What Causes Hoses to Become Swollen?

Your radiator serves an essential purpose: it helps to eliminate the heat collected by the engine coolant from the engine. Of course, for it to do this, coolant has to cycle through the radiator from the engine. That job is handled by two radiator hoses – one at the top to handle the heated coolant, and one at the bottom for the cooled coolant.

Radiator hoses are subject to a lot of wear and tear, including heat and pressure. If you’ve noticed that one of the hoses has swollen (usually the upper radiator hose), then it is about to succumb to these threats. First and foremost – a swollen hose is a danger. It could “blow” at any time and should be replaced by a professional immediately.

Why hoses become swollen

There are three primary causes for a hose to become swollen. The first is too much pressure. If you’ve recently replaced your radiator cap, there’s a chance that it is creating too much pressure in the system (this is sometimes seen with generic caps). Second, hoses are subject to wear from the inside out. If the interior of the hose has been worn away, it may look fine to a casual observation, but the rubber has become very thin. Sometimes this creates bubbles or blisters, but if the wear is significant, a large portion of the hose can swell.

Finally, hoses can become swollen when exposed to very high heats. If your engine has overheated (due to a stuck thermostat, low coolant or for some other reason), it’s possible for superheated coolant to swell the hose.

Swollen hoses should be replaced as soon as possible. This applies to radiator hoses, as well as other hoses under the hood. Power steering fluid hoses and brake fluid hoses can also swell up, and this is always a sign of deterioration and impending failure. Work with a trusted mechanic to replace your hoses with OEM-compliant parts.


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Theodore

16 years of experience
1587 reviews
Theodore
16 years of experience
Volkswagen Touareg V6-3.0L Turbo Hybrid - Check Cooling System - Lynnwood, Washington
Theodore was on time and very helpful when answering my questions. He did a great job and I was very happy with his diligence.
Ford Fiesta - Check Cooling System - Bothell, Washington
Punctual, nice and very professional!! He also explained everything very well. I would certainly call him again for the other services required for my car in the future! Thank you Theodore!!!

Jose

17 years of experience
433 reviews
Jose
17 years of experience
Ford Ranger L4-2.3L - Check Cooling System - Portland, Oregon
Jose was right on time and was able to find the source of my leak. He also gave a thorough inspection and found that I had a couple small leaks; not just one, so I appreciated that. He also took the time to explain everything he found and helped me understand what to look for in the future. He got the job completed very efficiently.
Ford F-150 - Check Cooling System - Portland, Oregon
Jose called and was able to come early. He is very knowledgeable and experienced. He needed parts that were not available so he made an appointment that fits both of our schedules to come back.

Derrick

11 years of experience
170 reviews
Derrick
11 years of experience
Audi Q5 V6-3.0L Turbo - Check Cooling System - Fairfield, California
Derrick is a real cool mechanic. He took his time to check every system in my Audi 5.0. He covered all grounds. Even took it out on the freeway just to listen to see if he could hear the problem and see it. Really smart guy! Thanks again D!!

Travis

13 years of experience
579 reviews
Travis
13 years of experience
Saturn Ion L4-2.2L - Check Cooling System - Saint Paul, Minnesota
ON time, courteous and efficient. Did not waste any time at all. Easy personality too. Will likely use him for this kind of maintenance especially for Saturn specific problems! Fair pricing too!

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