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Draining and Filling Cooling System
 
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Pelican Technical Article:

Draining and Filling Cooling System

Nick Czerula

Time:

1 hour1 hr

Tab:

$60 to $85

Talent:

**

Tools:

Set of sockets (13mm could vary), 6mm Allen bit, Flathead and Phillips screwdrivers

Applicable Models:

BMW Z3 Coupe/Conv (1996-02)

Parts Required:

Engine coolant, block drain plug sealing washer

Hot Tip:

Work with a cool engine.

Performance Gain:

Cooling system parts lifespan increased.

Complementary Modification:

Replace coolant hoses

BMW Z3 cooling system components include:

  • Radiator and coolant overflow tank.
  • Belt driven coolant pump bolted to the front of the engine block.
  • Belt driven fan attached to front of coolant pump. Viscous clutch controls fan speed based on engine temperature and rpms.
  • Electric (auxiliary) cooling fan attached to front of radiator. The cooling fan is controlled by the engine control module (ECM) via an output final stage.
  • Electrically heated thermostat.
  • Automatic transmission cooler or heat exchanger (if equipped).
  • Heater valve and heater core (for climate control).
  • Coolant level sensor inside expansion tank.
  • Coolant temperature sensor at cylinder head.
  • Radiator outlet temperature sensor
  • Coolant hoses and lines.

Engine coolant typically consists of a 50%-50% mix of ethylene glycol and water with various additives (example: water pump lubricant). Hot coolant eventually dissolves various internal engine parts, particularly as it ages and mixes with impurities. The manufacturer therefore recommends that you drain and flush the cooling system approximately every two years. Be careful when working with ethylene glycol coolant. It is poisonous and especially dangerous for pets. Clean all spills immediately and rinse the area with water.

Draining and filling your cooling system is not only a maintenance requirement but also a prerequisite of many repairs. Engines used in BMW Z3 4-cylinder models hold about 6.9 liters of ethylene glycol - water mix; Z3 6-cylinder models hold 10.5 liters.

In this article, I'll go over the steps involved with replacing the engine coolant on BMW Z3 models. Be sure to work with a cool engine and confirm the cooling system lacks pressure before opening the radiator or expansion tank cap.

Do not remove the radiator or expansion tank cap or work on any other part of the cooling system while the engine is hot. Coolant or hot steam may escape and will scald you. To do any work on the cooling system, wait until the engine has cooled off.

To avoid marring the paint and trim, work with a plastic prying tool or wrap a screwdriver tip with masking tape before prying out body or interior items.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches. 

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability. 

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Lift and support front of vehicle safely.

Draining cooling system:

Working at top of radiator, loosen coolant expansion tank bleeder screw. See notes below for specific bleeder locations.

Early models: Working at top of radiator, loosen coolant expansion tank bleeder screw. (green arrow)
Figure 1

Early models: Working at top of radiator, loosen coolant expansion tank bleeder screw. (green arrow)

Late models: Working at left rear of engine compartment at coolant expansion tank, loosen coolant expansion tank bleeder screw.
Figure 2

Late models: Working at left rear of engine compartment at coolant expansion tank, loosen coolant expansion tank bleeder screw. (green arrow)


Place a 3 gallon bucket under left side of radiator.

Then remove the splash shield by pulling it straight down and out of radiator support.
Figure 3

Then remove the splash shield by pulling it straight down and out of radiator support.

Working at lower left side of radiator, remove radiator drain plug.
Figure 5

Working at lower left side of radiator, remove radiator drain plug. (green arrows) Allow coolant to drain into bucket. Once coolant has stopped dripping, reinstall radiator drain plug. Place empty 3 gallon bucket under right side of engine, near suspension sway bar. Working at right side of engine block near engine mount bracket, remove engine block drain.

4-cylinder engines will have a 13mm hex block drain plug.
Figure 6

4-cylinder engines will have a 13mm hex block drain plug. (green arrow)

Some 6-cylinder engines will have a 13mm hex block drain plug.
Figure 7

Some 6-cylinder engines will have a 13mm hex block drain plug. (green arrow)

Some 6-cylinder engines will have a 6mm Allen block drain plug.
Figure 8

Some 6-cylinder engines will have a 6mm Allen block drain plug. (green arrow) Allow coolant to drain into bucket. Once coolant has stopped dripping, reinstall block drain plug. Replace block drain plug sealing washer (if equipped). Filling cooling system: Using a 50% distilled water 50% engine coolant mix, slowly fill expansion tank until coolant comes out of expansion tank bleeder screw and reaches MAX COLD.

Early models: Fill until coolant reaches MAX COLD (green arrow) on coolant expansion tank.
Figure 9

Early models: Fill until coolant reaches MAX COLD (green arrow) on coolant expansion tank.

Late models: Fill until red indicating float reaches MAX COLD (green arrow).
Figure 10

Late models: Fill until red indicating float reaches MAX COLD (green arrow).

Bleeding cooling system:

Trapped air is common when filling a cooling system and can result in improper cooling. It is important to bleed your cooling system each time the cooling system is serviced. Working at top of radiator, loosen coolant expansion tank bleeder screw. Turn ignition ON (do not start engine), set temperature controls in vehicle interior to full warm and blower fan speed to Low. Slowly fill expansion tank until coolant coming out of expansion tank bleeder screw is free of bubbles. Once coolant is free of bubbles, tighten expansion tank bleeder screw. Start and run engine at idle until it reaches operating temperature. Shut engine OFF and allow it to cool. Check coolant level in expansion tank. Top up coolant until level indicator is at MAX. Once at MAX, your cooling system is full. Min and Max levels are embossed on coolant expansion tank for reference. Install engine splash shield and check cooling system for leaks.
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Comments and Suggestions:
Eli Comments: do you have it in stock
November 13, 2016
  Followup from the Pelican Staff: I have no way of checking parts. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 

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Page last updated: Mon 12/5/2016 02:06:55 AM