Bmw E36 1992 Wiring Diagram

In et 6/10 we looked at what you should expect to repair or replace when buying an E30 BMW 325i. This time, we take a look at the E30's successor, the E36, which was produced between 1992 and '99. From '92-95, the straight six-cylinder engine in the 325i was governed by OBD1 (on-board diagnostics) engine management and was capable of 189hp.

In '96, when the vehicles switched to OBD2, the engine was stroked to 2.8 liters, gaining slightly more torque. At the same time, the M3 3.0 was given a 3.2-liter motor from '96-99, while the 1.8-liter OBD1 318i four-cylinder was stretched to 1.9L as well.

Since horsepower remained the same on all these engines, none of the changes made the cars faster in a drag race, just torquier to drive around town.

While the E36 3-Series is a great car available at cheap prices (you can find a decent M3 under $10k), high-mileage does take its toll. If cared for properly, these cars can last a very long time, and their timing chains means you don't have ever have to worry about broken timing belts.

Our highly-modified Project M3, which sees 7000rpm all the time and puts down over 260whp has 160k miles on the odometer, yet doesn't burn oil, has equal compression on all cylinders, no visible rust and all the electrics are working. A great buy? You bet!

For this guide, we're focusing on the popular 325i/328i, but most of what you see also applies to the 318i and M3. There are a variety of things to watch out for, but thanks to the involvement of the aftermarket industry, the E36 BMW can have a long life, including highly-modified ones.

To help you, we spoke to the experts at Bavarian Autosport (BA), BimmerWorld (BW), BMP Design (BMP), Turner Motorsport (TMS) and UUC Motorwerks (UUC). Their combined knowledge will help you keep a car on the road for many years to come.

Engine
Anybody with an '87 or newer BMW should buy a Peake Research scan tool to diagnose check-engine lights, saving diagnostic bills. It's easy to use and takes seconds to operate.

• The first thing you'll probably hear about from most tuners is the cooling system. While the radiator core is aluminum, the plastic end tanks are prone to crack. BW and UUC sell all-aluminum radiators that should last the life of the car and provide better cooling.

• The water pumps on all OBD1 cars were equipped with plastic impellers that commonly fail. In '96 all OBD2 cars had a longer-lasting metal impeller, but thanks to the aftermarket you can order the robust, high-flow EMP pump through most tuners listed here. We used one on Project M3.

• Cracked plastic water pump pulleys are notorious on high mileage E36s. BMP sells replacement iron pulleys, or you can use lightened underdrive pulleys from BMP, BA, BW, TMS and UUC.

• Over time, rubber coolant hoses become brittle and crack. BW sells Samco silicone replacements as used on Project M3.

• Thermostats commonly fail but BA, BW, BMP and TMS sell low-temp thermostats to help the car run cooler. The housings on OBD1 cars were plastic, so the same companies sell alloy ones that last the life of the car. BW recommends European-spec expansion tanks particularly on hard-driven vehicles. BMP also has brass bleeder screws to replace the plastic ones.

• BA reports the auxiliary fan can often seize. What you can do is remove the wires from the radiator fan temp switch and jump them together to ensure the fan runs with the ignition on.

• Hydraulic valve lifters can become noisy and need replacing around 200,000 miles. You can get them through BMP, BA, TMS and BW. Valve cover gaskets can leak, causing oil to fill the spark plug galleys and cause misfires. BMP, BA, BW and TMS sells replacements.

• Both BW and TMS report the Vanos variable cam timing units become noisy and fail due to incorrect oil change intervals. Aftermarket companies such as Dr Vanos sell rebuilt units for less than the dealer and make them sturdier. As used on Project M3.

• It's been known for the oil pump nut to back out as well. The drop in oil pressure can ruin the motor. An experienced shop can either drill the nut for safety wire, or tack-weld the nut to the shaft. Rally Road sells a pre-drilled nut.

• The ignition key tumbler can become worn, allowing the key to turn without engaging the starter. If you notice this, replace it ASAP or you could be stranded. Additionally, the starter has been known to fail, even on our M3. We replaced it with a remanufactured Bosch unit from BA.

• High mileage cars should obviously have the air filter replaced. Our tuners sell an assortment of high-flow filters to make extra power. Fuel filters also need replacing every 60k miles - a cheap and easy task.

• The rear muffler can lose its silencing effect over time, causing a drone. Obviously there is a large selection of aftermarket stainless units that increase performance, save weight and sound better. See all the tuner's websites.

