BMW E30 325i - Bimmer Buyer's Guide Part 1

Have you ever seen an old, yet clean little BMW E30 325i on the road and thought to yourself it would be a great daily driver? These cars have a bulletproof reputation and plenty of old-school style to keep them looking fresh. With the cars dating back to 1986, there are some cheap examples out there, and you can easily run them for several more years with proper maintenance. However, just because it bears the Bavarian badge, doesn't mean you won't have parts to replace or things to look out for.

We contacted our BMW tuning and maintenance friends at Bavarian Autosport, BimmerWorld, Turner Motorsport and UUC Motorwerks to exploit their intimate knowledge of what commonly goes wrong and the best way to fix them.

This month, we start with the 1986-1991 E30 325i, and hope to cover the E36, E46 and E90 in future issues. Obviously, there are other E30 models but we wanted to choose the most popular model, and many of the tips provided here apply equally to all models.

What we've highlighted here will help you know what to look for when purchasing an E30 325i, or help you to keep yours on the road for longer. However, the specialists listed here also sell aftermarket parts to make the 325i faster and handle better. They have everything from suspension systems to big brake kits, ECU chips, exhaust and cams. Call them or visit their websites (listed below) for more details.

Sloppy gear shifts can be overhauled with stock replacement parts or upgrades such as this UUC short shifter kit

Sloppy gear shifts can be overhauled with stock replacement parts or upgrades such as this

Engine
2.5-liter inline-six cylinder M20B25
• As an interference engine (meaning that if the timing belt breaks, the pistons will bend the valves), it's imperative the M20's timing belt and tensioner must be changed every 60k miles or every four years. It takes about three hours and $35 in parts. While you're at it, check the water pump for play, and fit a new ignition rotor and cap - these are easy replacements at this point.
• To reduce valvetrain wear, valves should ideally be adjusted every 15k miles. Rocker arms can crack over time at high RPM when valves are improperly adjusted.
• The airflow meter flap can cause driving issues if not portioned properly. It needs to be tuned back to spec.
• Gunk can often accumulate in the idle stabilization valve, causing a rough idle. Remove it and flush with brake cleaner. Other drivability issues can stem from a leaking intake boot, brake booster hose, idle valve hose or vacuum lines, so check them all.
• Quality fluids are a no-brainer. Use Lubro Moly, Redline or similar, preferably 15w-50.
• Check the cooling system by allowing the car to idle for 10min with the A/C on. Watch the temperature needle and listen for the auxiliary fan to come on to keep the engine cool. If the fan is seized, remove the wires from the radiator fan temperature switch and touch them together to see if the fan runs. If it doesn't, the fan's broken, if it does, replace the sensor. A low-temperature radiator control switch is recommended.
• The stock radiator's plastic end tanks can crack with age. A good upgrade is an all-aluminum unit with quality coolant. Bav Auto also carries Evan's waterless coolant we use in Project M3.
• An overheated M20 engine will never run right because the alloy cylinder head will warp and crack. A compression test is a good idea for any car you might be considering.