BMW M3 E46 Buyers Guide


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General Advice

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BMW introduced the E46 M3 in 2000 with the first cars delivered in 2001 powered by a BMW M-Division 3.2L straight six engine. Whilst based on the existing e46 coupe and convertible design, the M3 is a completely different vehicle sharing very few parts with it's regular 3 series siblings. The S54 engine produced 338 BHP and 269 LB/FT, and can propel the M3 from 0-60 mph in 5.1 seconds (manufacturers own figures) (5.5s for the convertible) and onto a limited top speed of 155 mph. Delimited, the M3 is rumoured to have a true top speed of 185+mph and most independent tests indicate a 0-62mph time of 4.8s (which coincidently happens to be the same as the M5 of the same era).

The M3 is a very capable high performance car with great handling. Manual coupes are considered the more desirable drivers car, but SMG-II equipped models offer staggering gear change performance.
Over 16,000 M3's were produced, with most still on the road today. However, with a relatively high perceived cost of ownership, there are plenty of unloved cars for sale so be careful, watch out for poorly maintained examples where services have been missed or shortcuts taken.

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Exhaust

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The standard stainless steel exhaust system was very well designed but has two issues. Firstly, it's heavy, but more importantly, the mild-steel exhaust flanges inevitably corrode and can't be replaced like for like without replacement of the entire exhaust system at a cost of over £1100. However, a satisfactory remedy can be had for just a few pounds using a 66mm C-clamp and 63mm U-Clamp. Alternatively, a enthusiast designed stainless steel split-design flange is now available from £120 offering a permanent high quality solution to this problem.
(see www.ebay.co.uk/itm/111548644687 )

As with the previous E36 M3, Exhaust Hanger failure is common. Look for a slightly lopsided look to the tailpipes and this might indicate one (or more) of the hangers need replaced. The right hand side hanger is most common as only one hanger is present. (There are two on the left hand side). Replacement hangers cost around £40 and are a quick swap with a few spanners and a jack to support the heavy backbox whilst you remove the bracket.

Or... many owners opt to fit a quality aftermarket system which is often sever kg's lighter.

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Engine

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BMW Motorsport 3.2L straight six engine (S54 engine) is very reliable if maintained properly. However, with high dealer servicing costs and relatively complex requirements, many cars have not been maintained to this standard.
Check the service history of the car and most importantly, check any receipts offered.
Firstly, check for the 1200 miles running in service. This service is desirable as BMW used "running in oil" for the bed-in period to allow the engine components to wear and bed in. This service should have been carried out before 1700 at the very latest.
Next ensure all oil services have been carried out on time and Inspection services included all the required elements. In particular, ensure Valve Clearances have been checked and adjusted as this is often overlooked, yet vital to the long term health and ultimate performance of the engine. If in doubt, contact the garage that stamped the log book and ask.

Servicing intervals are adjusted by the ecu based on driving history, and the dash service indicator will request a service at intervals between 7,500 - 15,000 miles.

Typical Dealer Charges:
- Oil Service £169
- Inspection Service 1 £669
- Inspection Service 2 from £899

Common issues:

The OEM Coil Packs can fail, causing single cylinder misfires. All six can be replaced for as little as £120 and are easily swapped over.

Vanos issues are rare but the exhaust hub pins have been known to crack. This can been checked when performing the valve clearance routine during Inspection 2 Service. If a new wheel is required this can cost £400. If the pins have already dislodged, you may need to strip the engine to recover the damaged parts.

Engines have proven to be very reliable so any sign of smoke or oil from the exhaust could indicate a poor service history or very high mileage.

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Gearbox / Clutch

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There was two transmissions available the six speed manual or a sequential manual gearbox (SMG-II). The SMG gearbox is the same as the manual but uses a electro-hydraulic clutch and gear selection unit to allow a simulated automatic mode or high speed sequential changes with either the steering wheel paddles or the gear stick.
The SMG unit is notorious for electrical gremlins, but thankfully many can be solved by cycling the ignition off and on. More seriously, the hydraulic pump can fail and control units can develop faults with replacement costing over £1500.

