I recently read an article in "Good Old Boat" that recommended taking the impeller out of your raw water pump over the winter so that it won't take a "set" and perhaps work less efficiently, or at all, when you stoke up the engine in spring. I used to do just that until a friend, with the same Yanmar 2GM20F, told me he leaves his impeller in all winter. He uses the same impeller for two seasons, and then replaces it in the spring of the third year. He tells me that when he takes the old impeller out it is still in very good condition, has no "set" whatever, and he keeps it as an emergency spare. I recently one of his used impellers and it looked great to me. What do you do?
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Leave it in
When you Winterize the engine, antifreeze goes into all the hoses and raw water system. It's a lubricant in itself. Unless it's time to change the impeller,why take things apart. Dave
When you Winterize the engine, antifreeze goes into all the hoses and raw water system. It's a lubricant in itself. Unless it's time to change the impeller,why take things apart. Dave
impeller set
It will take a set if left in the same position for months, regardless of the presence of antifreeze. Whether or not that is a problem is arguably impossible to tell until you try it in the spring so why take the chance? It's really simple to remove it and replace in the spring - doing so will also allow you to inspect it to see if any vanes are missing or cracked. My thought is that it's pretty cheap insurance to replace often since a cursory inspection won't tell you how much life it has remaining
It will take a set if left in the same position for months, regardless of the presence of antifreeze. Whether or not that is a problem is arguably impossible to tell until you try it in the spring so why take the chance? It's really simple to remove it and replace in the spring - doing so will also allow you to inspect it to see if any vanes are missing or cracked. My thought is that it's pretty cheap insurance to replace often since a cursory inspection won't tell you how much life it has remaining
We sail all year long
so it stays in until we replace it, usually every year or two. Whether the impeller is in a pump and not being used, or is used once every week or two, it's still being compressed. I would think the cold would have the potential for doing more damage that the position of the vanes.
so it stays in until we replace it, usually every year or two. Whether the impeller is in a pump and not being used, or is used once every week or two, it's still being compressed. I would think the cold would have the potential for doing more damage that the position of the vanes.
Inspect Impellers center
I replace my impeller every 2 years, like this spring. but I leave it in during the winter months. last year it didn't get really cold here until February & March December and January were mild compaired to years past. Make sure you check the Keyway sleeve or ring in the center of the impeller, the only one to ever fail on me was made of a plastic type material, where the keyway just chewed up the center and if you looled at the impeller you would find nothing wrong with the blades.Now I make sure the replacements have the metal sleeve.With the cold winters we get, I've had no problems leaving it in during the winter.
I replace my impeller every 2 years, like this spring. but I leave it in during the winter months. last year it didn't get really cold here until February & March December and January were mild compaired to years past. Make sure you check the Keyway sleeve or ring in the center of the impeller, the only one to ever fail on me was made of a plastic type material, where the keyway just chewed up the center and if you looled at the impeller you would find nothing wrong with the blades.Now I make sure the replacements have the metal sleeve.With the cold winters we get, I've had no problems leaving it in during the winter.
In the five years since we purchased our...
boat I have yet to pull the impeller. No idea how long it was in before that. I know when I replace it some day with the new spare, it will not have a "set". A visible inspection shows that it is in good condition. The PO kept the original one, which I also keep as a spare and it does not have a "set". Of course the 15 year old engine just has 1,100 hours total. I estimate the current impeller has about 500 hours. Terry
boat I have yet to pull the impeller. No idea how long it was in before that. I know when I replace it some day with the new spare, it will not have a "set". A visible inspection shows that it is in good condition. The PO kept the original one, which I also keep as a spare and it does not have a "set". Of course the 15 year old engine just has 1,100 hours total. I estimate the current impeller has about 500 hours. Terry
Jerry, one thing;
Be sure to remove the pieces of your old impeller. They are probably blocking the cooling tubes in your heat exchanger. It's easy to do. Just undo the four bolts holding the cap on.
Be sure to remove the pieces of your old impeller. They are probably blocking the cooling tubes in your heat exchanger. It's easy to do. Just undo the four bolts holding the cap on.
