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Draining Filling Cooling System
 
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Pelican Technical Article:

Draining Filling Cooling System

Nick Czerula

Time:

1 hours1 hrs

Tab:

$60

Talent:

**

Tools:

13mm socket and wrench

Applicable Models:

Volvo V70 (1998-01)
Volvo V70 2.4T (2001)
Volvo V70 AWD (1998-99)
Volvo V70 GLT (1998-00)
Volvo V70 GLT SE (2000)
Volvo V70 R (1998)
Volvo V70 R AWD (1999-00)
Volvo V70 T5 (1998-01)
Volvo V70 X/C (2001)
Volvo V70 X/C AWD (1998-00)
Volvo V70 X/C AWD SE (2000)

Parts Required:

Engine coolant

Hot Tip:

Work with a cool engine

Performance Gain:

Cooling system parts lifespan increased

Complementary Modification:

Replace hoses

Engine coolant is the working fluid for the cooling system, which controls the operational temperature of the engine. Each combustion event inside your engine creates a lot of heat and the engine needs to be at a certain temperature to operate efficiently. Engine coolant maintains about the same temperature year round, regardless of ambient temperature.

A properly maintained cooling system must have a few things in order: adequate supply of coolant, a radiator that acts as a heat exchanger with the outside air, a fan or air flow source, a water pump to keep the coolant circulating, and a thermostat to regulate the engine at its optimum operating temperature. The coolant must also have the correct mixture and chemical compounds to promote heat transfer, protect against freezing, and also inhibit corrosion. To keep your Volvo operating correctly, it's important to check the level, strength, and overall condition of the coolant on a regular basis. You also need to change the coolant before it degrades to the point where it doesn't perform its job adequately.

One failure mode associated with dirty coolant is known as electrolysis. Electrolysis occurs when stray electrical current routes itself through the engine coolant. The electricity is attempting to find the shortest path, and impurities in the coolant often generate a path of least resistance that the electricity travels across. The source of this stray electricity is often from electrical engine accessories, which have not been properly grounded. A missing engine or transmission ground strap can also cause the coolant to become electrified. Sometimes the path of least resistance becomes a radiator, a heater hose, or even the heater core. These components are often well grounded, and offer a ground path from the engine to the chassis by means of the semi-conductive path of the coolant.

Electrolysis can destroy your engine quickly. Although it's semi-normal to have very small amounts of voltage potential in your coolant system, values greater than about a tenth of a volt can start reactions between the coolant and the metal in your engine. In particular, electrolysis affects primarily aluminum engine components, resulting in pitting and scaring of the aluminum surface. This eating away of the metal can cause coolant system leaks, and in particular, radiator leaks around aluminum welds. Cast-iron components are also vulnerable, but typically the aluminum metal parts fail first.

The process works somewhat like electrical discharge machines (EDM). These machines work by passing a large electrical current through metal, literally zapping away bits of material until nothing remains. Unfortunately, the electrolysis process works in a similar way, zapping bits of metal in proportion to the amount of electrical current passing through the coolant. A poorly grounded starter can literally destroy a radiator or head within a matter of weeks, depending upon how often the car is started. A smaller current drain, like an electric cooling fan might slowly erode components over many months.

How can you test for electrolysis? Other than actually seeing visible signs of erosion, you can perform a current flow test. Connect the negative terminal of a voltmeter to the chassis ground. Test for adequate continuity by touching another point on the chassis - the resistance should be near to zero. With the engine cold and running, submerge the positive probe into the coolant tank, making sure that the probe does not touch any metal parts. The voltage should be less than .10 volts. If not, methodically turn off or unplug each electrical accessory until the reading reads below .10 volts. Have an assistant switch accessories (like the A/C compressor, heater blower, etc.) while you measure the voltage.

If an accessory doesn't have an on/off switch, test it by temporarily running a ground from the housing of the accessory to the chassis. Ground each component and check the voltmeter. If the wire restores a missing ground connection to the accessory, then you've found a component with a faulty ground.

During this test, be sure to check the starter. Not only will a poorly grounded starter struggle to turn over the engine, it will also zap away tremendous amounts of metal in your cooling system. Watch the meter carefully when starting the engine. Any voltage spike will indicate a faulty ground connection.

Your Volvo will lose a little bit of coolant here and there over time due to evaporation from the reservoir. However, a significant loss of coolant over a very short period of time almost certainly signifies a leak in the system. Sometimes a leak can be seen when you park the car overnight. Often the coolant leaks out and then evaporates while you're driving, leaving no tell-tale mark of coolant on the pavement. If you suspect a coolant leak, visually inspect all of the hoses, the water pump, the reservoir, and the radiator for seepage or the 'weeping' of coolant out of seams and gaskets. Check the seal on the radiator cap. Check that the radiator cap is fastened securely. The way the Volvo radiator cap is designed makes it easy to make the simple, yet deadly mistake of leaving the cap cocked - allowing coolant to leak out when the engine is running. If you suspect a leak that you cannot see, a pressure test can verify the integrity of your system. See our tech article on cooling system leak testing.

Draining and filling your cooling system is a maintenance requirement as well as being part of many repairs. Be careful when working with coolant. It is poisonous and especially dangerous for pets. Clean all spills immediately and rinse the area with water.

V70 engines hold about 12.5 liters of coolant.

In this article, I'll go over the steps involved with replacing the engine coolant on the Volvo V70 models. Be sure to work with a cool engine and confirm the cooling system lacks pressure before opening the cooling system.

Lift and support the front of the vehicle safely. See our tech article on lifting your vehicle.

Coolant will be filled and the level is checked at the coolant expansion tank also referred to as the reservoir.
Figure 1

Coolant will be filled and the level is checked at the coolant expansion tank also referred to as the reservoir.

Working in the engine compartment, remove the expansion tank cap green arrow).
Figure 2

Working in the engine compartment, remove the expansion tank cap green arrow). Be sure that the engine has cooled before removing the cap. Cover the cap with a rag when opening. If there is still system pressure, this will lessen the spillage.

Place a five-gallon bucket under the left side of the radiator.
Figure 3

Place a five-gallon bucket under the left side of the radiator. Loosen the radiator 13mm drain plug and drain the coolant (inset). Access the drain plug through the hole in the splash shield (red arrow).

Using a 13mm socket, loosen the drain plug.
Figure 4

Using a 13mm socket, loosen the drain plug. I leave the socket on the plug, remove the ratchet and allow it to drain. Allow the coolant to drain into bucket. Once the coolant has stopped dripping, reinstall the radiator drain plug.

Most engines will have a 13mm drain plug (red arrow) on the right side rear of the engine block above the drive axle.
Figure 5

Most engines will have a 13mm drain plug (red arrow) on the right side rear of the engine block above the drive axle. Loosen (inset) the drain plug and drain coolant into the pan.

Using a 50% distilled water 50% engine coolant mix, slowly fill the expansion tank until the coolant level indicator reaches MAX.
Figure 6

Using a 50% distilled water 50% engine coolant mix, slowly fill the expansion tank until the coolant level indicator reaches MAX. The level indicator diagram is located on the tank (red arrows). Reference this when filling to obtain the correct level. 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. Install the expansion tank cap (green arrow). Turn ignition ON (do not start engine), set temperature controls in the vehicle interior to full warm and blower fan speed to Low. Start and run the engine at idle until it reaches operating temperature and check the cooling level, top up as needed. When done, check the cooling system for leaks.

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