I have a Perkins M20 Diesel. I’ve been trying to change the impeller on the cooling water pump. This seems like it should be a relatively easy job but I have pulled on the rubber impeller fins with pliers and vice grips and it doesn’t budge. The only solution I can see is to rip the old impeller apart and peel out the pieces. The pump works ok now and I hate to do something that puts me out of business. Any suggestions?
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RW Pump Impeller
Bill A lot depends on what pump you have, regardless of what engine you have. On our Oberdorfer pump on our Universal M25 engine, you can pull the entire impeller and shaft right out, makes it easy to change the impeller. As Lauraine said, there is usually a little circlip between the end of the shaft facing you and the impeller. It's small and thin, but should be there to hold the impeller on the shaft. Check your pump manual to find out if you can simply remove the shaft and slide it back in again. If not, and if you do, you'd have to remove the entire pump to replace it. Sorry I can't be more specific, but I don't know what pump you have. Stu
Bill A lot depends on what pump you have, regardless of what engine you have. On our Oberdorfer pump on our Universal M25 engine, you can pull the entire impeller and shaft right out, makes it easy to change the impeller. As Lauraine said, there is usually a little circlip between the end of the shaft facing you and the impeller. It's small and thin, but should be there to hold the impeller on the shaft. Check your pump manual to find out if you can simply remove the shaft and slide it back in again. If not, and if you do, you'd have to remove the entire pump to replace it. Sorry I can't be more specific, but I don't know what pump you have. Stu
pump type
The pump is a Jabsco #29350-1001. I have a diagram of the pump parts and it does not show any retaining ring on the outside of the impeller.
The pump is a Jabsco #29350-1001. I have a diagram of the pump parts and it does not show any retaining ring on the outside of the impeller.
Frozen
If you don't have a retaining clip, sounds like the bushing is frozen on the shaft for some reason or the other. If it is, you probably won't be accomplishing anything by tearing the impeller out as the bushing will still be on the shaft and that will be another problem getting it out. I would suggest that you go ahead and get a replacement and see what it looks like before you really get into this. There is a tool specifically designed to pull impellers. If your at a full service marina, the shop probably has one. Luck with it!!
If you don't have a retaining clip, sounds like the bushing is frozen on the shaft for some reason or the other. If it is, you probably won't be accomplishing anything by tearing the impeller out as the bushing will still be on the shaft and that will be another problem getting it out. I would suggest that you go ahead and get a replacement and see what it looks like before you really get into this. There is a tool specifically designed to pull impellers. If your at a full service marina, the shop probably has one. Luck with it!!
For Stu - We have the same pump. Is it
OK to pull impeller and shaft out together? We've been VERY afraid to do this even though the whole thing seems to slide out easily for fear of not being able to line it back up when putting it back. Your thoughts, please.
OK to pull impeller and shaft out together? We've been VERY afraid to do this even though the whole thing seems to slide out easily for fear of not being able to line it back up when putting it back. Your thoughts, please.
Lauraine
Not to walk on Stu, just to give you an answer to your question. The shaft on the Oberdorfer will come out. It does not have gears on the end, just a slot. There is a small o ring/spacer/washer, whatever it is inside of the pump shaft that may drop down slightly, but the end of the shaft itself where the slot is is tapered. I always try to avoid pulling mine out when I change the impeller, but it has come out a few times and there never has been a problem getting it back in. If you do take it out, when re installing it, just twist it back and forth and it will work back in. It's not hard to tell when the slot is engaged.
Not to walk on Stu, just to give you an answer to your question. The shaft on the Oberdorfer will come out. It does not have gears on the end, just a slot. There is a small o ring/spacer/washer, whatever it is inside of the pump shaft that may drop down slightly, but the end of the shaft itself where the slot is is tapered. I always try to avoid pulling mine out when I change the impeller, but it has come out a few times and there never has been a problem getting it back in. If you do take it out, when re installing it, just twist it back and forth and it will work back in. It's not hard to tell when the slot is engaged.
Thanks, J.B.! The manual says to be sure NOT
to pull the shaft out but I think that's for the other type pump. I did accidentally pull the shaft out once (it was SOO easy to do
) but, as you said, it slipped right back in. I thought I was just lucky that time.
to pull the shaft out but I think that's for the other type pump. I did accidentally pull the shaft out once (it was SOO easy to do
) but, as you said, it slipped right back in. I thought I was just lucky that time.
Pump Shaft
Lauraine Glad it worked. Some of the older manuals show the older kind of Oberdorfer shaft, where the inside end of the shaft is indented. The newer shafts have an "extended" little rectangular bump (JB's little slot). Those will go in and out easily. Because of that, it's very easy to have a replacement impeller AND shaft, with the impeller right on the new shaft, ready to go at any time. Just get a new shaft, put a new impeller on it and just swap out both the shaft and new impellers as quick replacements. Actually, it's safer that way if you lose power because of a bad impeller. Thanks, too, JB. Stu
Lauraine Glad it worked. Some of the older manuals show the older kind of Oberdorfer shaft, where the inside end of the shaft is indented. The newer shafts have an "extended" little rectangular bump (JB's little slot). Those will go in and out easily. Because of that, it's very easy to have a replacement impeller AND shaft, with the impeller right on the new shaft, ready to go at any time. Just get a new shaft, put a new impeller on it and just swap out both the shaft and new impellers as quick replacements. Actually, it's safer that way if you lose power because of a bad impeller. Thanks, too, JB. Stu
Yanmar Raw Water Pumps
Fred, I really don't know. I'm intimately familiar with our Universal M25 engine (at least my knuckles are!), but I don't know antyhing about Yanmars. You may want to check with Yanmar sources and just find out what kind of pump they have and whether an Oberdorfer 202-M15 would fit in the engine. Stu
Fred, I really don't know. I'm intimately familiar with our Universal M25 engine (at least my knuckles are!), but I don't know antyhing about Yanmars. You may want to check with Yanmar sources and just find out what kind of pump they have and whether an Oberdorfer 202-M15 would fit in the engine. Stu
impeller extractor
Had the same problem changing the impeller on my Yanmar JH4. Found a device at the local chandlery that has teeth to insert between the blades of the impeller and then turn a screw handle that forces the impeller out something like a corkscrew. Sorry I can't remember the exact name but it works great if you have at least 6 inches of clearance between the impeller plate and some other part of the engine. Greg Beckner S/V Champagne Girl
Had the same problem changing the impeller on my Yanmar JH4. Found a device at the local chandlery that has teeth to insert between the blades of the impeller and then turn a screw handle that forces the impeller out something like a corkscrew. Sorry I can't remember the exact name but it works great if you have at least 6 inches of clearance between the impeller plate and some other part of the engine. Greg Beckner S/V Champagne Girl
Impeller Extraction
I recently used Don Casey's method with success in extracting a tight impeller from my Yanmar 2GM20F water pump: take two screw drivers, put a little tape around the part to the screwdrivers that will pivot on the rim of the opened water pump (you need to be careful not to damage or scar the pump rim surface). Use the two screw drivers to sort of wiggle, or walk, the impeller out by applying alternating pressure, first on one side and then on the other side of the impeller. This worked nicely for me.
I recently used Don Casey's method with success in extracting a tight impeller from my Yanmar 2GM20F water pump: take two screw drivers, put a little tape around the part to the screwdrivers that will pivot on the rim of the opened water pump (you need to be careful not to damage or scar the pump rim surface). Use the two screw drivers to sort of wiggle, or walk, the impeller out by applying alternating pressure, first on one side and then on the other side of the impeller. This worked nicely for me.
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