Practical Automotive Maintenance: Flushing & Bleeding The Coolant System

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Flushing & Bleeding The Coolant System

04.26

00:00	In this module we're going to take a look at the finer points of flushing and bleeding a cooling system.
00:05	Which is a crucial maintenance procedure that removes old coolant, debris and air pockets from the system, ensuring optimal engine temperature regulation and preventing overheating.
00:15	Let's now run through the process of changing our coolant and then bleeding the system step by step.
00:20	If you don't need to change your coolant and are only looking to bleed up your system, feel free to skip to the second step.
00:26	Firstly, it's always best if we can locate the car's service manual and check the factory recommended procedure whenever possible.
00:33	Before getting into the job itself, let's first make sure that the engine is completely cool and that we have all the tools and PPE we're going to need.
00:41	That means a system flush product, coolant that's specific to our vehicle, a funnel, a container for the old coolant, as well as gloves and goggles.
00:49	Some vehicles may also require a jack and axle stands or a vacuum coolant filler.
00:54	Which we covered in the cooling system section of this course.
00:57	First we need to locate the radiator and the coolant reservoir.
01:01	Clean the area around the radiator cap to prevent debris from entering the system and then place a large drain pan or container under the radiator drain valve or a lower radiator hose.
01:12	Open the radiator cap and the coolant reservoir cap to allow air into the system.
01:16	Open the radiator drain valve and remove the lower radiator hose to drain the old coolant.
01:21	Collecting all the coolant for proper disposal.
01:24	Once fully drained we can then close the valve and reattach the hose.
01:28	Step two involves flushing the system, but only if we need to.
01:32	This might be necessary if the existing coolant is contaminated, the wrong type has been used or the system has overheating or sludge issues.
01:40	This requires filling the system with distilled water and a cooling system flush product according to the manufacturer's instructions.
01:47	Replacing the radiator cap and starting the engine we can now run it for 15 minutes with the heater on maximum to circulate the flush solution.
01:55	Then after allowing the engine to cool completely we can drain the flush solution.
02:00	This process can then be repeated again if needed to ensure any remaining debris has been removed from the system.
02:06	Now, we can move on to step three which is to fill the system with the correct type and amount of coolant for the vehicle and begin the bleeding process.
02:13	Depending on our particular application this may be a simple case of filling from the radiator cap itself until completely full and then letting the engine run with the heater on maximum.
02:23	We can then add coolant as needed until the level stabilizes and no air bubbles are visible.
02:28	This is often the case with older cars, but as we've already discussed more modern vehicles tend not to be, so simple.
02:35	This could mean jacking up the rear of the car in the case of a mid or rear engine vehicle or locating factory bleed ports found at the highest points in the cooling system.
02:44	By opening these we can ensure that all the remaining air is removed then the coolant is topped up and the ports are closed back up.
02:51	If there's ever any doubt about the location or amount of these ports it's always a good idea to consult the factory service manual or search online.
02:58	In many cases this still isn't going to cut it and now's the time to break out the vacuum coolant filler to fill the system and ensure that there are no remaining pockets of air.
03:08	Don't stress if you're not familiar with this tool because we're going to dive deeper into the finer details of how to use it in the next module.
03:14	With the cooling system now filled and fully bled we can jump into the fourth and final step which involves replacing the radiator and reservoir caps and then running the car, checking for leaks and monitoring the coolant level over the next few days of driving.
03:28	And remember we should always dispose of old coolant properly as it's toxic to animals and the environment.
03:34	Many parts stores and service centres will accept used coolant for recycling.
03:38	Let's quickly run back over the main steps in this process before finishing up.
03:42	To flush and bleed the cooling system, start by draining all the old fluid.
03:46	With the engine completely cool, place a drain pan under the radiator, open the caps and drain through the valve or the lower hose before sealing it again.
03:54	If required, flush the system with distilled water and a flush product, run the engine with the heater on high, then let it cool, then drain, repeating if needed.
04:04	Next refill with the correct coolant and bleed the system, either through the radiator cap, bleed ports, raising the vehicle or using a vacuum filler, making sure all the air pockets are removed.
04:15	Finally, refit the caps, run the engine to check for leaks and monitor the coolant level over the next few days, disposing of old coolant safely.