How to flush transmission fluid out of cooling system

If you’ve ever had to replace your transmission fluid, you know that getting it all the way out of the cooling system can be a challenge. In this blog post, we’ll show you how to do it quickly and easily. We’ll also discuss some of the benefits of flushing the transmission fluid out of the cooling system.

How to flush transmission fluid out of cooling system

What is Transmission Fluid

How to flush transmission fluid out of cooling system

Transmission fluid is a liquid that transfers energy from the engine to gears inside a car. It also helps cool the transmission and reduces friction between parts in a car’s automatic transmission.

Transmission Fluid Function

The cooling system circulates water throughout the engine to keep it cool. The radiator, which is filled with pressurized air bubbles, sits at the front of the vehicle and removes heat from the liquid as it flows through. When it reaches the radiator, heat from the liquid causes some of the pressurized air bubbles to expand and form steam bubbles. The steam itself cannot flow out of its own accord so it rises to exit through an overflow pipe in the top of the radiator – this room for more liquid to enter the radiator is provided by a layer of air trapped underneath the steam. The cooled liquid from the radiator then flows back to the engine where it absorbs heat, and starts heating up again as it travels toward the front of the vehicle. At the end of its journey through the cooling system, it returns to a reservoir at an optimal temperature to once again absorb heat from inside the engine block – this time being used for transportation rather than being removed from circulation.

How Transmission Fluid Cooling System Works

The transmission fluid cooling system, which includes both parts of a car’s automatic transmission and parts of a car’s cooling system, uses much hotter water than normal to operate. By connecting these two systems together via an auxiliary, fluid from each one can be circulated through the other. In this case, coolant from the car’s cooling system is used to fill a part inside the automatic transmission called a torque converter where it absorbs heat from the transmission fluid inside it. When this happens, some of its own water droplets are heated up and converted into steam bubbles. The hot water then circulates back into the engine block to remove more heat, and then returns to circulate in a similar way as a normal automatic transmission.

When do you flush Transmission Fluid

It is important to flush transmission fluid out of the cooling system if the transmission has been worked on. If not flushed, this transmission fluid will contaminate the new or refurbished one. This can lead to costly repairs down line.

There are two ways you can empty the old fluid from your radiator:

  • By purchasing an automatic transmission flusher (about $30 at an auto parts store)
  • Using gravity by filling up the radiator with new fluid and then running it for about 3 minutes (adapted from tips provided by Les Stanford Chevrolet)

If you do not remove the old Transmission Fluid during a proper transmission flush, you run the risk of ruining your new tranny. Removing old Transmission Fluid is always good practice before replacing your transmission.

How does ATF fluid increase fuel economy?

There are some types of automatic transmissions that require the use of special fluids which allow for improved mileage. These vehicles may have a sticker or marking on them letting you know what type of fluid is required. The most common types are called DEXRON, MERCON, and MERCON V. These can be found at your local car parts store. Another less common but still popular type being used today is called SUPER-TEX (aka Syntorq). This product has been around for many years and it’s probably the older stuff still floating around in peoples trunks and garages from before they realized their old ATF could replace this newer ‘synthetic’ stuff. If you don’t choose the correct fluid then you can expect a significant decrease in fuel economy.

An example of how this works is that many automatic transmissions have ‘pumps’ that pressurizes the fluid inside to help shift gears. If your old ATF is already dirty and contaminated with sludge, water, or metal shavings from the bearings it can cause extra resistance on these pumps which will lead to increased pressure which leads to higher temperatures. In turn higher temps lead to more friction within the transmission causing lower MPG’s. A new filter and fresh clean fluid along with improved shifting will usually result in restored efficiency. This improvement depends mostly on what type of quality control has been employed in manufacturing that particular automatic transmission however since most cars today are using high quality well balanced parts you can expect to see at least a 10% improvement in mileage.

Why ATF Wears Out

How to flush transmission fluid out of cooling system

As transmissions wear, they lose fluid level. This loss of fluid is the single-most risky condition an automatic transmission can face, since it’s a direct risk to the continued function and life of the transmission.

It’s also extremely dangerous and in most states illegal to drive on with inadequate or no transmission fluid (specifically in question: automatic transmission fluid).

If you’re hearing a whining noise from your trans while driving slow at light throttle – you are likely experiencing worn gears. If this is happening after replacing your oil pan gasket – you are likely suffering from ATF leakage for one reason or another.

There are several reasons why ATF losses its viscosity, but here’s an easy way to flush out your cooling system completely, remove the ATF, and get it back in there fresh.

