How to Repair a Coolant Reservoir Tank Leak

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The coolant system in your vehicle is an integral part of your engine. It’s a pressurized system that pushes coolant through your radiator as you drive in order to prevent your engine from overheating. When you stop driving and the engine cools, antifreeze, also known as coolant, will remain in your coolant reservoir.

coolant reservoir tank leak


But, a crack in your coolant reservoir can cause a slow leak which could cause your vehicle to overheat the next time you drive. The good news is that this problem is not difficult to diagnose and you should be able to complete the repair yourself if you’re handy with tools.

If you’ve noticed a coolant reservoir leak in your vehicle, have no fear. We’re here discussing exactly how you can fix a coolant reservoir tank leak in one afternoon. Here’s what you’ll need to perform the repair:

  • Automotive epoxy or plastic repair kit (Check Prices Here)
  • Clean rags or towels
  • A siphon
  • A marker pen
  • Pliers
  • An old bucket or milk jug
  • A funnel
  • A new bottle of coolant
  • A radiator pressure tester
  • Safety gloves

How to Repair a Coolant Reservoir Tank Leak (12 Steps)

Fixing the coolant reservoir tank on your vehicle may be easier than removing dirt and grime from the interior of your vehicle. It’s a quick and simple fix that will save you money in costly repairs, like a bad water pump.

Before you start your repairs, contact your local auto parts store to find plastic epoxy. This is what you will use to repair any cracks in your reservoir tank.

1. Detect the Leak

The first step in repairing your coolant reservoir tank leak is to make sure this is where your problem is actually coming from. Leaking antifreeze could also come from worn hoses or the head gasket itself.

You can detect where your leak is coming from by placing a large piece of cardboard below your vehicle’s engine overnight. The location of the leak will be indicated on the cardboard in the morning. Check your vehicle’s manual to ensure the location of the reservoir tank in order to determine where the leak is coming from.

2. Remove Antifreeze from Coolant Reservoir

Once you have detected the leak is coming from your coolant reservoir, you can start by removing the antifreeze from the coolant reservoir with a siphon. It’s important to note that you should never work on your coolant system while the engine is still warm. Make sure that your vehicle has been turned off and allowed to cool before you begin performing this step.

Remove as much coolant from the reservoir as possible with the siphon, you can dump the rest out once you remove the reservoir tank completely.

You can visually check for oil in the coolant reservoir during this point as well.

3. Mark the Leak

Next, you’ll want to determine exactly where the leak is coming from on the reservoir tank. It’s a good idea to mark the area with a black marker so that you can find it easily in later steps. You may also be able to find the location of the leak while you’re draining the coolant in step 2.

4. Remove Radiator Cap

Remember that your coolant system is pressurized. For this reason, you’ll need to remove the radiator cap as you perform this repair.

Don’t forget to make sure your engine is completely cooled before removing this or you could damage your engine, not to mention hurt yourself. The pressure from the radiator can cause the antifreeze to burst out of the radiator if your engine is still warm.

5. Disconnect Overflow Tube and Other Fittings

Now you’re ready to remove the reservoir tank from the engine bay.

Using a pair of pliers, you’ll need to move the clamp along the overflow tube and then twist the tube to remove it from the reservoir tank.

There may be other fittings holding the tank in place so you may need to consult your owner’s manual in order to find each and every one. Once you have removed all of the fittings and the overflow tube, you can remove the reservoir tank.

6. Empty the Reservoir Tank Completely

Next, you can dump the remaining coolant from the reservoir tank into your holding container where you siphoned out the rest. It’s recommended to use a holding container that is disposable such as an old milk jug or clean bucket that you can throw away when you’re done.

7. Wash Reservoir Tank

The last step before you can actually begin your repair is to clean the reservoir tank out completely. You can do this using a water hose to wash the tank inside and out. Allow it to dry out completely. You may need to wait an hour or so before you can begin.

8. Apply Epoxy

Finally, you can mix the epoxy and apply it to your reservoir tank at the location of the leak using an applicator. Make sure to press the epoxy into the crack to completely fill it. Allow the epoxy to set or cure according to the instructions on the package.

9. Replace Reservoir Tank

Once the epoxy has dried, you can replace the tank back into your engine bay. Be sure to replace all of the fittings that you removed when you were taking the coolant reservoir out.

10. Refill Coolant

Use a funnel to replace the coolant from your holding container. You may need to add additional coolant in order to fill the tank to the desired level which should be indicated with a line on your coolant reservoir tank.

11. Radiator Pressure Test

Once you’ve replaced your reservoir tank, you’ll need to reset your coolant system with a radiator pressure tester. You can pick one up at your local auto parts store for about $50.

12.  Monitor for Leaks

The final step is to routinely inspect the repaired area and the overall coolant reservoir for any signs of further leakage. If you notice any additional leaks, it’s usually best to replace the reservoir as soon as possible.

Final Thoughts

It’s important to repair a coolant reservoir tank leak as soon as you detect the leak in order to prevent damage to your engine. If your vehicle is leaking coolant, it will not run optimally once the reservoir gets too low. If your engine overheats, it can cause significant problems such as a blown head gasket which can cost upwards of $1400 to replace.

Bonus Tip:  If your vehicle is under warranty, check with the manufacturer or dealership to see if the reservoir can be replaced under warranty, as repairs might void any warranty coverage!

Save yourself some time and money in the long run and follow these tips for a simple and successful fix to your problem. All you need is a little patience if you don’t mind getting your hands dirty.

When it comes to car repairs, we’ve got you covered. Check out our blog to find more tips and tricks that will keep you on the road and riding in style.

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