How To Install a New Water Pump

Removing a water pump, then installing a new one is a big project, but manageable for a DIY shade-tree mechanic with the right tools.

It's also an excellent chance to inspect other items and replace them as needed, and you should also take advantage of this opportunity and flush the cooling system to get rid of sediment before installing the new water pump to prevent premature failure.

Things such as belts and hoses are far more easily accessible for inspection and replacement when the water pump is out, so now is the time to do so if necessary.

Last but not least is the fan itself which must be inspected for loose rivets, cracks, or bent blades. If you find any damage, do not try to repair it. A fan that's out of balance can break the water pump shaft while in operation, with disastrous consequences.

Clues that may indicate your fan clutch is failing include an engine that starts running hotter than usual and an air conditioning system that no longer performs well.

Inspect the fan clutch and replace it if there's any fluid loss, looseness, or wobble.

My car water temp gauge needle has been reaching for the red line, an indication that something is amiss. An overheating car is not something you want, so I had to do something about mine.

I decided that a prudent idea would be to get rid of the aftermarket water pump I bought when I had the engine rebuilt. I got it either at Advance Auto or AutoZone, I really can't remember, and it's been working okay for the last five years.

Water pumps are not expensive, but I wanted to buy an ACDelco pump not because of originality but because of quality, and my new pump did not let me down.

There are some differences between aftermarket and OEM pumps. Some slight, others more significant with the more obvious one having to do with the overall design which seems to indicate that the ACDelco pump has more coolant capacity than its aftermarket counterpart.

Another small but important difference is how close the belt pulley is to the aftermarket pump versus the factory unit. As long as the pulley does not touch the pump everything is fine, of course, but in my case, that tiny gap always made me uncomfortable and also question the accuracy of the alignment of the pulleys.


Maybe not significant details but even small things such as the coarseness of the casting makes you wonder what the inside passages look like.

From this point on I will try to keep my GM car all GM as the air cleaner sticker reminds us.

Since Chevrolet engines of the era were painted Chevy Orange, water pumps were also sprayed the same color, so I painted my old aftermarket pump orange.

However, upon receiving the ACDelco pump I really liked how the cast-iron finish looked, so I decided to give it a couple of coats of Shellac to help keep corrosion at bay, and forgo painting it. Besides, it really looked great at the very front of the 350 cu. in. block, heads, intake manifold, and valve covers, all painted Chevy Orange.

The new pump included gaskets, but they were too thin in my opinion and I've had excellent results with Fel-Pro gaskets, so I ordered and installed those instead. Just make sure you get two. And even though they are identical, one of the pump/block ports only has two openings (vs. three on the gasket), and you can either leave it like that or trim it to size like I did.


The other issue I wanted to address is how the fan studs are installed, which is something I did wrong on the old water pump as shown in the photo below.

You really don't need to use thread locker on the studs, but if you don't chances are they will come off whenever you need to remove the fan. No big deal and more of an inconvenience when you have to break the nuts loose so you can reinstall the studs on the pump's impeller flange so you can hang and secure the fan onto the assembly.


So I decided that this time I would use Red thread locker so they would stay in place as they don't really need to come out. And I also measured first how far deep I would need to install them so they would provide enough threads for the washers and nuts that secure the fan to it.

When I repainted the fan a few months ago, a couple of the studs came off and I reinstalled them as they were before, which barely allowed three threads to protrude after the fan was installed which wasn't enough in my opinion.

The way I installed them now, I can use a regular Grade-8 nut along with a flat washer and they provide enough threads so I can properly tighten them. I also add a drop of blue thread locker for peace of mind.



The photo above shows one of the studs with the pulley in place, and you can see that the stud sticks out far enough for the fan flange (which covers the stud's shoulder), with plenty of threads sticking out for a washer and nut as shown in the photo below.


To prep the block surface so the new gaskets would seal properly, I carefully cleaned the area with a sharp blade. Again, the Fel-Pro gaskets I used are supposed to be installed dry, so there's no need for RTV or anything like that.

As a matter of fact, I was pleased to see that the shop that installed the old pump also installed thinner gaskets without any sealers, which makes cleaning a lot easier.

And if you are wondering, the old pump never leaked coolant from these ports.



Some, if not all of the four block threaded holes (to which the water pump bolts to), are not blind holes. In other words, they go all the way through into the water jacket behind the pump. This means that the bolts could potentially leak through wicking action, unless they are sealed properly.

For this, I used Permatex Thread Sealant (sponsored), a paste that you brush onto the bolt threads before you install them. Thread locker DOES NOT seal the threads, so you must use thread sealant to prevent leaks.

Since you are trying to bolt a somewhat heavy/awkward pump to the block while at the same time ensuring the gaskets are seated and positioned properly as you start securing the bolts, while these components are in a vertical position, the task is frustrating, to say the least.

Therefore, I use small dabs of spray glue to hold them in place so I don't have to worry about them getting damaged or falling under the car. This makes installation far easier, especially when you're working all by yourself.

Having said all that, if a picture is worth a thousand words, then a video is worth several hundred thousand.

The three videos below cover the removal of the pump, preparation of the pump and related items, as well as installation, followed by engine start-up and more.




Please keep in mind that nothing happens until you start turning wrenches and that all the text, photos, and videos in the world can only give you a basic understanding of what's involved.

As you probably know, I work alone, and even though I have a tripod, I am severely limited as to how much (or how well) I can film, as I usually try to do so while performing or completing the task I am filming. And I do all without fancy cameras or setups. Just my iPhone and a cheap tripod.

Anyway, I hope this article gives you a basic idea as to what's involved for removing and replacing the water pump on a C3 Corvette.

Thank you for following my '76 Vette Blog!