Fred - got them out Thanks for the heads up!
Got them out when it was changed. Won't ever go that long again.
Got them out when it was changed. Won't ever go that long again.
Jerry's impeller
Jerry, what have you been doing with that impeller? Does your boat have a strainer on the hull and hose? Our 29.5 had a strainer on the outside of the hull and in 10 years we never had to replace the impeller (Arkansas fresh water lakes). Our 340 does not have the hull stainer but does have a filter between the through hull and the impeller. Did you ever run the motor with the through hull closed? Or maybe impellers just ain't what they used to be?
Jerry, what have you been doing with that impeller? Does your boat have a strainer on the hull and hose? Our 29.5 had a strainer on the outside of the hull and in 10 years we never had to replace the impeller (Arkansas fresh water lakes). Our 340 does not have the hull stainer but does have a filter between the through hull and the impeller. Did you ever run the motor with the through hull closed? Or maybe impellers just ain't what they used to be?
I leave my impeller in
over the winter. Since I try to visit the boat once or twice a month, each time I'm there I hand rotate the water pump pulley just a quarter turn or so in order to change the location of the impeller blades under the cam. I sometimes open the pump cover in spring and take a look at the condition of the impeller and then either replace it (if it looks faulty) or just put on a new gasket and close it back up. I typically replace the impeller after the second season or after about 100-150 hrs of usage, unless I had reason to believe it needs replacement sooner (i.e., running aground and sucking up sand into the raw water system in order to motor off). Grit in the pump will kill an impeller very quickly. It may also kill your pump ($$$$), too.
over the winter. Since I try to visit the boat once or twice a month, each time I'm there I hand rotate the water pump pulley just a quarter turn or so in order to change the location of the impeller blades under the cam. I sometimes open the pump cover in spring and take a look at the condition of the impeller and then either replace it (if it looks faulty) or just put on a new gasket and close it back up. I typically replace the impeller after the second season or after about 100-150 hrs of usage, unless I had reason to believe it needs replacement sooner (i.e., running aground and sucking up sand into the raw water system in order to motor off). Grit in the pump will kill an impeller very quickly. It may also kill your pump ($$$$), too.
Have strainer
Have strainer and correct setup. Never ran without the thru hull open. Condition of impeller was pretty rough. That was the first time it was changed, but I am now planning on changing each year. Will have another one this spring with 82.8 hours and will see how it compares.
Have strainer and correct setup. Never ran without the thru hull open. Condition of impeller was pretty rough. That was the first time it was changed, but I am now planning on changing each year. Will have another one this spring with 82.8 hours and will see how it compares.
Warren and list...
last season was the second one on a new impeller. Last winter I pulled it, this year I didn't because it will get changed next spring. Don't forget to loosen your "fan" belts too. They'll take a set if left tensioned around the pulleys over an extended period of time. I took mine off and examined them and was shocked to find a "slice" (for want of a better word)from the v end up to the belts on the alternator belt that was not readily evident when tensioned. Cheap insurance! Oh, and I carry two sets of spares of all these critical items.
last season was the second one on a new impeller. Last winter I pulled it, this year I didn't because it will get changed next spring. Don't forget to loosen your "fan" belts too. They'll take a set if left tensioned around the pulleys over an extended period of time. I took mine off and examined them and was shocked to find a "slice" (for want of a better word)from the v end up to the belts on the alternator belt that was not readily evident when tensioned. Cheap insurance! Oh, and I carry two sets of spares of all these critical items.
Leave mine in to keep the engine cool
We had a nice sail Saturday. It got up to about 74 degrees and a nice breeze. It would be a real pain to take out the impeller after sailing and then put it back in before sailing. Is it the cold water that is supposed to make it set?? It is such a pain that whenever I take out my impeller I replace it with a new one. I had to fish out a broken blade a year or so ago. Fortunately I could just grab it with some hemostats.