Note that ATF has a very high detergent content, and that’s its main purpose – to clean the inside of your transmission. It also lubricates gears but it doesn’t have near enough additives to remove metal shavings or anything like that – if you’re experiencing any problems with gear wear, this is not the way to fix them.

Atf Fluid Types

How to flush transmission fluid out of cooling system

When an ATF fluid type is mentioned, the three types available are Dexron IIE, Dexron III and Mercon. They are generally not interchangeable because each has its own specific properties.

  • Dexron IIE is a universal ATF fluid which works in both non-particulate manual transmissions and older torque converter automatics designed for Type F fluid.
  • Dexron III is a newer and improved universal ATF fluid that works in both older and newer torque-converter automatic transmissions and non-particulate manual transmissions.
  • Mercon is the only ATF fluid type recommended for use by Ford Motor Company automobiles. It can be used in all type A, B, and H automatic transmissions as well as in non-particulate manual transmissions.

You may need to flush transmission fluid out of the cooling system if you have recently replaced your ATF fluid or had a repair kit installed. The best way to do this is to first drain the radiator and refill with water only (not coolant). Then drive the vehicle until the temperature gauge reaches the half-way mark. Repeat this entire process two more times. By doing this you are flushing out any remaining ATF fluid through both the radiator and engine block. It is important to keep in mind that Dexron IIE, III or Mercon ATF fluids must never be used for this purpose because they are not compatible with coolant.

ATF Fluid Types which should not be used for this purpose include Type F,Toyota Type T-IV and GM DEXRON VI. These ATF fluids must not be combined with coolant.

Another option is to drive the vehicle until it has reached normal operating temperature, allow it to cool and drain the oil. Refill with fresh, clean ATF fluid only (no more than one container) and drive it for another 50 miles. Then change the ATF fluid immediately before putting on a new filter.

How to flush The transmission Fluid  Yourself

How to flush transmission fluid out of cooling system

Flushing out your transmission fluid is very important if you are trying to keep the longevity of it. Having too much metal in your fluid can clog up your pump and other vital parts of The transmission, so getting rid of this excess metal is very beneficial.

Mechanic shops charge upwards of $100 for flushing your transmission fluid. This is a service most people will only go to the shop for because of the cost and time it takes to do it. However, there is another option: doing it yourself. Flushing out your transmission fluid yourself does require some knowledge and equipment, but once you have that there won’t be any reason why you can’t do this job at home.

Step 1.

First you’ll need a few things: a transmission fluid catch container, a large oil drain pan or bucket, gloves and a funnel. You can buy a kit with everything included for under $20 at most automotive stores. The kit will come with instructions on how to do it as well, so make sure you read those thoroughly.

Step 2.

The first step is to drain the fluid out of your car. To do this you will need to locate the transmission dipstick, which should be on the driver’s side in most cars. Slowly pull It out and if it is covered in fluid wipe off any excess so that only dry stick is showing in the tube. Place a catch container under the stick and slowly place it back down, allowing all of the fluid to empty into the container.

Step 3.

You can now start flushing out your transmission fluid. Start by pouring a generous amount of the old transmission fluid from your catch container into your new oil drain pan or bucket. If you bought a transmission flush kit this is where you would add the included fluid. Make sure to pour slowly so that you get every bit of old fluid from the catch container into the oil pan or bucket.

Step 4.

Once you have poured all of the old transmission fluid from your car into the drain pan, continue pouring in a couple quarts of new transmission fluid through a funnel until there is no more spilling out. Next start your car and let it run for thirty seconds before shutting off the engine again.

Step 5.

Once your engine is turned off, remove the funnel from the drain pan or bucket and place a new catch container under the transmission fluid dipstick. Slowly pull It out one last time to ensure you get every bit of old fluid out of the tube. You are now done with the flushing process.

Step 6.

The next step is to fill up your transmission again using new fluid. Place a funnel into the engine’s dipstick tube and pour in another couple quarts (or until it starts spilling out the top). Start the car back up for another thirty seconds then turn off the engine once more.

Step 7.

Before you place your car up to speed, check the transmission fluid level one last time. If it is below the “LOW” mark slowly pour in some new fluid until it is back to where it needs to be. Once this happens you are done flushing out your transmission fluid and your car is ready to go for another couple thousand miles before needing another fluid change.

Flushing out your transmission fluid is something that needs to be done every so often when you are trying keep the longevity of your car’s transmission. This is a job can be very difficult if you don’t know how to do it, but once you get past the initial fear it isn’t that difficult.

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