Has anyone changed out the impeller on a 376? Once I got the right wrench (shorter one), getting the cover off was fairly easy.....but I could not get the impeller out....not enough room between the impeller and the starter for my big fingers or any tool I had in my kit. Thought about using a needlenose pliers with a 90 degree bend in the jaws but unfortunately they were in my tool kit at home. Anyone have some "tricks" or tools to make this job easier...going to have another go at it in a couple days.
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I Have
Take off the Alternator. If you are lucky you will not need to disconnect the wiring. Undo the 4 bolts and remove the cover. Take a blunt screwdriver and boldly lever the impeller out. Mine came quite easily with no damage whatsoever. Fit a new one using a little lubricant on the vanes. Keep the old one for a spare. In readiness for next time extend the two holes in the cover downwards to make them into open slots so next time you will not have to take out the two lower bolts. These are the awkward ones to fully undo and get back in again. Lastly I e-mailed Yanmar to enquire what service life they give the impeller and, 9 months later, am still awaiting a reply. My last Yanmar had two impellers in 17 years but the "experts" say they need changing once a year. Of course the engine will be red hot when you discover there is no cooling - not a good time to have to work on it. Good luck.
Take off the Alternator. If you are lucky you will not need to disconnect the wiring. Undo the 4 bolts and remove the cover. Take a blunt screwdriver and boldly lever the impeller out. Mine came quite easily with no damage whatsoever. Fit a new one using a little lubricant on the vanes. Keep the old one for a spare. In readiness for next time extend the two holes in the cover downwards to make them into open slots so next time you will not have to take out the two lower bolts. These are the awkward ones to fully undo and get back in again. Lastly I e-mailed Yanmar to enquire what service life they give the impeller and, 9 months later, am still awaiting a reply. My last Yanmar had two impellers in 17 years but the "experts" say they need changing once a year. Of course the engine will be red hot when you discover there is no cooling - not a good time to have to work on it. Good luck.
376 Impeller Access
A Yanmar mechanic recommended turning off all dc power then removing the two bolts holding the starting motor and just lowering it out of the way with the cables connected. This gives plenty of aft space to remove the cover and the impeller. I used an extension and socket to remove the starter bolts working from forward of the engine (mine were very stiff). I have a 75 degree plier to pull out the impeller. My effort was replacing the new one. I applied teflon grease and I had to use a wire tie around the center to hold the vanes in the in the right direction while inserting. I slipped the tie off as I seated the impeller. There may be a better way but it worked. Also I did this when I changed alternators; so I also had that out of the way. I noted no wear on the original 300 hour 4 year old impeller. I agree I'd hate to do it in a seaway so I suggest testing your approach in the marina and also maybe we'll share some idea how often to do it.
A Yanmar mechanic recommended turning off all dc power then removing the two bolts holding the starting motor and just lowering it out of the way with the cables connected. This gives plenty of aft space to remove the cover and the impeller. I used an extension and socket to remove the starter bolts working from forward of the engine (mine were very stiff). I have a 75 degree plier to pull out the impeller. My effort was replacing the new one. I applied teflon grease and I had to use a wire tie around the center to hold the vanes in the in the right direction while inserting. I slipped the tie off as I seated the impeller. There may be a better way but it worked. Also I did this when I changed alternators; so I also had that out of the way. I noted no wear on the original 300 hour 4 year old impeller. I agree I'd hate to do it in a seaway so I suggest testing your approach in the marina and also maybe we'll share some idea how often to do it.
Forceps
I had difficulty getting the impeller out on my 376 until I remembered that I had a pair of medical forceps in my tool bag. They have a 45 degree slant like some needle nose pliers, but they also lock when you clamp down. Plus, they're light and easy to work with. After a couple of tries, the impeller slipped right out. By the way, I didn't remove either the alternator or starter. The forceps had just enough room to do the job. Hope this helps.
I had difficulty getting the impeller out on my 376 until I remembered that I had a pair of medical forceps in my tool bag. They have a 45 degree slant like some needle nose pliers, but they also lock when you clamp down. Plus, they're light and easy to work with. After a couple of tries, the impeller slipped right out. By the way, I didn't remove either the alternator or starter. The forceps had just enough room to do the job. Hope this helps.
%90 needle nose
yanmar recommends using %90 needlenose. just did mine and had no problems. no need to undue anything else but the cover. in some instances where water has been left in the system for to long and the impeller hasn't been changed in a while it could get frozen on the shaft which would mean a housing unit replacement
yanmar recommends using %90 needlenose. just did mine and had no problems. no need to undue anything else but the cover. in some instances where water has been left in the system for to long and the impeller hasn't been changed in a while it could get frozen on the shaft which would mean a housing unit replacement
Impeller removal
Some comments on 376 impeller replacement after taking the Mack Boring two day hands-on course. First, you have to remove the starter. Second, use right angle needle nose pliers rather than prying with a screwdriver to avoid damaging the housing. Third, they recommend taking the impeller out for the winter if you are not using the boat (store it in olive oil and use the same impeller in the spring if you don't see any damage). Otherwise the impeller vanes may dry out and/or get stuck to the housing which could cause damage to the vanes when the engine is started in the spring. Annual removal also keeps the impeller from getting corroded to the drive shaft making removal more difficult when you do get around to it. I don't recall any guidance on how long the impeller should last. I have found that a rather large mirror articulated on the end of a telescoping shaft to be a very useful tool when changing impellers on the 376. The easy way (?) is to replace the entire pump assembly. This is straightforward if you first prop up the corner of the engine and remove the engine mount and mounting bracket as a single unit. You can then get at the water pump mounting bolts.
Some comments on 376 impeller replacement after taking the Mack Boring two day hands-on course. First, you have to remove the starter. Second, use right angle needle nose pliers rather than prying with a screwdriver to avoid damaging the housing. Third, they recommend taking the impeller out for the winter if you are not using the boat (store it in olive oil and use the same impeller in the spring if you don't see any damage). Otherwise the impeller vanes may dry out and/or get stuck to the housing which could cause damage to the vanes when the engine is started in the spring. Annual removal also keeps the impeller from getting corroded to the drive shaft making removal more difficult when you do get around to it. I don't recall any guidance on how long the impeller should last. I have found that a rather large mirror articulated on the end of a telescoping shaft to be a very useful tool when changing impellers on the 376. The easy way (?) is to replace the entire pump assembly. This is straightforward if you first prop up the corner of the engine and remove the engine mount and mounting bracket as a single unit. You can then get at the water pump mounting bolts.
anti-seize
A little hint to make it easier to remove the impeller next time: coat the impeller drive shaft with anti-seize grease before installing the replacement impeller. Slick.
A little hint to make it easier to remove the impeller next time: coat the impeller drive shaft with anti-seize grease before installing the replacement impeller. Slick.
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