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How to Inspect Your Car’s Coolant Hoses and Junctions [VIDEO]

August 21, 2019 Even the best coolant hoses in today's modern cars have weak points. Usually found at the junctions and bends in the hoses, leaks and cracks can happen. But do you know how to inspect your coolant hoses properly? Auto technician The Humble Mechanic shows you how to perform some simple inspections and… Allstate
engine hoses

Even the best coolant hoses in today’s modern cars have weak points. Usually found at the junctions and bends in the hoses, leaks and cracks can happen. But do you know how to inspect your coolant hoses properly? Auto technician The Humble Mechanic shows you how to perform some simple inspections and safely identify any needed repairs.

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Hey everyone, its Charles from, and today I’m going to give you some tips on inspecting your coolant hoses.

In a modern car the quality of coolant hose is actually better than it’s ever been. But that doesn’t mean they aren’t free of problems. Today, I’m going to show you a few things to look at and give you some tips on inspecting your own coolant hoses.

Before doing this inspection, we need to make sure we keep safety in mind. We want to make sure we’re doing these inspections with the vehicle cold. When the vehicles hot, the cooling system is under pressure. If we have a weak point and happen to touch it, that could rupture and cause serious injuries. So remember, when we’re doing this or any other inspection or repair, we want to keep safety in mind.

You also want to make sure that you never open the coolant reservoir or radiator cap on a hot vehicle. Coolant hoses will be found throughout the entire engine compartment. There will be multiple connections at the radiator, on the front of the vehicle. There will be connections at the bulkhead near the back of the engine compartment that go to the heater core, and there may be several junctions going into and coming out of the engine and or transmission.

Most modern cars have different materials when it comes to coolant lines. You have these soft formed hoses, as well as composite hoses. And normally, when a problem arises with a coolant hose, it’s somewhere near these junction points. I always like to start off with focusing on the composite, or plastic like material, of the coolant junctions.

The heating and cooling cycles of these parts can make them weak so we’re going to start our inspection by looking for any cracks any discoloration or any oil on these composite parts. And if we see an issue we want to get it taken care of right away. You also want to be extremely careful if you’re touching the plastic parts, because these are usually the easiest things to break.

Now, when it comes to inspecting the soft hoses, there’s a couple of things that we want to look for. First thing we want to look for is any degradation caused by the coolant, and that’s when the hose will deteriorate from the inside out causing a problem. This may not cause an external leak, but may result in a bulge in the hose, or a soft spot, or what might feel like a gap in the hose. You can check this by squeezing the hose and feeling for that soft spot or gap. This often happens anywhere from 1 to 3 inches from a junction point.

Next we’re going to look for leaks. This is probably one of the more common things to see. This can result from a failure of the hose, as well as a failure of the junction point, or simply a loose clamp. If the junction has a clamp, start by checking that first and making sure it’s tight. Tightening up that clamp may stop the leak altogether.

Next we’re going to look for any cracking or dry routing of the hoses. This is where you’ll see micro cracks on the exterior of the hose. Sometimes getting a flashlight and looking really close at the hose is the best way to see this. The most common place for this failure is where hose curves, bends, or has a very strict routing.

Next we want to look for any damage caused by something rubbing on the hose. Perhaps during a repair a hose was not routed properly or another component wasn’t repaired properly. This can lead to a hose rubbing on something like a fan, a belt, or another pulley under the engine. This is most often caused by collision damage or an improper repair.

And finally oil contamination — this is the one that I see most often. This is where we have an oil leak that’ll leak down onto a coolant hose. As you can see here the host swells up really big; the oil reacts with the hose and actually weakens it causing it to swell. Even with proper clamping force, this can cause coolant to bypass the clamp and leak. Now we have an oil leak that needs to be repaired as well as a coolant leak.

Now when it comes to checking for a coolant leak there’s a couple of methods you can use. You can do a simple visual inspection and look for the leak, keeping in mind that coolant and all other fluids will leak from the top down, so you usually want to start at the highest point on the engine. You can also use a specialty coolant dye paired with an ultraviolet light to trace sources of a leak. And remember, your car’s cooling system is designed for a very specific coolant. Always make sure that you’re using the proper coolant, as recommended by the manufacturer, in your vehicle.

Alright guys, I hope that clears up any questions you have about coolant hoses. If you have a comment about today’s video, please leave that down below. If you want to see more of my videos, head over to and you can check them out there.

Alright guys, thanks so much for watching and I’ll see you next time.

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