How to Fix Coolant in ATV Cylinder

If you discover you have coolant inside your ATV cylinder, don’t take it lightly. ATV engine coolant allowed to stay in the cylinder can damage your engine. Thankfully, you can prevent the damage if you catch the problem early. You will also need to determine the cause of the leak, fix it, and prevent it from happening again. This post will cover all of these points.

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Blown Head Gasket

The head gasket is round, flat, and made of graphite. You’ll find it between your cylinder and cylinder head, where it seals your compression chamber, coolant passages, and oil passages. When it fails, you’ve lost your seal.

If you have discovered ATV coolant in your cylinder, then the gasket “blew” near the coolant passage. When this happens, the piston will suck coolant into the cylinder. You may also notice coolant spraying from your radiator cap or a loose coolant hose as compression gasses build up in the coolant. White smoke and a sweet smell may be present as the engine tries to burn off loose 4 wheeler coolant.

Causes of Head Gasket Failure

Several things can cause head gasket failure. Overheating is the most common culprit. Wear and tear, old coolant, a warped cylinder head, and a frozen engine from a lack of sufficient ATV antifreeze also cause head gaskets to “blow.” They can also just be old. You will need to determine which of these possibilities caused your trouble, or you may have another blown head gasket soon.

Fixing a Blown Head Gasket

Blown head gaskets can only be replaced.

If you want to DIY, you’ll need:

  • a little precision
  • basic tools
  • a quality torque wrench
  • a gasket scraper
  • a new head gasket
  • gasket dressing

You’ll remove the cylinder head. It’s attached with bolts. You may need to remove other parts before you can access your cylinder head. You’ll need to drain the four wheeler coolant on liquid-cooled engines.

Head gaskets notoriously leave bits of head gasket behind when you remove them, so you’ll use the gasket scraper to clean this off. Make sure you don’t scrape anything into the cylinder or cylinder head, and that you don’t scrape hard enough to cause deep scratches that may make the new gasket unable to form a good seal. You’ll apply a little gasket dressing and install the new gasket.

While you have your cylinder head removed, it’s a good idea to reseat your valves and replace your oil stem valve seals.

Make sure you use your owner’s manual to torque your cylinder head bolts correctly and get the engine timing right.

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Loose Cylinder Head Bolts

It is possible that your problem is loose cylinder head bolts. Now, if you feel of them and go, “there’s nothing wrong with these bolts,” you could be mistaken. They only have to be a tiny bit loose, an amount undetectable by a simple twist with your hand, to cause a leak.

Causes of Loose Cylinder Head Bolts

This problem will usually be caused by age, as the movement generated in the engine eventually works them loose, or incorrect torquing.

Fixing Loose Cylinder Head Bolts

You’ll have to replace the gasket because it always has to be replaced when you remove your cylinder head. The steps will be the same as above.

Use your owner’s manual to get the exact tightening specifications and use a torque wrench to match these specifications. You have to get this exactly right, or you’ll have the problem again.

Cylinder Head Fault

Your cylinder head may have hairline cracks or warping that allow ATV coolant to pass into the cylinder.

Causes of Cylinder Head Fault

Both cracks and warping are caused by engine overheating. Warping may also be caused by broken head bolts or improper torquing.

Fixing A Cylinder Head Fault

Cracks can’t be repaired. You’ll need a new engine.

Warping can be repaired, but you can’t DIY.

How to Prevent Coolant Inside ATV Cylinder

You can prevent coolant in ATV cylinder and the potentially scary problem that caused the leak with a few steps.

Take as many steps as necessary to prevent your engine from overheating. This may just require making sure you have enough coolant, buying an aftermarket radiator cap, fan, or coolant overflow tank, or other vehicle upgrades. How much you need to do depends on why your engine is overheating, how hot a climate you live in, and how you ride.

If you ever touch your cylinder head bolts, make sure they are correctly torqued.

Make sure you have 4 wheeler antifreeze and that it is the correct mixture for your vehicle, so your engine doesn’t freeze.

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