Depending on how the car has been driven the clutch can last well over 100,000 miles. However, with such performance available, many cars have had harder lives and a replacement clutch will cost from £170 plus fitting. DIY is an option but good access under your vehicle will be required to remove the transmission. (Dealers could charge up to £1100)

Differentials are strong but oil seals are prone to failure. Parts cost only a few pounds, but fitting could take a few hours.
If your diff exhibits a grinding noise when turning sharply when cold, you may require an oil refresh with friction modifier additive added to the diff oil.

Rear end clucks are common and not something to be concerned about.

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Bodywork

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Corrosion is not a common problem with the e46 and if present likely a sign of neglect or accident damage.
A notable exception is around the front and rear wheel arches, The front arches regularly rot from the inside after the galvanised surface wears away as a result of the plastic wheel arch liners rubbing against it. Replacement wings are £200 each and will require professional painting and fitting.
The rear arches gather dirt and salt so need to be kept clean, but also prone to corrosion if the rear bumper rubs against the rear quarter panel.
Regardless of whether your car has signs of corrorision or not, it's worth giving attention to each corner to protect it long term.

A common concern with the E46 M3 is the sub frame cracking away from the chassis. It's not clear how common a problem this is, but there's certainly an issue with the design and it's worth giving attention.
If the car has been driven hard with repeated launches or high torque gear changes, the sudden application of torque through the rear diff can cause failure of the subframe mounting points. This can be very expensive to repair at £1800 ( www.Redish-Motorsport.com ) or £6000 (BMW) for a new floor.
A DIY plate kit is available from Reddish for around £200, but will require a considerable amount of skilled welding and protection and wont include the structural foam that BMW offer as a preventative solution to the problem.

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Interior

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Interiors generally wear well, but the soft Nappa leather needs conditioning and neglected cars will appear tired.

Inner Door Seals and Edge Trims can detach in hot weather, but can be easily reattached with trim tape.

External Door handles can break, but that is caused by a clip coming loose within the door. Seems to occur in hot weather as the plastic expands a little and more common in black cars which attract the heat even more.

The auto dimming rear view mirrors contain a special fluid and over time can leak. If the mirror starts to leak, investigate before the fluid escapes from the mirror unit as it's corrosive and will damage the trim panels around the gear stick area below.
You can replace it with an original costing £400 (Part No B51.16.7.892.264) or with replacement glass dimming unit for around £100 (see Ebay seller Kazza-Tech )

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Electrics

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Alternators are prone to failure and an OEM spec replacement can be around £400 plus fitting, but aftermarket alternatives are readily available from as little as £60 and is an easy DIY task.

LED tail lights added April 2003, a pre 2003 car with the led added will have all the LED's light up when the brakes are on, were a car with LED's as standard the outer LED's will not be brighter when the brakes are on.

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Wheels / Tyres

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The M3 came with 18 inch alloys as standard but there was optional 19 inch wheels and the 19 inch CSL wheels.

E46 M3 Tyre Size 18 Inch
- Front 225/45/18 , Price each £140 - £170
- Rear 255/40 /18 , Price each £150 - £220

E46 M3 Tyre Size 19 Inch
- Front 225/40/19 , Price each £160 - £220
- Rear 255/35 /19 , Price each £160 - £205

E46 M3 CSL Tyre Size 19 Inch
- Front 235/35/19 , Price each £160 - £175
- Rear 265/30/19 , Price each £175 - £220

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Suspension

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Rear springs have been known to crack and replacements cost £185 for OEM springs. Some owners take the opportunity to upgrade all four springs with the Eibach Pro-Kit Lowering Springs (20mm front / 10mm rear) at around £180. This is widely regarded as a worthy upgrade with no loss of ride comfort and improved performance well matched to the OEM dampers.

Suspension bushes, as with all rubber parts, will show their age as well as mileage. Look under the car for signs of cracking on the front wishbone bushes, and front & rear anti-roll bars and prod the rear trailing arm bush for excessive sponginess or a dry, cracked texture. If replacement is required, polyurethane upgrades are available and will outlast and outperform cheaper rubber types.
See Powerflex

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Brakes

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Standard E46 M3 Brakes
-Front 325mm 4 piston front brakes, Pads and discs £360
-Rear 328mm 4 piston rear brakes, Pads and discs £280

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