In the old days (generally before 2000),
changing your vehicle’s coolant was simple. That procedure is shown in Step 2, below.
After 2000, cars got more complex and many DIYers got
intimidated by the precise filling and “air-bleeding”
procedures required to eliminate
engine air pockets. But don’t worry, it’s easier than it looks. All it takes to get back in
the game is a one-time $83 investment in
an air-powered refilling tool. The details follow in Step 3.
Either way, you can
change your coolant yourself in about an hour. But before you do anything, check your owner’s manual for the recommended procedures and coolant for your car.
Draining and refilling coolant in older cars
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Photo 1: Open drain cock
twisting a quarter
are shown in the next photo.)
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Drain cocks come in several
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Photo 2: Remove the hose
Push together the
clamp spring with
a slip-joint pliers and
slip the clamp away
from the neck. Pull the
hose free and drain
the remaining coolant.
If access is difficult, a
hose clamp pliers
saves time and
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Hose clamp pliers
Hose clamp pliers are available at auto parts stores or online.
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Photo 3: Add coolant
Stir 1 gallon
1 gallon of
together in a
the mix to the
If you're way past due for a
coolant change and your cooling
system is corroded, you should take your car in for a professional
flush. The same is true if
you've mixed different types of coolant in
your radiator. But if you're on schedule for
a coolant change and your coolant is free
of brown, gunky corrosion (extract a little
coolant with a baster to examine it), you
can skip the flush procedure and perform
a simple drain and refill operation yourself
and save money. Here's how:
Start by buying the type of coolant listed
in your owner's manual. If your manual calls for an “extended life” coolant that
isn't available at the auto parts store, buy
it from the dealer. Don't buy a “universal”
coolant. Using the wrong coolant can
cause premature component failure and
void your warranty.
Raise and safely support the front end
of your car on jack stands. Place a large
drain pan under the radiator and remove
the radiator cap. If your radiator doesn't
have a cap, remove the pressure cap from
the coolant tank. Then open the drain
cock and drain the radiator.
Drain cocks come in several different
styles—screw threads, quarter-turn twist,
and quarter turn and pull. Plastic drain cocks become brittle with age and can
break easily, especially if you try to
unscrew a quarter-turn twist style. So, buy
a replacement drain cock at the auto parts
store before you begin the job (they only cost a few dollars; return it if you don't need it).
Then remove the lower radiator hose
clamp and hose from the engine to drain
the rest of the coolant. Use a slip-joint
pliers to remove spring-style clamps. If
you have trouble accessing or releasing the
clamps with a pliers, buy a hose clamp
pliers (see photo). Reconnect and
clamp the radiator hose and reinstall the
drain cock after draining.
Follow the coolant manufacturer's
directions for diluting concentrated
coolant. Mix the coolant and water thoroughly
in a clean bucket. To prevent mineral
deposits on internal engine and radiator
surfaces, always use distilled water—never tap water. Leave the car raised while
you refill the radiator to reduce the possibility
of air pockets forming in the engine.
Slowly fill the radiator or coolant tank
with fresh coolant until the coolant is 1 in.
below the neck of the radiator or a few
inches below the full mark on the coolant
tank. Start the engine and let it run. After
the engine warms, you'll see the coolant
level quickly drop in the radiator/coolant
tank. That means the thermostat has
opened and it's time to add more coolant
to bring the level to the top of the radiator,
or to the “HOT” mark on the coolant
tank. Check your owner's manual or service
manual to see if your car requires a
special air bleeding procedure. Check for
leaks, shut off the engine, install the cap,
lower the car and go for a spin.
Used coolant is toxic waste. Pour it into a screw-cap
plastic container and drop it off at a recycling center.
Sweet-tasting coolant is irresistible to pets—and poisonous.
Just a small amount can be deadly. So soak up any
spills with paper towels or rags immediately if you have
pets wandering around.
Draining and refilling coolant in newer cars
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Photo 1: Remove the lower hose
Slip the pointed end of the removal tool all the way into the end of the hose.
