Cooling System Service: Flushing Kit

The Flushing Kit method of servicing your car's cooling system is another easy and straightforward procedure that comes with handy instructions.

These instructions should be used as only advice. Always follow your car's manufacturer's instructions when servicing it on your own.

Coolant Flush Kit
1. Purchase Your Flush Kit from the store of your choice. A common kit is the Prestone Flush N Fill Kit.
2. Follow the Directions provided with the flushing kit. The following steps are guidelines designed to help clear any ambiguous instructions provided with the kit.
3. Remove the Radiator Cap to release any pressure in the system (make sure the engine is cool before flushing the cooling system!). (Fig. A, see below)
4. Install the 'T' Adapter in the heater core inlet hose. There are two hoses that pass through the firewall (the wall that separates the engine bay from the cabin) on the passenger's side of the vehicle. Follow the hoses to determine which is the inlet and which is the outlet. The inlet hose will come from the engine or thermostat; the outlet will come from the water pump. Find the straightest section of the inlet hose and cut it. Install the 'T' adapter from the kit.
5. Install the Splash Tube in the Radiator where the cap usually goes. Aim the splash tube away from the engine so that the coolant will drain into a suitable container (you can try attaching a hose to help prevent spills).
6. Locate the Radiator Drain, it will probably be on the side of the radiator opposite from the radiator cap, located towards the very bottom of the radiator. (If your car does not have a radiator drain, skip to step 6). (Fig. B, 1=Draincock, 2=Drain)
7. Attach a Hose to the radiator drain, if needed, and route it to a large container capable of holding at least 5 gallons. (Fig. C)
8. Loosen the Draincock to open the drain. Let the old coolant drain out of the radiator (this may take 10-15 minutes depending on the size of the radiator).
9. If Your Vehicle Does Not Have A Radiator Drain or Cap locate the Lower Radiator Hose. This will be a large hose coming out of the bottom of the radiator and then remove the lower radiator hose, being careful to not get antifreeze on yourself. Remove the hose by disengaging the hose clamp with a tool appropriate to the type of clamp used (pliers or screw driver). Route the hose so that it will empty into a large container.
10. Attach the Garden Hose to the 'T' Adapter and turn the water on.
11. Turn Your Heat on High (Fig. D)
12. Start the Engine after water starts coming out of the splash tube.
13. Run the Engine Until it Warms Up, as indicated by the temperature gauge or the radiator fan turning on. Let the engine run for about 10 minutes AFTER it gets to normal operating temperature AND the fluid coming out of the splash tube is clear. (Fig. E)
14. Turn Off the Engine and let it cool down. Then drain the radiator again.
15. Remove the Garden Hose and put the cap on the 'T' Adapter.
16. Fill the Radiator with a 50/50 blend of antifreeze and distilled water. Pour the blend in slowly and use a funnel to help avoid spills. Once the radiator is full, leave the radiator cap off and leave the funnel in place.
17. Burp the Radiator by running the engine again for a few minutes with the radiator cap off. Any air bubbles will eventually find their way to the radiator fill neck and escape with the cap off. During the air's escape, antifreeze can bubble and burp out of the radiator, so keep some rags around and leave the funnel in the radiator to help keep things tidy.
19. Top Off the radiator with your blended 50/50 antifreeze/water.

To summarize:
  1. Install the 'T' Adapter in the heater core inlet hose.
  2. Install the splash tube into the radiator cap opening and drain the radiator.
  3. Attach a garden hose to the 'T' Adapter and run water through the system.
  4. Run the engine until it gets to normal operating temperature, and then for 10 minutes longer.
  5. Shut off the engine and drain the radiator.
  6. Fill the radiator with a 50/50 blend of antifreeze and distilled water.
  7. "Burp" the system by running the engine with the radiator cap off.
  8. Top off the radiator with a 50/50 blend of antifreeze and distilled water.

End Notes
While performing this maintenance, check all the cooling system components for wear and tear. Replace any hoses that show signs of imminent failure, such as cracks, bulges, swelling, or punctures.

After completing this maintenance, your vehicle's cooling system should be ready to perform at its peak for at least a couple of more years!

*ALWAYS make sure you dispose of used antifreeze in accordance to your local laws!

Similar Pages
Here are some links to pages with information relevant to this article.


sleepyfan January 12, 2012 at 1:01 PM  

To the author of this article:

I've been looking for a good set of instructions on how to use the prestone flush kit and was looking for some time now. (maybe 30 min). I lucked into this article and found it far superior to any other instructions. You managed to cover everything precisely and limited the use of car mechanic terminology flies over the head of noobie DYIers. For example, you explained thoroughly what the firewall was while others do not. How the heck am I supposed to know what a car firewall is, I only know the firewall for my computer. Anyway. Thank you for this post! Ive saved this website to my favorites. =)

Jimmy Reeder March 25, 2014 at 1:24 PM  

Thank you for this. It is really hard to find some decent instructions on how to do this online and it’s a good thing your site has this. This will be very helpful to all our friends out there who are looking into doing this by themselves.
Jimmy Reeder

Anonymous,  April 14, 2014 at 12:02 PM  

Hi, I just stumbled across your article while searching for a better understanding of this type of flush kit; The Prestone website is very nebulous on details. I only have one comment/question:
After flushing the system with water, wouldn't you want to refill the radiator with 100% antifreeze/coolant, and not the 50/50 stuff? The engine block would be completely filled with 100% water (which is roughly half of the system's total capacity). Filling the radiator with 100% antifreeze would give you a rough 50/50 mix... Or am I missing something?


David Wilhelm August 6, 2015 at 10:42 PM  

I like the overall instructions but on thing is missing.Once you have drained the radiator by either the drain cock or by removing the lower radiator hose the instructions never mention to close the drain cock or reconnect the lower radiator hose before turning on the water to the garden hose. I know that sounds stupid but some people would follow the instruction to "T"(no pun intended)and never close the drain cock or reconnect the radiator hose.

Stephen Barry May 10, 2016 at 4:17 PM  

These instructions put Prestone's to shame. Hopefully their sleepy staff will take note.

Robert Gilims September 28, 2016 at 12:24 AM  

Nice blog… Thanks for sharing very useful information about Vehicle servicing

John Lee April 10, 2017 at 3:42 AM  

The cooling system removes the tremendous heat generated by your vehicle’s engine. This heat, if left uncontrolled, can quickly damage vital engine components. The cooling system is sealed and under pressure.Your vehicle's cooling system helps cool down important components in the engine bay that heat during operation. If you do not have your vehicle's cooling system serviced on a regular basis, you run the risk of overheating your engine or having a vehicle that won’t start at all due to frozen engine fluids.

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john parelle September 7, 2017 at 2:47 AM  

this article is so wonderful and helpful to me thanks for share.
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