How To Use A Radiator Flush Kit With Pictures and Videos

By | April 5, 2023

How To Use A Radiator Flush Kit With Pictures and Videos
Flushing a radiator is an easy task for the DIY Backyard Mechanic.

Precaution should be taken mainly that the engine must be cold.

Never open a radiator cap on a hot engine as it will have built up pressure that could explode out possibly causing injury.

Since radiator fluid is damaging to the environment be sure to dispose of it properly.

Also, be sure not to leave open buckets of radiator fluid around pets, as it is poison to them and they may try to drink it.

Tools Needed for Flushing a Coolant System

How To Use A Radiator Flush Kit Tools Needed

  • Screwdriver
  • Utility Knife
  • A Standard Garden Hose
  • Antifreeze

A flush kit will be needed in this example we are using the popular Preston Kit.

Antifreeze is also needed when refilling the vehicle with fluid.

Locate the Inlet Heater Hose

How To Use A Radiator Flush Kit Locate The Heater Hose
Two hoses go to the heater core through the firewall. The Inlet hose is used to flush the radiator.

One hose lets fluid flow in (Inlet) and one hose lets fluid flow out.

Sometimes they are marked on the firewall. If there is no marking follow the hoses, the Inlet hose will go to the top of the engine. The Outlet hose will go to the bottom of the water pump.

Connecting a Coolant Flush Kit

A T-Unit will be in the kit and is connected at the Inlet hose.
Installing a Coolant Flush Kit
A flush kit comes with different sized T-units to match the Inlet hose on your vehicle.

Cut the Inlet hose so that the T-unit can be centered into it.
How To Use A Radiator Flush Kit Installation

Slide the hose clamps onto both ends.
How To Use A Radiator Flush Kit Hose Clamps

Insert the T-Unit into both ends of the hose.
Installation of a Radiator Flush Kit

Center the T-Unit so it points up and tighten the hose clamps.
How To Use A Radiator Flush Kit Tighten  Hose Clamps

A cap is included in the kit that screws on after the radiator has been flushed.
How To Use A Radiator Flush Kit CAP

Using the Kit Coolant Flush Kit

Take a garden hose and connect it to the top of the T-Unit.
Using A Coolant Flush Kit

The radiator cap is where fluid will come out. Use the attachments to feed the old coolant into a bucket.
How To Do A Radiator Flush 2016

Turn the garden hose ON to start flushing the vehicles coolant system.

Start the vehicle and set the heater to High.

The old fluid will begin to run out. Five minutes of flushing is good for most cars and trucks.
Let the systm flush  for five minutes

Refill the vehicle coolant system and close it up.

The above is a basic step-by-step guide to using a flush kit to clean up a car or trucks coolant system and radiator.

Always remember to use safety precautions when doing any mechanical work.

Since the location of parts on vehicles often defer it is a good idea to get a manual on your car or truck for a quick reference.

Category: General Automotive Repair

About Bob Thomas

Bob Thomas is an automotive mechanic with 30 plus years experience. He is a contributor to several publications and has written many articles on automotive maintenance and repairs. He also has created many auto repair videos on YouTube.

5 thoughts on “How To Use A Radiator Flush Kit With Pictures and Videos

  1. Leonard Taylor

    This was,a lot, of help,thank to all of your information,I have a lot of problems,with my 1995,chevy 1500, 4.3,Lt,anyway thank again.

  2. Frank Wesser


    I’m dealing with a used 2001 Dodge Durango that had engine replaced(180,000 miles on it) and replaced by professional mechanic with used engine (115,000 miles).

    Engine runs great with tune up etc. I had the engine coolant flushed twice by Quik Lube and rust still in system. I used Zerex and Preston’s flush solutions and after numerous flush rinses the coolant is gone but rusty water still appears. It seems like maybe clearing but not really. My next move was to drain engine block but drain plugs hard to remove even with beaker bars.

    I’m thinking about buying the Preston’s flush kit and installing, but I feel like I’ll be doing what I already did repeatedly: fill up distilled water, start engine and heat up to open thermostat , heater in full blast, and run throughout system , drain and repeat .

    What will the kit do to better rid system of rust?

    1. TXSed8R

      I had the same problem with a 1985 K5 Blazer. 200,000+ miles. Full of rust. I read a ton of info and what worked best was to drain the radiator, fill it with 1 gallon of white vinegar and top it off with water. Idle with radiator cap off and keep filling with water until full. Put cap back on and drive for about a week. Then I used this flush kit as directed here. It cleared out decades of rust and got it super clean. You can repeat this process if needed, but mine was cleared out after doing this once. The vinegar is safe on all of the coolant system components and transforms the rust into a liquid to be flushed out.

  3. Jeff

    Ok so it is flushed out. Now haw do you refill the system with the right mix of antifreeze. After the hose is removed the system would be full of water. You need a 50/50 mix of antifreeze here in the Northeast or you will have a freeze up.

  4. Vince

    According to the kit instructions, calculate how much concentrated antifreeze you need based on the system capacity and pour it into radiator with the flush cap off. The antifreeze will displace the water, forcing it out the T fitting. Then run the engine a bit and top off the overflow reservoir afterwards


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