Replacement of R-21 Impeller

[markm]

I have a 2005 R-21. Everything runs well engine wise. Is it standard to replace the impeller when everything is working fine? Or should I leave well enough alone?

Thanks

Mark

 

[rt11002003]

I have mixed emotions. Ususally, my attitude is "don't fix it, if it ain't broke". However, some things will invite a worse situation, or even disaster, if they should break. Impellers, when they break, present more problems. At a minimum, one will have reduced water flow and possible overheating. That could happen at a very bad time. Bits and pieces could clog the heat exchanger, also causing overheating.

That's one item I suggest changing at least annually.

Gene

 

[markm]

Gene,

Thanks for the post. Is this a "do it yourself job". I know there have been many post on this subject, but I wanted a 21 opinion. The engine is the same on the R-21 and the R-21 EC.

Thanks

Mark

 

[walldog]

Not sure about the 30hp, but on the 18, it is not a very hard job. Removing the pump is straight forward. Once removed, it is very easy to take the cover off and replace the impeller. Just be sure that you angle the blades correctly, an easy task if the old impeller is not destroyed. In my case, I had to figure out which way it turned in order to angle the blades properly. Gene is correct about the impeller coming apart and possibly clogging system, but the sea strainer should catch any pieces big enough to cause problems.

You can find a Yanmar manual for your engine here
Cannot make the link work. Go to this post and try the link

viewtopic.php?f=7&t=520

This should be close enough

http://www.yanmarmarine.com/index.cfm/g ... t-engines/

mine shows a nice exploded view of the seawater pump and impeller.

 

[walldog]

This is a direct link to the manual that I am using.

http://www.yanmarmarine.com/theme/yanma ... 1JAN09.pdf

 

[RProffer]

Let me try this again. I posted once and it appears it did not take.

Ranger has used two types of engines in the R21/R21-EC tugs. Initially they used the Yanmar GM series engines, and then changed to the YM series engines when Yanmar discontinued the GM series.

In the GM series engine, the service manual says to inspect the impeller after 500 hours and replace it after 1000 hours. On Tugnuts/Cbrats, some people had problems with the impeller failing causing mucho damage. Many people started replacing the impeller annually as a safety precaution - an impeller is a lot cheaper than a burned up engine.

In the YM series engine, the service manual says to inspect the impeller after 250 hours or annually, and replace it after 1000 hours or 4 years.

To comply with your engine warranty, you need to comply with the scheduled maintenance requirements in the service manual as a minimum. You can always do the scheduled maintenance earlier that required. Be sure to log any maintenance performed.

 

[rt11002003]

Mark, replacing the impeller is an easy do-it-yourself task, when done under ideal conditions (correct tools, parts present, boat stable, etc.). On the YM series engines that pump is out in the open , forward on the starboard side. Really easy to get to to work on. Be careful and don't drop any of the screws, bolts, etc. With my luck everything always falls into the bilge. Recovering things from there can be a nightmare. I suggest placing a large shop rag under the area where you're working to catch dropped items.

If one inspects the impeller as one should, then one will know which way to bend the vanes when the time comes to replace it. If inspections haven't been done, then with luck, the impeller will be intact the first time one opens the pump and again one will see which way to bend the vanes. I always lubricate the new impeller with a solution of dish washing soap and water. And, I make sure that as much raw water as possible is present aft of the pump. Running the impeller when dry is a no no.

Gene

 

[abcandjrc]

Two hints: I have a large cork that I put in the limber hole in the bottom of the engine bed to keep screws and such from disappearing into never-never land when doing engine maintenance. I keep oil-soak pads there, too, giving me an extra level of protection. (Some still get away somehow, but this is a good first step.)

I also took an electric engraving tool and carved the direction of rotation into the cover for the raw-water pump the first time I pulled the impeller. If your memory is as bad as mine, you might pull the impeller, do something else in the meantime, and then forget which way to put it back. This quickly solves the puzzle for you. For some inscrutable reason Yanmar seems to have stamped the cover with arrows indicating rotation in both (??) directions. A magic marker should suffice if you don't have an engraver. Just keep it updated as needed if fuel or antifreeze begin to wash it away.

One of the first things I did was purchase some spares which I keep on board. Among them are an impeller and an O-ring for the raw-water pump cover. Cheap insurance in case you have to do that while afloat sometime.

 

[trailertrawlerkismet]

You're getting a lot of great advice from your fellow Tugnuts. As someone pointed out the impeller is a rather easy change when done in an ideal setting, especially after you've had experience swapping one out. A couple additional thoughts would be to always carry a spare impeller on board, they'll go out when you least want them to. Second would be to read up on how to change yours in your manual then try and change one at the dock for experience. If you're uncomfortable changing one out ask a friend who has experience or hire someone to do it and watch. One trick I've learned along the way is to secure a zip tie to the impeller blades thereby holding the fins down in the proper position, it makes it easier to slip onto the impeller shaft. It's like riding a bike, once you've done it it becomes second nature.