Spring Perch Reinforcement Plate

Problem: The aluminum cast construction of the lower arm, only on the E46, may cause the spring perch to deform or crack. Similar to the strut tower reinforcement, the uneven load from an aftermarket spring perch may cause improper seating thus damaging the suspension. This applies if you have after market height adjusters.

Solution: Install Rear Spring Perch Reinforcement plates.

Parts: Rogue Engineering Rear Spring Perch Reinforcement Plates.

Shoutout to Obioban for the tremendous E46 M3 maintenance guidance and help from the M3Forum community and Bimmerzone for the maintenance I and II information.