Then pull it around the radiator neck to break the hose loose. Pull it off
quickly and immediately direct the coolant into the drain pan.
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Photo 2: Vacuum-fill the cooling system
Jam the fill tube into the coolant bottle. Then open the valve and let the
vacuum suck fresh coolant into the system. Repeat the procedure until the
system is full.
Changing your coolant yourself, including buying the air-powered refill tool, will save about $50 on your very first coolant change, and about $100 on
each one after that. This procedure works
for any cooling system that’s not contaminated
with rust or oil. We’ll show you how to
check yours and then how to change the
Here’s what you’ll need:
- New coolant (2 gallons)
- Air-powered refill tool (about $85)
- Air compressor
- Hose removal tool (about $4 from auto parts
store or online)
- Shop manual to locate block drain plugs
- Drain pan
- Absorbent paper towels
- Wrenches and screwdrivers
Start by checking the condition of your coolant
when the engine is cool. Remove the radiator
or coolant reservoir cap and examine the
coolant color. If it looks rusty (don’t confuse
orange coolant with rust), has crud or oil
floating on the top, or looks like chocolate
milk, call it quits and take it to a pro. You have
problems that this procedure won’t solve.
If the coolant looks clean, start the job by
jacking up the vehicle and supporting it
with jack stands. Next, place a large drain
pan under the radiator. Loosen the lower
radiator hose clamp with pliers (springtype
clamp) or screwdriver (worm-drive
clamp) and remove the hose (Photo 1). If
the hose won’t budge, use a hose removal
tool (one choice is Tool Aid No. SGT13860
available through our affiliation with amazon.com) to break it loose (Photo 1). Let the radiator and water pump drain
completely. Then reattach the lower radiator
hose and clamp.
Next, locate and remove the block drain
plugs (they’re in a different spot on every
engine, so refer to a repair manual for the
location of yours). Reinstall the block drain
plugs and move on to the refilling step.
Refilling with fresh coolant:
Insert the air tool (we used the UVIEW
550500 AirLift II Economy Cooling System
Refiller; available through our affiliation with amazon.com) into the radiator
neck or overflow bottle. Connect the
exhaust hose and compressed air line and
route the open end of the tool’s exhaust hose
into an empty gallon jug or pail. Then open
the valve and let the vacuum rise until the
needle reaches the edge of the red zone on
the gauge. Then fill with coolant (Photo 2).
The vacuum sucks out any air pockets as it
refills the system. When it’s full, just reinstall
the radiator or overflow tank caps, remove
the jack stands, and go for a spin.
Changing the radiator cap is easy.
Replace the thermostat and radiator cap when you change the coolant
The thermostat is the single most important component in your vehicle’s cooling system because it regulates engine temperature. Yet most owners don’t replace it when they change their coolant. That’s a mistake: A failed thermostat is the second most common cause of engine overheating and engine failure (a failed radiator fan is No. 1). And a worn radiator cap (sometimes it’s on the overflow tank) can also contribute to engine overheating. Both parts are inexpensive (about $12 each at any auto parts store) and are cheap insurance against overheating.
A radiator cap is a snap to change (see photo). It’s just a matter of unscrewing it and replacing it with a new one. Changing a thermostat yourself takes less than an hour (unless it’s buried). To find out how to replace yours, see How to Replace a Thermostat. But if yours is inaccessible, pay a shop to replace it.
Buying the Right Coolant
Most DIYers buy coolant at the
auto parts store because the
label says it’s “universal,”
meaning it works in all cars. The
carmakers disagree. Over the
past several years, they’ve
issued service bulletins warning
that “universal” coolants are
often incompatible with the
newer metal alloys and gaskets
and seals used in their vehicles.
The carmakers aren’t saying
that just to increase sales of
their proprietary coolants.
They’re seeing real (and expensive)
damage caused by these
If you use the wrong coolant,
you won’t see the damage for a
few years. But when you do, it’ll
cost you a bundle. So heed the
manufacturer’s warnings and
buy coolant right from the
dealer. It’ll cost about $6 more
per gallon (most vehicles only
need 2 gallons), but the peace of mind is worth it.