Flushing The Coolant on a 95 BMW 3 Series
Coolant is a vital part of any engine's cooling system. When it ages or breaks down, overheating becomes more probable and overall system health suffers.
In general, the fluid should be changed at least every 3 or 4 years, but given the age of this car, I recommend doing it more frequently, especially if engine temperatures start to rise.
- 2 gallons of 50/50 premixed coolant
Get the engine warm by driving for 15 minutes. Don't over do it; the goal is to get the coolant warm enough to flow, but cool enough to prevent hazards
Jack the front of the car up. As in all cases, ensure this is done safely and verify that the car is secure before venturing underneath it
Put on safety goggles. Coolant is hot and can spray/steam in random directions
Ready the radiator
Switch the ignition to on, but do not start the engine
Turn on the climate control, set the temperatures to maximum, and switch the vent to warm. This will open the valves fully and allow for maximum drainage
Drain the coolant
Slowly remove the bleeder screw with a phillips screw driver. Steam and coolant may bubble out
Unscrew the large circular cap
Locate the coolant plug. It's on the driver's side sticking out off the inside of the bumper, and is the only thing with a large phillips screw head in the area.
Place the coolant container underneath the plug to collect the old coolant
Slowly unscrew the drain plug with a phillips screw driver. Be careful as coolant is hot
Remove the plug completely and allow the coolant to flow into the container.
As the stream slows down, move the container accordingly to catch all the coolant. Remember what I said about it being hot?
Put the plug back. Do not over tighten, but make sure it is secure.
Add coolant back in
Pour the 50/50 coolant mix into the expansion tank. Use a funnel and do so slowly; coolant is a slippery thing to spill on the garage floor
If the car does not immediately absorb the coolant into the cooling system, run the engine briefly to get it to cycle through.
The coolant should be filled to the Cold (Kalt) line.
Take the car for a short and sweet drive around the neighborhood. Don't push it too hard or go too far in case something went wrong.
Put the heat on full blast and make sure it feels warm.
Check to make sure the A/C blows cold air.
Make sure the engine temperature stays in the center.
If anything goes awry, park it and check the coolant levels. If they've decreased, the cooling system was low and sucked most out of the expansion tank. Nothing to be alarmed about; just add more coolant and try again.
Clean up the garage floor, put away the tools, and give yourself a pat on the back
Take the coolant to a local recycling facility. Most auto shops should be able offer assistance with this. Remember that coolant contains antifreeze, which is hazardous as defined by the EPA.
Check the levels tomorrow
After a night of cooling down, the coolant level may decrease due to a temperature drop. Top her off and you're good to go.
This was one of the easier fixes I did to my E36, and perhaps the most tangible. She never overheats in traffic anymore, and the A/C is much cooler. It will also go a long way in terms of preventative maintenance and extending the life of the vehicle, so that's something to feel good about, too. Time to enjoy another year of the E36 life!