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Coolant Flush and Replacement
 
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Pelican Technical Article:

Coolant Flush and Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$25 to $45

Talent:

**

Tools:

19mm, 12mm socket, Philips head screwdriver, large catch tray

Applicable Models:

BMW E10 2002 Coupe/Conv (1967-76)
BMW E21 320i Coupe (1977-83)

Parts Required:

New coolant

Hot Tip:

Get a really big catch tray

Performance Gain:

Proper cooling

Complementary Modification:

New hoses

If you are changing your coolant this is also the perfect time to give your cooling system a complete flush. While it is next to impossible to get all of the coolant and contaminants out of the system without removing the heater core lines and blowing out the heating system, this method will get the system as clean as possible and more than good enough for the next ten years.

A couple of safety precautions/instructions you may want to observe before beginning:

Allow the cooling system to cool down to a coolant temperature of less than 80°C. Open the cap of the cooling system slowly; turn a conventional coolant cap as far as the first detent and turn a screwed coolant cap approximately 1/2 turn and release the pressure. Wear protective gloves, protective clothing and eye protection. NEVER pour coolant into beverage bottles, cups, etc... Someone might accidentally pick that cup up and start to drink. Always dispose of your used coolant correctly and in accordance with your local regulations. Never pour it down a drain or in the ground.

The cooling system on the BMW 2002 is a really simple and basic system to work on.
Figure 1

The cooling system on the BMW 2002 is a really simple and basic system to work on. There is no coolant overflow tank that you need to worry about but that does mean you need to be precise in the filling of the radiator. To drain the system you need to work with the drain plug on the bottom of the radiator (yellow arrow) and the fill/pressure cap on the top (red arrow).

Let the engine cool completely before beginning this job.
Figure 2

Let the engine cool completely before beginning this job. Once everything is cool slowly open the radiator cap to release the pressure. With the cap off the coolant will drain more quickly. If you open this cap while the system is hot and/or under pressure you run a serious risk of harming yourself and the vehicle. Do the smart thing and let the system cool down before beginning.

Place a very large catch tray under the front of the vehicle.
Figure 3

Place a very large catch tray under the front of the vehicle. Remove the drain plug located on the bottom of the radiator. We had the pleasure of working on the Clarion Build's BMW 2002 that had a beautiful aluminum radiator that used a 12mm bolt; make sure to check the drain bolt on your radiator for the correct size socket needed.

The coolant has a tendency to bounce and run off of everything in the front of the vehicle including sway bars and the front valance.
Figure 4

The coolant has a tendency to bounce and run off of everything in the front of the vehicle including sway bars and the front valance. Make sure you have a large enough tray to catch it so you can dispose of it correctly.

Check the condition of your drain plug and check for crush washers.
Figure 5

Check the condition of your drain plug and check for crush washers. The drain plug on our Clarion Build's car was 12mm with a small rubber O-ring; make sure to replace the crush washer if your radiator has one.

If you want to do a complete job remove the block drain plug on the right side of the motor towards the rear of the block (red arrow).
Figure 6

If you want to do a complete job remove the block drain plug on the right side of the motor towards the rear of the block (red arrow). Again be prepared with a large catch tray as the fluid will bounce everywhere once you remove the plug.

If you do not remove the block drain plug there will be fluid trapped in the motor still; use a Philips head screwdriver and remove the upper hose from the head to the thermostat (red arrows) and the lower hose from the thermostat to the water pump (yellow arrows).
Figure 7

If you do not remove the block drain plug there will be fluid trapped in the motor still; use a Philips head screwdriver and remove the upper hose from the head to the thermostat (red arrows) and the lower hose from the thermostat to the water pump (yellow arrows). This will allow gravity to bleed most of the coolant from the engine and radiator.

There is a small hose that goes from the water pump to the heater core.
Figure 8

There is a small hose that goes from the water pump to the heater core. If this hose is not leaking and in good shape just leave it be, as you need to remove the alternator to access the hose (red arrow).

Before just refilling the system take some time and give it a good flush; this will help remove deposits in the block and radiator that will not be removed by a regular drain.
Figure 9

Before just refilling the system take some time and give it a good flush; this will help remove deposits in the block and radiator that will not be removed by a regular drain. While you should use distilled water in your cooling system if you have bought concentrated coolant it is okay to use hose water for a flush. After all, you are flushing the system and the tiny amount of tap water left after the flush will not cause you problems. To flush the radiator remove the top hose, place the radiator cap back on and then place a garden hose into the outlet on the top of the radiator (red arrow). Turn the hose on and flush the radiator until water runs clear out the bottom into the catch tray. You can also remove the lower radiator hose if you want a larger volume of water to flow through.

To flush out the block leave the two thermostat hoses disconnected and remove the hose from the top of the motor by the temperature sensor.
Figure 10

To flush out the block leave the two thermostat hoses disconnected and remove the hose from the top of the motor by the temperature sensor. Pinch off the radiator hose and insert the garden hose into the opening by the temperature sensor (red arrow). Turn on the hose and let it run until the water runs clear out of the water pump and into the catch tray.

To fill the system reattach the hoses and install the drain plug.
Figure 11

To fill the system reattach the hoses and install the drain plug. Premix your coolant if you bought concentrated coolant to the right mixture for your area and climate. Fill the radiator; some people like to squeeze the hoses to assist in getting the air out of the system while it is being filled. Leave the radiator cap off and start the engine. Add coolant if the level drops once you start the motor. Check for leaks. Allow the engine to run with the cap open until it gets hot enough for the thermostat to open. Before the thermostat opens the radiator will bubble up and spill over and then the level will drop. Add coolant as the level drops to keep air from getting in the system. You will be able to see the "current" in the top of the radiator once the coolant is flowing through it. Stop the motor and allow it to cool, and then check the level again. Place the cap back on. Check for leaks, and you are done.


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Comments and Suggestions:
Filip Comments: Just wanted to say; "Thank you for a straight forward and easy to understand tech articles!". Cheers :
July 27, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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Page last updated: Fri 12/9/2016 02:57:35 AM