23. A Few Hints for Easier Impeller Changing
By Tom Neale, 2/24/2005
A Few Hints for Easier Impeller Changing
By Tom Neale
1. Don’t pry the old impeller out with screwdrivers. These damage the pump lip against which the cover plate is supposed to seal. This can not only result in leaks, but also deformities inside the pump which can wear out the impeller much more quickly than normal. I’ve found that pliers seldom work well and will also sometimes mar the inner pump surface. An impeller pulling tool is worth the cost.
2. Any time you go aground or run your engine in particularly silty water, pull the cover plate and check your impeller blades. Look for cracks in the blades where they join the hub and, of course, for missing blades or parts of blades.
3. It’s best to change your impeller, whether it seems to need it or not, at least once a year, or more, depending upon your use. If the blades fail to the point that they break off, they will be washed against the tubes in the downstream heat exchanger. This can obstruct water flow enough to impair cooling.
4. When the impeller is out, check inside for signs of corrosion, electrolysis, and wear. Have a spare wear plate on hand in case the old one is significantly worn and you need to replace it. You can compare the size of the old one against the size of the new one to see if the old one is badly worn.
5. I prefer to put water pump grease on each side of the cover plate gasket. (The gasket should be a part of the impeller kit.) This helps to hold the gasket in place as I’m fitting the cover plate, and it helps to seal it. When I do the job again, there’s less of a problem cleaning it off than there is with silicone sealants.
6. When putting the new impeller into the pump DO put water pump grease liberally around the walls inside the pump and onto the shaft. Do this to provide lubrication when the pump is picking up water after you’ve resealed it and started the engine. Do it also to help prevent the impeller from binding on the shaft, making it even more difficult to get it out.
7. When putting the new impeller into the pump DON’T put water pump grease on the impeller, and clean all grease thoroughly from your hands. This will help you to grip the impeller, depress the blades, and turn it into the pump. Use a clean rag to help you hold the impeller if it’s gotten greasy.
8. Apply an anti seizing product such as Permatex Anti-Seize 133 K on your cover plate screw threads before you reassemble.
9. Disable your engine from starting (as by unhooking the battery) before you work on it.
10. For a tip on how to depress the impeller blades enough to get the impeller in, without hiring a gorilla with steel fingers, go to www.tomneale.com for more.
Copyright 2004-2005 Tom Neale