Raw Water Pump Failure

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G

gozer7

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Joined
Mar 21, 2009
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16
Fluid Motion Model
C-24 C SE
Hull Identification Number
USFMLT2129K8
Did I do something wrong? Last winter I filled the raw water side with RV anti freeze by opening the little cap and sucking the anti freeze out of a bucket until it ran out the exhasut port. Today on its first outing since winter storage the engine over heated after running for less than 20 minutes. I later found the raw water pump impeller shredded. I will order another one it's a Johnson 810 B-1..and a spare. The boat is a 2009 R21 E. Any thoughts???
 
These little rubber bladed impellers can be very sensitive if no water is present. It is possible that the impeller "ran dry" while the RV solution was being sucked into the engine and the impeller broke apart during the process or was so weakened that when the engine was run on your first day, it just gave way. If the engine was already warm during the winterization process, the impeller would not last long, like seconds, if there was no water to it.

Introducing the RV solution while the engine is sucking water and allow the process to happen gradually would be my only suggestion.
 
My way: I remove the cover of the raw water strainer... Close the seacock and fill the bowl with RV fluid.. Then I start the engine while another person keeps the strainer filled with fluid by slowly pouring it in as the engine sucks it out... WHile he is dong that I walk back and watch the exhaust... When the water in the muffler has been replaced by enough RV fluid so that the exhaust is good and pink, I go shut the engine down...
 
Ummm, after posting the above I noticed you were talking about an R21, so my advice may be all wet as I have not seen one...
 
Not uncommon to loose a impeller with low hours. Mine was missing a vane at my first service but in December it did not show a problem. Always leave the transmission in neutral when inspecting the prop as any backward motion will wipe out the vanes too! They are fragile. Easy to get from Fisheries Supply in Seattle. I will have some aftermarket Gates part numbers for the belts as soon as I put them on. I thought I had the correct parts but when I wanted to change them out I found they were a bit tight so went up one size. Bob Heselberg in Eatonville Wa
 
Denny-o, Question. Do you do this RV fluid transfer when boat is out of water? Kit
 
I have done it out of the water. My first winter I wasn't able to use the boat. Hooked up the hose to the plastic raw water fitting and dropped the other end into the antifreeze solution. Ran the engine until the exhaust liquid was pink.

My raw water system was full of water before this procedure. I had closed the raw water thru hull when shutting down, trapping water in the system.

Gene
 
Yes, I do it with the boat on the trailer... As long as the person pouring the antifreeze does not let the bowl go dry the impeller doesn't know the difference... I do this at home on the cement pad in front of the workshop, so the minor amount of RV fluid being discharged onto the cement is not an issue...

For running the engine for other reasons than winterizing, it would be easy enough to clamp the end of a garden hose so that it discharges into the raw water bowl, adjust the flow rate so that it matches or slightly exceeds the engine's pumping rate, and perform engine maintenance or a tune up, or to simply to get the oil warm for an oil change, while comfortably on the trailer or on the hard... Of course, you will be dumping exhaust water and bilge pump discharge onto the ground, so you have to keep that in mind - probably the grass would appreciate it...

Be aware, for those immediately envisioning a Tee fitting in the raw water hose to connect the garden hose directly to the raw water pump, that if you force water INTO the engine -either without the engine running or in excess of the impeller's pumping rate - that you will flood and back flow from the muffler into the engine with disastrous results being very likely...
 
I do the same thing with my R25 each fall. Boat on trailer, hull valve closed, bowl cover removed, warm up engine, change the oil, restart engine and put in the pink stuff. The only shortcoming so far is that it is easy to just let the bowl overflow to bilge while the engine is at idle. However, if you attempt to increase the engine RPM to warm faster the raw water pump will quickly take more water than you can provide in bowl. Takes a long time to warm engine at idle.
 
Suggestion-
I winterize the raw water coolant system with the boat on the trailer. First, I warm the engine and change the oil while the boat is in the water at the marina. The boat is immediately put on the trailer. I then loosen the small drain caps on the bottom of the sea strainer and the muffler. When they are emptied the caps are replaced. The thru hull valve is then closed. Remove the top of the sea strainer and fill with anti-freeze. Just in front of the strainer, in front of the raw water supply I have installed a "T". I connect one end of a short piece of hose to the "T". The other end of the hose is in a 5 gallon bucket of anti-freeze. My assistant holds another bucket under the exhaust port to catch coolant as it exits Tuggin Aweigh. I then start the Yanmar. The anti-freeze is pulled thru the heat exchanger, fills the muffler and empties into the bucket. With a tester I check the strength of the exhausted coolant. If the coolant in the bucket tests minus 20 I feel comfortable the engine is protected.

Frank and Pam
Tuggin Aweigh
 
Wow, great replys and thanks for the advice. See you in the San Juans this summer and will always hail a Ranger!

Mike & Pam
 
Got to come clean on this. Looks like I closed the salt water sea cock at the end of last season, and didn't remember to open it . No wonder it tore up the raw water impeller. The replacement seems to be working, but makes some hissing noises and the bildge pump goes off every now and then. 😉
 
I suggest that you pay attention to the hissing noises and why the bilge pump is cycling. There should not be hissing noises and the bilge pump running means there is water to get rid of. There may be other causes, but I would first look at the seal between the impeller cover plate and the engine block. That o-ring rides in a groove and provides the seal to the pump chamber. If that o-ring is not doing its job, air will leak in and out of the pump chamber, thus the hissing noise, and water water will be pumped into the bilge.

I would take a light and look and feel the bottom of the impeller cover while the engine is running to see if it is leaking.

I, too, have run the engine with the intake water valve closed. Not only did I toast the impeller pump but also parts of the water exhaust system melted due to the overheated. An expensive but remembered lesson.
 
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