Water Pump Part 1 - the disassembly

Water Pump Part 1 - the disassembly


Tom Smith


I have purposely left out diagnosing the pump. I feel if you are at this point you have done that anyway.

Well, the adventure starts. A word of caution (spelled "warning") Do not disassemble the pump until or unless you understand the rest of the steps including inspection and measuring, and reassembly. That is unless you are sure your pump is junk if not rebuilt or just want to see what it is made of.

As you can see you require a few tool for this job. Including a press of some kind, some parallel blocks, and some pieces to use for pushing.

I prefer an arbor press for this job. There is a good feel of what is going on that is not possible with a hydraulic press and it is less likely to cause damage due to the 10, 20, or more tons of force a hydraulic press can exert. There is also less likelihood of parts coming out of an arbor press and even if they do they are much less likely to produce injury. I have an old set of 1,2,3 parallel blocks that I use just for this purpose. For some of the push tools I use some of my sockets. They work fine for the pressure generated by my arbor press but are not safe to use with a hydraulic press.

Just a personal comment, arbor presses are not hugely expensive. They are great for jobs like this and replacing u-joints. Although not frequently used they are a very good addition to a home shop.

Later steps will require some measuring tools and a special tool (a simple lathe project) to install the new seal.

SAFETY FIRST: Presses can be dangerous so a couple of rules. Parts can be "squirted" out at a high rate of speed and with much energy if these rules are not followed.

1) Make sure your press and the parts to be pressed are free of any kind of lubricant, even water.

2) Make sure your setup is square and parallel. Uneven setups can, and probably will, slip easily.

3) Make your setups as short as possible to have the best stability.

4) Wear safety glasses.

You will find several pictures as this series goes on and I will do my best to keep it simple, partly because it really is, and partly because I can make anything complicated if I am not careful.

This picture shows the three main "non-replaceable" parts. The impeller on top, the housing in the center, and the pulley on the bottom. The condition of the impeller would indicate that my cooling system is fairly clean.



The thing to do is remove one piece at a time and it is easier to make the press setup by starting with the largest which is the pulley. Here I have the pulley on blocks so there is enough room for the shaft to clear the pulley bore, and a socket slightly smaller than the shaft bore to push the shaft, and rest of the pump assembly, down through and free of the pulley.


Continuing with the concept of removing the largest piece next I pushed the bearing/shaft assembly from the housing. A note here; when removing the shaft it is OK to push on the shaft unless the bearings are completely gone. In which case a piece to push on the bearing race and fit over the shaft would be needed. During reassembly only push on the race, DO NOT push on the shaft because it will damage the bearings.


The bearing/shaft with seal and impeller after being pushed from the housing.


You got it, remove the next largest piece, the impeller. Again support the work as close as possible still allowing enough room for the shaft to clear the impeller.

A small detail, you may notice that I have the impeller orientated so all four vanes are supported. I did this to make sure the force from the press will be applied as evenly as possible so as to not damage the impeller.


I then pushed off the seal and here are the bearing/shaft combination and the seal. This photo shows some rust which indicates that the seal was leaking. You might consider this, this pump was able to spin by hand with no sign of roughness in the bearings.

For this reason I consider replacing the water pump as a standard part of an engine rebuild.

It might also be of interest that the original pumps had carbon seals which were soft and prone to wear. A quality new seal has a ceramic seal which is much more resistant to wear. The ceramic seal is also more resistant to cracking.


It should only take a portion of the time it takes to read this article to take your pump apart.