Replace Upper & Lower C3 Corvette Radiator Hoses

Replacing radiator hoses is part of the long-term maintenance program for an internal-combustion, water-cooled vehicle.

In the case of the C3 Corvette, removing and installing a lower radiator hose (if the factory shroud is present), is a challenging, frustrating, and even infuriating task. There's no other way to describe it.

My original plan was to film the process in detail, but as you probably know, I work alone. So when I found myself under my Corvette trying to loosen the lower hose clamp with my right hand while holding the hose with my left, I was going to use my third hand to hold the camera, but then I remembered I only have two!

I hope the video at the end of this article will give you a good understanding of the struggle of removing and installing a new lower radiator hose, as well as tips and tricks I utilized to get mine properly installed and leak-free.

The upper radiator hose is so easy to remove and replace there's not much to talk about, except for routing it properly so it does not rub against the radiator shroud, the air intake, or the alternator bracket.

For this project, I bought Dayco hoses from Advance Auto Parts, which are fine, but you can buy ACDelco or Gates hoses from Amazon (links below). But regardless of where you purchase them, make sure they are molded and an exact fit for your model year.

Also, older lower hoses had a metal spring inside to prevent them from collapsing under extreme vacuum conditions, but this is 40-plus years later (better materials, manufacturing methods, etc.), and while any radiator hose can collapse due to vacuum or suction, if that happens, you may want to find out the exact cause instead of attributing it to the lack of a spring.

Personally, I don't think an internal spring is necessary. However, if you want to install one, several auto part vendors offer them. But get the best anti-collapse spring you can find, so it won't start rusting the moment it is flooded by engine coolant.

The photo above is from the Haynes 1968-1982 Corvette repair manual. Having a copy handy is a good idea. This is the only publication that showed a good picture of the upper radiator hose and its routing.

If the upper radiator hose contacts the alternator bracket, you can adjust it slightly so it does not or, alternatively, add a rubber cushion to insulate it.

Again, the upper radiator hose is super easy to replace, although the task may be complicated a bit if your car still has the smog pump which you must move out of the way to get the old lower radiator hose out and a new one installed.


If your Corvette's radiator, core support, and shroud are out, this is the perfect time to install a new lower radiator hose.

However, IT IS possible to remove the old hose and install a new one with all the aforementioned parts in place. It may not be easy, but it is doable.

Having a QuickJack portable lift available made this job bearable. If you have a full-size car lift or access to one, you are golden!

The first thing I did was to remove the lower radiator hose shield shown above, held in place by an 11/16" nut. That shield protects the hose from the a/c belt.

Old hoses get "welded" to the water pump and the lower radiator coolant outlet neck. The best and quickest solution is to use a utility knife and slice the hose longways right where it contacts the water pump and radiator. Then peel it off those areas.

I had to slice mine a couple of times so I could separate it from the components. At this point, old hoses become sacrificial, and by slicing them you prevent damaging other parts as they are removed.

I also cleaned, lubed, and reused the original hose clamps. And they can be split open so they can be installed after the hose is in place, which is very convenient.

If you have to purchase new hose clamps, buy the best ones you can find. I've used cheap clamps before and they usually immediately fail when you over-tighten them. Good clamps will not fail unless you over-tighten them with a socket and a breaker bar.

I bought Ideal/Tridon SmartSeal hose clamps at the local auto parts store, and they are the best I've ever used.


To make installation as painless as possible, I lubed the lower radiator hose inside ends to get them to slide over the water pump and lower radiator outlet easily.

You can use something like dish detergent or a water-soluble lubricant. Yes, the kind intended for personal use. However, do not use anything petroleum-based as it can damage rubber hoses.

I also lubed the exterior of the hose to slide it into position, something I found out, is easily achieved from under the car as explain in the video.

As a side note, a water-soluble lubricant will evaporate quickly and leave no harmful residue behind. A dish detergent may contaminate the coolant, so keep that in mind.

There are several water-based lubricants intended for automotive use, so you have options.

I was able to complete the job only to discover that my copper radiator had sprung a leak, which was the perfect excuse to purchase a 3-row aluminum radiator by Champion.

I am working on a video series about the installation of the new aluminum radiator so please subscribe to my YouTube channel and turn on post notifications to receive a message when I upload new videos.

In the meantime, I hope the video below will give you a better understanding of replacing both radiator hoses, especially the lower hose.

There are other things you can do to make this job easier. A lot easier in fact. However, they will require more time and additional parts to be removed.

If your Corvette doesn't have air conditioning, that is a plus since loosening the radiator core support will allow you to tilt it forward far enough so you can remove the shroud. In one piece!

On the other hand, if your car does have A/C, then the only way to do this without damaging the condenser is to remove the headlamp actuators. At this point, you might as well just huff and puff and get the job done with the shroud in place. I did it.

Removing the shroud is yet another frustrating job that only gets more complicated when you fail to get enough parts out of the way, but once the shroud is out of the way, installing the lower radiator hose is fairly simple and easy.

The picture below is of the new aluminum radiator during installation, but it also shows how the inlet water neck is easily accessible with the shroud out of the car.

To remove the shroud you will need to remove four of the six bolts that secure the core support in place to the inner fenders and loosen the other two that secure it to the chassis, as this will allow you to rotate it out of the way. You will also need to remove two nuts at the bottom, next to the lower radiator stays plus the upper stays and brackets. 

You will also need to disconnect the upper hose at the inlet radiator neck, which is very easy to do.

Again, this can become quite an involved job if you want to do it right, and I don't want to discourage you from giving it a shot, but if you have the money, an experienced Corvette mechanic can save you a lot of aggravation and frustration.

It won't be cheap, but it will be done right and you get to keep your sanity.

So yes. This is not an easy DIY project by any means, and I had to walk away from it a few times. I am fortunate to have a large garage and a QuickJack lift at home, which makes the job so much easier.

I hope this article and video will give you a better understanding of what's involved to remove an old lower radiator hose and install a new one.

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