Water Pump Seal

Rotorway-Rework

1. The first step is to remove coolant to a level below area to be worked. This is best accomplished by removing the radiator cap and attaching a hose to the bleed valve on the pump body. Have a bucket ready to catch the overflow coolant.
The next step is to disconnect both rubber hoses from the pump. These hoses will have residual coolant so have a bucket standing by to prevent a messy cleanup.

2. To remove the screws that hold the halves together you need a 1/2" ratchet or combination wrench.

3. The aft inboard screw is best removed with the combination wrench.

4. Using a sharp thin blade putty knife split the pump housing. Try not to scar the Aluminum housing and mating surface. Some pumps have gaskets others were assembled using RTV. I found that a dead blow hammer works well in this application.

5. The impeller is now exposed (very sharp edges). Note that the lower housing should be cleaned. Do not damage the mating surface to the impeller. Scotch-Brite works well for this task.

6. This particular pump impeller was exceptionally tight! I find that Oak is the only wood buffer strong enough to hold together when placed against the sharp impeller vanes.

7. Heat was a final resort! I secured the pump shaft with vise grips applied to the upper drive pulley. Whether I hit the impeller with air hammer or dead blow the belts would cushion the blow preventing loosening of the impeller. The combination of heat and a firm blow from a dead blow hammer finally broke the grip of age on the threads. To remove impeller using the oak wood impacting the vane counter-clockwise looking up from the bottom of a mounted water pump

8. Be aware that there is a small spacer below the actual seal. This needs to be carefully pried down the shaft before attempting to drive the seal out. The shaft usually is rusted below the spacer. It helps to remove the rust prior to removing the spacer. Note that the spacer has a "shiny" side where it rides on the seal. Make sure you re-install correctly as removed.

9. Drive out the seal. Using a brass drift punch tap all around the seal to break it loose. This is a tight area be careful not to damage the surrounding area. A steel hammer works best. Try not to score the sides of the Aluminum pump housing.

10. Remove the seal. The seal casing will be crushed by the driving out. This is normal.

11. The shaft gets really rusted! On older ships it may be necessary to replace the shaft. If the pitting is deep enough the seal will not seat with the shaft and leak. Only RWI has the shaft so this would be bad news (expensive). Clean the shaft with steel wool. Do not abrade up and down. Use circular movement around the shaft only. Wipe clean with Acetone.

12. Using the tool, identified later in this instruction, carefully drive the new seal into its seat in upper pump housing. Lubricate both shaft and seal with common dishwasher detergent (Dawn). This tip was offered by US Seal the manufacturer of our seals. Careful not to contaminate the seat area of the seal. A light coat of sealant around the edge of pump cavity is advised.

13. Install the cleaned spacer, correct side up, on to the shaft. Align the impeller with the threads careful not to cross thread and spin on loosely. Verify spacer seated correctly and is flat against lower seal.

14.. Using the Oak and a dead blow against the impeller edge tighten the impeller clockwise looking up. Don't get carried away with hitting this item causing damage to the vanes.

15. Remove all previous seals and sealant from both mating surfaces of the pump housing. Use hand tools only, do not use power tools which may deform the surfaces. If using sealant (RTV Grey) wipe down with Acetone and apply a small amount of sealant to the lower half. You don't want to have the excess extrude into the impeller area of the pump during tightening.

16. Using a tongue depressor or finger spread the sealant to insure coverage of the entire mating surface with minimal excess. More is not better in this application! A little in each hole is okay.

17. I cleaned every screw to remove previously applied sealants. Each screw should be lightly coated with sealant prior to inserting into the pump housing. Again you don't want excessive sealant that could extrude into the pump cavity. Very important! Start all screws before tightening any.

18. Tighten screws equally before final torqueing. I like to accomplish this process using the 1/2" combination wrench. I believe it gives me a better "feel" for tightness. Wipe off extruded sealant from pump seam. Hopefully, there won't be much! Too much may indicate that you over sealed the mating surfaces. Approximately the same amount would be in the pump chamber. Not good!

19. Re-connect the hoses. I advise not to rush the curing of the RTV sealant. Do not fill with coolant nor run the engine the same day you re-assemble the pump.

20. The next day fill the system with the proper 50/50 mix of coolant. It helps to open the petcock on the pump until coolant flows out. Run up the engine IAW the procedure in the builder's instructions and bleed system to purge all air. Verify that the seal is not leaking. If dry, congratulations! If weeping you should be as well, damn!

These are common tools required for this task. The wood buffer is Oak. The heat gun is only if you encounter a very tight impeller. The hook looking device is used for removing coolant hoses. Cheap and available at Harbor Freight. Wrenches required are 1/2" both ratchet and combination. Acetone is used for various cleaning tasks. The steel wool is used to clean the pump shaft. RTV Grey is used to fabricate the seal between pump halves. A gasket is also used on some pumps, your choice.

The only tool I fabricated for this job is a short length of Aluminum tubing. The ID is @ 1.375 with a OD of 1.625. The 1/8" wall thickness affords a good match for the flange on the seal assembly.