- Status
6 or 8 tiny bolts on the back side
Depending on how your impeller is installed, usually the back cover will come off after removing the small bolts. When I say back, I mean the opposite side of the belt. It is usually mounted with the belt side out. You have to remove the 2 bolts holding the housing to the engine, then remove the housing, flip it over, and you should see the tiny bolts. Remember, there is also a paper gasket under there. If you are careful, you can reuse it.
Depending on how your impeller is installed, usually the back cover will come off after removing the small bolts. When I say back, I mean the opposite side of the belt. It is usually mounted with the belt side out. You have to remove the 2 bolts holding the housing to the engine, then remove the housing, flip it over, and you should see the tiny bolts. Remember, there is also a paper gasket under there. If you are careful, you can reuse it.
What I usually do
I usually disconnect the two hoses (in/out) and entirely remove the pump to work in it. I'll take it to the shelf and work on it, much more easily, there. Remove the back plate. It's much easier to replace the gasket since it tears easily. Besure to remove the gasket entirely and smooth out the contact surfaces. Change the impeller and reassemble with a new gasket. Replace the screws in a "star" fashion so as the apply even pressure to the plate. Do not overtighten. Reconnect the pump. Set the belt tension and you are on your way. When used to doing it, it should only take you 15-30 minutes to do the job.
I usually disconnect the two hoses (in/out) and entirely remove the pump to work in it. I'll take it to the shelf and work on it, much more easily, there. Remove the back plate. It's much easier to replace the gasket since it tears easily. Besure to remove the gasket entirely and smooth out the contact surfaces. Change the impeller and reassemble with a new gasket. Replace the screws in a "star" fashion so as the apply even pressure to the plate. Do not overtighten. Reconnect the pump. Set the belt tension and you are on your way. When used to doing it, it should only take you 15-30 minutes to do the job.
a few more suggestions to add to a good list.
1. if you remove the hoses to work on the bench. Mark one of the hoses with tape to make sure you re-assemble in the correct sequence. 2. When you go to remove the screws on the back cover- "break" with pair of locked-down vise grips as a screwdriver will strip the head off "old" brass screws. Replace the screws with new ones- they are inexpensive insurance against rounding out the screw head. 3. If your cover has a grove in it from the impeller, replace cover or polish reverse side and install that side. 4. To install new impeller, wrap with thread in a clockwise manner on outside edge, pull thread to bend impeller blades to make smaller and then remove thread when installed. 5. new gasket when putting back together. If no gasket, use #2 permatex or similiar as you want NO air leaks. Air leaks will not result in water leaks but will allow prime to break and your engine WILL overheat and you will not know why.
1. if you remove the hoses to work on the bench. Mark one of the hoses with tape to make sure you re-assemble in the correct sequence. 2. When you go to remove the screws on the back cover- "break" with pair of locked-down vise grips as a screwdriver will strip the head off "old" brass screws. Replace the screws with new ones- they are inexpensive insurance against rounding out the screw head. 3. If your cover has a grove in it from the impeller, replace cover or polish reverse side and install that side. 4. To install new impeller, wrap with thread in a clockwise manner on outside edge, pull thread to bend impeller blades to make smaller and then remove thread when installed. 5. new gasket when putting back together. If no gasket, use #2 permatex or similiar as you want NO air leaks. Air leaks will not result in water leaks but will allow prime to break and your engine WILL overheat and you will not know why.
Impellar changing
The engine on my 1990 Hunter 27 is a yanmar 1gm10. The housing for the impellar is located below the pulley and to the right. It has 2 screws that are easily accessible. THe 3rd screw is obscured by the pulley itself. How do I access the third screw without removing the pulley?
The engine on my 1990 Hunter 27 is a yanmar 1gm10. The housing for the impellar is located below the pulley and to the right. It has 2 screws that are easily accessible. THe 3rd screw is obscured by the pulley itself. How do I access the third screw without removing the pulley?
Some More Suggestions
To add on to what others have said, here are some more impeller changing suggestions: 1. Spread waterpump grease liberally inside the waterpump and on the impeller shaft. This will help lubricate the impeller blades during startup while the pump is sucking water in. Aslo, put some grease on both sides of the cover gasket as this will help to hold it in place a bit. 2. Use anit-sieze on the little screws that hold the plate on. Everybody has commented on how difficult it is to remove the screws and that's true - the anti-sieze will help the next time you do work on it. 3. When installing the new impeller make sure it has no grease on the blades and there is no grease on your fingers or the waterpump housing to avoid things slipping. Since there is grease on the inside of the waterpump housing there is no need to put additional blades on the impeller blades.
To add on to what others have said, here are some more impeller changing suggestions: 1. Spread waterpump grease liberally inside the waterpump and on the impeller shaft. This will help lubricate the impeller blades during startup while the pump is sucking water in. Aslo, put some grease on both sides of the cover gasket as this will help to hold it in place a bit. 2. Use anit-sieze on the little screws that hold the plate on. Everybody has commented on how difficult it is to remove the screws and that's true - the anti-sieze will help the next time you do work on it. 3. When installing the new impeller make sure it has no grease on the blades and there is no grease on your fingers or the waterpump housing to avoid things slipping. Since there is grease on the inside of the waterpump housing there is no need to put additional blades on the impeller blades.
One more suggestion
Those little bronze screws that are being mentioned. The Phillips head WILL strip very easily (believe me, I know). But Yanmar has now replaced them with little bronze bolts that you can use a small socket on. They won't strip, but they are stll SOFT and require gentle hands, as well. DO NOT overtighten!
Those little bronze screws that are being mentioned. The Phillips head WILL strip very easily (believe me, I know). But Yanmar has now replaced them with little bronze bolts that you can use a small socket on. They won't strip, but they are stll SOFT and require gentle hands, as well. DO NOT overtighten!
Use a rubber band
Before you put in the new impeller, you can use a rubber band and wrap it tightly around the impeller, then you can easily slip the impeller into the hole. Before it in entirely in the hole, remove the rubber band, then push it in rest of the way.
Before you put in the new impeller, you can use a rubber band and wrap it tightly around the impeller, then you can easily slip the impeller into the hole. Before it in entirely in the hole, remove the rubber band, then push it in rest of the way.
Someone finally got their act together
at Yanmar. On the new 54 hp they turned the impeller so that the cover is facing away from the engine, making it MUCH easier to work on.
at Yanmar. On the new 54 hp they turned the impeller so that the cover is facing away from the engine, making it MUCH easier to work on.
That's really nice
Brian: Do you know if they are doing that with all of their engines, or just the 54 hp? To bad there isn't an easy way to convert from the old to the new style without having to change out the whole engine. On second thought, there probably is a way to convert it, but will have to fabricate a sturdy mount that will reverse the housing and pulley, essentially mounting it upside down. Then the pre-bent hoses won't work. That is just way too much work.
Brian: Do you know if they are doing that with all of their engines, or just the 54 hp? To bad there isn't an easy way to convert from the old to the new style without having to change out the whole engine. On second thought, there probably is a way to convert it, but will have to fabricate a sturdy mount that will reverse the housing and pulley, essentially mounting it upside down. Then the pre-bent hoses won't work. That is just way too much work.
Not sure on others
J.C., I'm not sure about any other size motors, but they had just made the switch late last year. Yanmar reconfigured the old 56 and made it a 54. My '05 44ac has the new motor, but as I understand, the '04s did not. Brian
J.C., I'm not sure about any other size motors, but they had just made the switch late last year. Yanmar reconfigured the old 56 and made it a 54. My '05 44ac has the new motor, but as I understand, the '04s did not. Brian
- Status