Water Pump Part 3 - assembly

Tom Smith

Before assembly I cleaned my housing and painted the pulley. I painted the housing after the bearing /shaft was installed. I was careful to not get any paint in the bores or on the shaft and applied only a thin coat to the pulley belt area so the belt can easily wear away the paint where it makes contact.

One more thing before starting. I contacted John Crane, Inc, which is a company that produces seals and talked at length to one of their technical reps, who recommend one of their seals, S106MAST, which is a ceramic seal with stainless components. He also recommended Harold Bishop's HdrK CO, Inc. in Albany, Indiana. (765) 789-4406. I called Harold and gave him the measurements I took (see part 2) and he recommended the following shaft. W2446; shaft length 4.469; pulley end length 1.081; vane end length 1.859; shaft diameter 0.6267.

Harold had both the seal and bearing/shaft in stock and I had them in a couple days. I add that Harold knows his stuff and was eager to share his knowledge. He was the source for the dimensions of the push tool for the seal shown later in this article.

The reason I did not include those dimensions is that if you do not order the same seal the dimensions may be different.

Then it was time to reassemble the water pump. This is really pretty easy but care must be given to get the spacing correct. A press, set of feeler gages, caliper, and the push tool to get the correct tension on the seal spring will be needed.

I will cover the process in order of the procedure. The first step being the installation of the bearing/shaft in the pump housing.

There are two things to be careful to do here. The first being to make sure to have the shaft orientated properly so the correct end lengths are in the correct position. The second is to have something to push the bearing in by only making contact on the outer bearing race. Pushing on the shaft can damage the bearings. Here I used a deep socket that is large enough to sit on the outer race and small enough to fit in the housing bore with out getting stuck. It also must be long enough inside to not interfere with the end of the shaft.

I then placed the housing, bearing/shaft, and socket in the press. Care must be taken to have these parts in alignment and square to the press. It is also important to have clearance below the housing for the shaft to clear.

These photos show the location of the bearing in my housing. This does not have to be within any particular dimension but you should center the bearing to the bore surface that supports it.

These photos show how the seal fits in the housing. I used some locktite on the flange when assembling to help the flange press in and to help it seal in the housing. I did not use any sealer on the shaft but the same could be done there. Do not get any on the seals themselves. I also mention that it is important not to drop the seal, the ceramic parts are tough but can be cracked by a blow.

This is the seal driver my brother made for me. It is brass only because it happened to be what was handy, it could have just as well been made of nylon or UHMW or steel. The second photo shows how the seal fits in the driver. It is important to use a press to install the seal. Using a hammer would likely cause damage to the ceramic seals.

The following sequence of photos show the actual installation of the seal. Again, make sure all parts are aligned and vertical in the press. For this process the shaft should be on the press platen. Notice that as the seal gets very near to being seated that the tool makes contact with the flange and from that point installs both the shaft and bore portions of the seal as a unit in a compressed state. This is the reason for the tool. To place the proper tension on the spring so the seals do not leak and so they are not so tight that they wear quickly.

This next step is very important to the function of your pump. The spacing between the vanes of the pump and surface in the mating housing needs to be about .030in. If much more the pump can have a tendency to cavitate. If it is too close the pump may rub or just work harder. I measured the vane hight on the impellers of both my old pump and the Asian replacement I purchased. With both the vane height was not consistent between the four vanes on each impeller. They varied by as much as .007in.

The next part of this step is to measure the thickness of your pump gasket. Mine is .032in using my caliper. Remember that the caliper accuracy range would indicate that that may be from .030in to .034in. A side note here, if for any reason you remove your water pump it is important to replace the gasket with a proper gasket to maintain the pump spacing.

With that in mind I pressed the impeller on the shaft. I did not press mine fully to the shaft end, but left a small amount of space.

I then placed the pump in the mating housing and using a feeler gage went around and checked the amount of space between the castings. Because of the variance of the vane heights there was a small difference in readings. Because I did not want the impeller to rub I used the largest readings. By using this method and some simple math I determined the remaining distance to push the impeller. I made a spacer of the required thickness and placed it under the impeller in the press and pushed it to its final position. I then rechecked and was satisfied when the impeller just cleared the inside of the mating housing. The gasket thickness then giving me the proper spacing.

This photo shows the final position of my impeller.

It is fairly straight forward to install the pulley. But remember to push on the opposite shaft end. If the other end is inside the impeller use a small socket or other piece on the shaft inside the impeller to insure the impeller position is not changed. To be certain of the pulley position for your vehicle, install the pump with the gasket and lightly tighten the nuts. Use a straight edge across your lower belt pulley and to the edge of the pump pulley. That will show if the position is correct for your vehicle. Something you do not get with a purchased replacement.

Well, I hope this has taken the mystery out of rebuilding your own water pump.

Pardon me for this vanity. This is my press. It was originally one with a handle that had to be fully rotated when operating it. I made the ss handle, ss fulcrum weldment, tool steel ratchet parts, aluminum release ramp, platen, Delrin internal bearings, and added the handle. The ratchet mechanism now allows the handle to work similar to that on a bumper jack.