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How to Change Your Engine Coolant

Over time, engine coolant loses its anticorrosive properties and lubricating ability. Some carmakers recommend changing the coolant every 30,000 miles. The recommended change intervals vary widely, however, so check the maintenance schedule in your owner’s manual.

engine coolantFamily Handyman
Over time, engine coolant loses its anticorrosive properties and lubricating ability. Some carmakers recommend changing the coolant every 30,000 miles. The recommended change intervals vary widely, however, so check the maintenance schedule in your owner's manual.

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engine coolant Family Handyman

You can change your coolant yourself in about an hour. You’ll need to invest in an air-powered refilling tool to remove air pockets from the cooling system as you fill. You’ll save about $50 on your 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. I’ll show you how to check yours and then how to change coolant.

Here’s what you’ll need in order to know how to change coolant:

  • Coolant (2 gallons; about $40)
  • Air-powered refill tool ($90)
  • Air compressor
  • Hose removal tool ($8 at auto parts store or online)
  • Shop manual to locate block drain plugs
  • Drain pan and paper towels
  • Wrenches and screwdrivers

To begin, check the condition of your coolant when the engine is cool. Remove the radiator or coolant reservoir cap and examine the coolant. 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 (spring-type clamp) or a screwdriver (worm-drive clamp) and remove the hose. If the hose won’t budge, use a hose removal tool (one choice is Tool Aid No. SGT13860; about $7 online) to break it loose. 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 not in the same 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.

Refill with fresh coolant

Insert the air-powered refilling tool (we used the UView 550500 AirLift II Economy Cooling System Refiller; $90 online) 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. 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.

Buying the right engine coolant

Most DIYers buy coolant at the auto parts store, which carries a product labeled “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 coolants.

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 need 2 gallons), but the peace of mind is worth it.

1. Remove the lower hose

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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. Then pull it off quickly and immediately direct the coolant into the drain pan.

2. Vacuum-fill the cooling system

engine coolantFamily Handyman

Insert 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.

Click here to check out another article on how to change coolant.

Plus: 36 DIY Car Detailing Tips