When the generator of a car is damaged, the vehicle will stop shortly. Accordingly, the car owner should know how to replace the BMW generator in case of malfunction. Let's consider how to replace the BMW generator using the example of the BMW 3 Series E36.
How to determine if the BMW generator needs replacement: test
First, we will conduct a test that will allow us to check if the generator on the BMW E36 is damaged. To do this, we will check the generator voltage. We will need a voltmeter. It is best to buy a universal meter. It has many useful functions and is very necessary when working with a car.
We connect it under the battery and observe the meter readings while our assistant starts the car. The voltage when starting should not be below 9.5 V. After starting the engine and turning on the lights, the voltage should be between 13.5 and 14.5 V.
Now the person in the car presses the gas pedal and maintains the engine speed at 3000 rpm. The value should not differ by more than 0.4 V compared to the first measurement. In this case, the generator and voltage regulator are functioning properly. If the readings are different, then the BMW E36 generator should be replaced.
Replacing the BMW generator step by step
4-cylinder petrol engine
The first step is to disconnect the negative wire harness of the battery. Now we disassemble the upper part of the air filter together with the airflow meter.
Put the key on the belt tensioner, turn it to be able to remove the V-belt. Then remove the protective cover from the generator current connector. The next step is to unscrew the wire from terminal 30 (connector B +) and terminal 61 (connector D +). If there is a ground wire, i.e., terminal 31, it should also be unscrewed.
Read other useful BMW care tips.
In the versions 316i and 318i, produced from September 1993, it is necessary to disassemble a special roller that is responsible for changing directions. Unscrew the generator mounting bolts and remove it. In later models, only one generator bolt should be removed.
We are going to install the generator. First, we check the bushings responsible for the generator suspension. If they are damaged, they should be replaced.
Now we install the generator in its place and tighten it with screws.
Connect the electrical wires to the generator and tighten the tensioner pulley if present. Put on the V-belt and mount the upper air filter cover. Connect the battery and start the car. For monitoring, you can connect the meter, as was done at the beginning of the article, and check the voltage being supplied.
6-cylinder petrol engine
Start by removing the positive clamp under the hood. People who have not done this before may have trouble locating the battery. If we decide to disconnect the battery clamp, then disconnect the negative one. Now we dismantle the entire air filter along with the airflow meter. The next step is to disassemble the radiator fan.
In models: 320i, 323i, 323ti, 325i, 328i, we must remove the element that allows air to flow around the generator. Then disassemble the latches of the fan cover. They are on the left and right.
We do this with a screwdriver for dowels. Now unscrew the fan blade from the coolant pump hub. For this, we need a flat 32mm wrench. It is worth noting that the nut has a left-hand thread, so it needs to be unscrewed to the right.
When removing it, we recommend pressing the coolant against the pump belt. This will immobilize the hub, making it much easier to unscrew.
It may happen that there is a big problem with removal, then you should hit the key with a hammer. Once we loosen it, we can unscrew it by turning the fan. When using this solution, make sure the fan does not fall to the ground.
Then loosen the clamp and remove the air hose from the generator. Put the key on the tensioner and turn it so that you can remove the V-belt.
Remove the protective cover of the generator current connector and proceed to disconnect the electrical wires. If the grounding wire is connected, we will also disassemble it. We must unscrew the generator mounting bolts, and then we can remove it from the car. Assembly in the BMW E36 with a 6-cylinder petrol engine is similar to the 4-cylinder version.
First, we also check the generator suspension bushings. If we have no objections to their condition, we install the generator in place and tighten the mounting bolts. Then connect the electrical connectors and put on the cover. Put on the V-belt, assemble the oil cartridge, and tighten it securely.
Install the oil hose holder on the generator and tighten the oil hose at the bottom of the filter. We check the engine oil level and top up if necessary.
Install the booster reservoir and coolant. Tighten the boost pressure sensor and the primary exhaust gas valve. Now install the engine underbody shield and connect the grounding wire to the battery.
When it comes to buying a generator, it is better to choose a used one.
Any new generators at low prices are usually cheap Chinese fakes that won't last long.