• The cast-iron exhaust manifolds are prone to cracking. BA and TMS sell "shorty" coated headers that bolt to factory cats and provide better mid-range. For track guys willing to lose cats, BW sells Active Autowerke long-tube headers and BMP has Supersprint long-tube headers for maximum performance.

After 100k miles, the alternator can fail. Our 80amp unit broke at 140k miles but we replaced it with a remanufactured 140amp unit from BA, which fits like stock.

• BA recommended you inspect for loose idler and tensioner pulleys, brittle plastic timing chain guide, plus vacuum leaks from the intake and crankcase vent hoses, boots and elbows. They sell replacements for everything here.

• All high mileage engines can benefit from BA's Lubro Moly Engine Restore Kit; a selection of additives for your oil prior to and after an oil change. We gained 7whp after using it!

Drivetrain
• An E36 can experience driveline shudder caused by a worn driveshaft isolator (AKA guibo) or center support bearing.

• When the clutch needs replacing, BA, BMP, TMS and UUC has a variety of packages with lightweight flywheels.

Suspension
• According to TMS, the front suspension is carried over from the E30 325i, with many interchangeable parts such as control arms and bushings. When front bushings wear, solid rubber E30 bushings are an option. The E30 front control arms are a popular supplement because their outer ball-joints last longer, while the E30 M3 units are aluminum and offer lighter unsprung weight for racers.

• TMS reports the rubber in the suspension generally won't last longer than 50k miles. The rear trailing arm bushings are the worst, giving the car an unsettled feel when they wear; TMS shims will prevent over-extension of the bushings. There are 12 more rubber bushings in the rear alone and these will need to be replaced; they retail for over $700 plus labor.

• TMS reports rear floor and subframe failures on high mileage cars. It starts with a clunking sound but in worst cases the entire rear suspension can fall off the car. So TMS offers reinforcement plates that can be retrofitted to any E36.

• E36 rear shock mounts fail quickly, especially with uprated suspension. The mounts can be upgraded with stronger mounts from BMP, BW and TMS and UUC.

• The front strut towers can deform or crack from either high cornering forces, speed bumps or pot holes. BMW offers reinforcement plates through dealers, or you can order them cheaper through BW, BA, BMP and TMS. Strut tower bars help avoid the problem, and are sold through most tuners. We have UUC's magnesium bar that only weights 2 lb.

• Powerflex urethane bushings from BW upgrade front and rear suspension as well as the differential. They last longer than rubber but retain some comfort. BW also sells complete suspension reinforcement kits.

• UUC has hybrid bearing/bushings designed for both track and street cars. UUC, BMP, BA and TMS also sell urethane bushings.

• Solid bushings are available from TMS but are only recommended for track cars. They provide quicker responses and more feel, eliminating suspension angle changes. They're also better at preventing subframe failures.

• The pressed-metal lower rear control arms are easily bent. However, BW, BMP, TMS and UUC offer sturdy replacements with camber control.

• BA reports cars commonly breaking the pig-tail ends of the rear springs, requiring new replacements or sports upgrades.

Wheels/Brakes
• TMS tells us the 325i started with 15x7'' wheels but you can fit up to 20'' wheels, and even the E92 M3 wheels fit, which is good for racers to know. The aftermarket wheel options for this car are infinite.

• A simple pad upgrade will provide the driver with better stopping power, reports BW. Upgrading to M3 front brakes is another option, costing about $1000 and recommended for track cars. All the tuners have brake upgrades

• For track junkies, UUC has a Wilwood big brake upgrade. Check out this month's Project M3 install.

Body
• As with all older cars, watch for body rust. The E36 tends to rust in the rear wheel arches, according to BA. Look for evidence of rust or bubbling around the edges and above the rear bumper.

Interior
• BA notes that if the heater motor only blows air at high speed, a new resistor is needed on OBD1 cars with dial/slider-type controls. If the blower is erratic on OBD2 cars, a new final stage unit is needed.

• If the power windows and sunroof don't work, the relay (AKA comfort relay) under the left side of the dashboard is the culprit.

• On cars with electric seat that won't recline or tilt, but you hear the motor run, the internal gears are broken. Dealers only offers complete seat frame assemblies with gearboxes, but BA sells repair gears separately.

• The gear shifting mechanism can become sloppy over time, increasing the danger of a missed shift. All tuners listed have quality short-shift kits for a more precise feel, or you can source factory units from BMP or BA. We installed UUC's Evo3 shifter with DSSR selector rod on Project M3.

• When the shift and e-brake boots show signs of wear, Rally Road has cheap perforated and custom leather options.