We had a nice sail Saturday. It got up to about 74 degrees and a nice breeze. It would be a real pain to take out the impeller after sailing and then put it back in before sailing. Is it the cold water that is supposed to make it set?? It is such a pain that whenever I take out my impeller I replace it with a new one. I had to fish out a broken blade a year or so ago. Fortunately I could just grab it with some hemostats.
not me
Because I probably would forget to put the impellor back in the spring, and then I'd have a bigger problem.
Because I probably would forget to put the impellor back in the spring, and then I'd have a bigger problem.
A warning to those of you who might go to the local chandlery for a new impeller. We replaced the impeller on a Yanmar 2GM20F YEU in April 2006. We put very few hours on the engine during the six months of this past summer. The engine ran normal right up thru haulout on the day after Thanksgiving. But when we disconnected the sea water intake hose and tried to pump a gallon of antifreeze thru the salt water system, Nada, zero!! Nothing pumped. Opened up the pump casing and discovered that the engine had eaten two whole impeller blades!!! All we can figure out is that the impeller installed in April must have been on the shelves of the local marine dealer for a long time and was probably brittle. The good news was that it must have broken just as we shut down the engine for haul out, because there was no overheating while it was running. How seldom does one get a break like that? The lesson here is that impellers apparently do have a shelf life. Torresen Marine's repair guy says that a good way to test for viability, is to bend over one or more impeller blades, and if they are inflexible, crack, or have trouble returning to normal configuration, then the impeller is old and should not be used. He said that Torressen pays attention to shelf life of their stockage. By the way: the 2GM20F engine model number is insufficient data for ordering some parts on this Yanmar (and perhaps size engines). Turns out that when the Yanmar serial starts with an "E", then the engine is a European Yanmar and a number of parts can be different from the Japanese models for instance impeller, pump "O" ring (vs paper gasket), and two belts. The European Yanmar is described by the model number 2GM20F YEU, even though Yanmar doesn't put that "YEU" on their engine label. It is not intuitively obvious in Torresen's web site that you have to be aware of this fact. Caveat emptor!!!!!!!!
Impellers and Belts...
One of the many things that will shorten, perhaps drastically, the life of an otherwise "good" impeller is sucking up grit into the your water pump. If you have any reason to believe that you've done so (i.e., gone aground, etc), best to check and/or replace your impeller. Sand or grit works like sandpaper moving at high speed if it gets into your water pump. Not only could it destroy your impeller, it could also damage or ruin your water pump. To the poster below who described a cut in his water pump belt, I had the same thing happen with an almost new belt I bought from Torreson. The belt was properly tensioned and the pulleys were in good condition. One day while checking the engine prior to a sail, I just happened to notice that my newish OEM belt had a cut almost all the way through it. That belt probably would not have lasted more than an hour or so. I now use Gates belts for both my water pump and alternator. They are more expensive than the Torreson belts, but you will immediately notice how much better quality they are.
One of the many things that will shorten, perhaps drastically, the life of an otherwise "good" impeller is sucking up grit into the your water pump. If you have any reason to believe that you've done so (i.e., gone aground, etc), best to check and/or replace your impeller. Sand or grit works like sandpaper moving at high speed if it gets into your water pump. Not only could it destroy your impeller, it could also damage or ruin your water pump. To the poster below who described a cut in his water pump belt, I had the same thing happen with an almost new belt I bought from Torreson. The belt was properly tensioned and the pulleys were in good condition. One day while checking the engine prior to a sail, I just happened to notice that my newish OEM belt had a cut almost all the way through it. That belt probably would not have lasted more than an hour or so. I now use Gates belts for both my water pump and alternator. They are more expensive than the Torreson belts, but you will immediately notice how much better quality they are.
Warren...
being and old sports car racer and former gear-head, I have the belts off the Yanmar sitting on the garage workbench for the next trip to the auto parts store for a good set or two of Gates replacements. Never lost a Gates belt in a race. Cranks, rods, clutches, overdrives, alternators...
being and old sports car racer and former gear-head, I have the belts off the Yanmar sitting on the garage workbench for the next trip to the auto parts store for a good set or two of Gates replacements. Never lost a Gates belt in a race. Cranks, rods, clutches, overdrives, alternators...
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