I'm about to change the impeller on my Universal M25 for the first time. It has an Oberdorfer water pump. Any tips on how to avoid removing the impeller shaft with the impeller- the manual says to take care to avoid removing the shaft because it may be difficult to replace correctly.
- Status
M25 Oberdorfer Shaft
Dave What year is the engine? Mine's a 1986 and the shaft CAN come out and be easily replaced. Long story, let me know first. Stu
Dave What year is the engine? Mine's a 1986 and the shaft CAN come out and be easily replaced. Long story, let me know first. Stu
Stu- Engine is 1985
Stu- the engine is the original 1985 M25. BTW, I see that you are berthed in SF. Where do you haul-out for botom painting and would you recommend the yard- I'm due this winter.
Stu- the engine is the original 1985 M25. BTW, I see that you are berthed in SF. Where do you haul-out for botom painting and would you recommend the yard- I'm due this winter.
M25 Impeller
My 1987 M25 was sort of easy. Remove the cover, four screws. Inside you will find the impeller is held in place with a "C" clip. You need a special clip remover that makes this really easy. The clip has two holes for you to incert the "spreader" tool. Once the clip is removed, put a small screw driver against the center of the shaft and pull the impeller off. On the new impeller I used to put white greese. Usually though for off season I left it out till spring. Hope this helps. Paul
My 1987 M25 was sort of easy. Remove the cover, four screws. Inside you will find the impeller is held in place with a "C" clip. You need a special clip remover that makes this really easy. The clip has two holes for you to incert the "spreader" tool. Once the clip is removed, put a small screw driver against the center of the shaft and pull the impeller off. On the new impeller I used to put white greese. Usually though for off season I left it out till spring. Hope this helps. Paul
Oberdorfer Shaft Info
Dave I wrote this up on our C34 website. See the link. We're at Grand Marina in Alameda. I use Mariner Boat yard which is right there. They usually have a December special that includes haul, bottom job and a free boat wax. Nice folks, good work, although a long haul for you unless you come in the back way through San Leandro Bay just north of the airport. It's doable at high water. I can help you with directions if you want, you get to open four bridges, too!!! Let me know. Any more details, try my email, sec@c34.org. Stu
Dave I wrote this up on our C34 website. See the link. We're at Grand Marina in Alameda. I use Mariner Boat yard which is right there. They usually have a December special that includes haul, bottom job and a free boat wax. Nice folks, good work, although a long haul for you unless you come in the back way through San Leandro Bay just north of the airport. It's doable at high water. I can help you with directions if you want, you get to open four bridges, too!!! Let me know. Any more details, try my email, sec@c34.org. Stu
remember to check the direction
Dave, In case you didn't know this already, after you remove the water pump cover, remember to note which way the vains on the impeller are bent toward. When you install the new impeller you will have to re-install it with the veins facing the same way. If you don't it will not pump water and you will have to open the pump up and do the job all over again.
Dave, In case you didn't know this already, after you remove the water pump cover, remember to note which way the vains on the impeller are bent toward. When you install the new impeller you will have to re-install it with the veins facing the same way. If you don't it will not pump water and you will have to open the pump up and do the job all over again.
Thanks to all
Thanks to everyone for your advice. I also found some helpful information in the Nigel Calder book on boat maintenance in the water pump chapter.
Thanks to everyone for your advice. I also found some helpful information in the Nigel Calder book on boat maintenance in the water pump chapter.
Not quite right
Gaspar, If you were to replace the impeller with the blades facing the "wrong" way, within a half revolution the blades would be facing the correct way and the pump would be pumping water. The rubber will bend either way, and friction will quickly get the blades lined up. I know because I've done it often!!!
Dave, Removing the shaft will do no harm, as long as you don't run the engine with the shaft removed. I think it's a LOT easier to take out the shaft with the impeller attached, change the impeller, and then put the two of them back in as a unit. You might have to slightly turn the shaft to get it to line up with the indent inside the engine, but it's not hard at all. A few small dabs of vaseline on the impeller will help with the install, but not too much, as it may clog the water passages somewhere downstream.
Gaspar, If you were to replace the impeller with the blades facing the "wrong" way, within a half revolution the blades would be facing the correct way and the pump would be pumping water. The rubber will bend either way, and friction will quickly get the blades lined up. I know because I've done it often!!!
Dave, Removing the shaft will do no harm, as long as you don't run the engine with the shaft removed. I think it's a LOT easier to take out the shaft with the impeller attached, change the impeller, and then put the two of them back in as a unit. You might have to slightly turn the shaft to get it to line up with the indent inside the engine, but it's not hard at all. A few small dabs of vaseline on the impeller will help with the install, but not too much, as it may clog the water passages somewhere downstream.I installed it wrong
Tom, I guess you had better luck than me. I installed one with the blade facing the wrong way and it didn't pump. I started the engine, looked over the stern and not a drop just as it was explained in the manual. I opened the pump up, fliped the blades and this time plenty of water. Go figure.
Tom, I guess you had better luck than me. I installed one with the blade facing the wrong way and it didn't pump. I started the engine, looked over the stern and not a drop just as it was explained in the manual. I opened the pump up, fliped the blades and this time plenty of water. Go figure.
- Status