Just for information of all we had an engine overheat alarm last week on our 2GM20. Rather than risk engine damage we shut down and a friendly powerboat towed us about a 1/4 mile back to the vicinity of our slip. I removed the raw water cooling pump and discovered that the bronze sleeve inside the impeller had come unglued. This caused the impeller to remain stationary while the pump shaft and sleeve continued to rotate. Replaced the impeller and now carry a spare. The Yanmar mechanic whose shop is nearby said that he's seen this happen quite often. I don't know how many hours on the engine since the impeller was last changed. Seems to me that this may be a manufacturing flaw that needs to be addressed. Dave Winiker H31 "Champagne on Ice"
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Roy Mosteller
Happened To Me Too
The exact same thing happened to me several years ago with an impeller I purchased from my Yanmar dealer. It failed after only about 10 hours. Dealer readily gave me a replacement and acknowledged this was not an isolated problem. I now keep two spares on board and was also prompted to install a water temp gauge on my 2GM20F so I can monitor the water temp and not be startled if the alarm goes off. Yes, the alarm continues to be functional.
The exact same thing happened to me several years ago with an impeller I purchased from my Yanmar dealer. It failed after only about 10 hours. Dealer readily gave me a replacement and acknowledged this was not an isolated problem. I now keep two spares on board and was also prompted to install a water temp gauge on my 2GM20F so I can monitor the water temp and not be startled if the alarm goes off. Yes, the alarm continues to be functional.
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Sam Lust
Nooo---- It's an operator flaw
Dave --- it's just a silly piece of rubber. Rubber deteriorates. Put it in hot bronze and spin it around in salt brine and it's going to break apart, probably sooner than later. The concensus on this site seems to be that the impeller should be replaced after two seasons of use. As I recall an original equipment replacement impeller costs about $15. A new 2GM20 runs about $6000. without installation. Your choice. The failure was simply due to a lack of scheduled maintenance. This one can't be blamed on the manufacturer.
Dave --- it's just a silly piece of rubber. Rubber deteriorates. Put it in hot bronze and spin it around in salt brine and it's going to break apart, probably sooner than later. The concensus on this site seems to be that the impeller should be replaced after two seasons of use. As I recall an original equipment replacement impeller costs about $15. A new 2GM20 runs about $6000. without installation. Your choice. The failure was simply due to a lack of scheduled maintenance. This one can't be blamed on the manufacturer.
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Roy Mosteller
Not Trying To Be Argumentative
But - I reviewed my engine log and find I have had the raw water impeller fail two times on my 2GM20F during the past five years in the exact manner described by Dave. First time after 18 hours and second time after 10 hours. Both impellers were purchased from my Yanmar dealer and had been installed only several months each time. I religiously change impellers anually and because of my experiences I keep two spares on board. I believe my Yanmar mechanic who says this is not an isolated problem. I am sure my two incidents were not caused by lack of maintenance as both impellers were relatively new. So, I hope others heed the advice to keep spare impellers on board. Anyone else had this problem other than Dave and me?
But - I reviewed my engine log and find I have had the raw water impeller fail two times on my 2GM20F during the past five years in the exact manner described by Dave. First time after 18 hours and second time after 10 hours. Both impellers were purchased from my Yanmar dealer and had been installed only several months each time. I religiously change impellers anually and because of my experiences I keep two spares on board. I believe my Yanmar mechanic who says this is not an isolated problem. I am sure my two incidents were not caused by lack of maintenance as both impellers were relatively new. So, I hope others heed the advice to keep spare impellers on board. Anyone else had this problem other than Dave and me?
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Marc Kraus
Speed Seal
There is an excellent product called Speed Seal which is a brass cover for the water pump fitted with a nitrile O ring and Knurled thumb screws. You can change out your impeller in 2 minutes with out having to dismount the pump or deal with the six 4mm brass screws or paper gasket. I've fitted 2 engines with this product and wouldn't sail without it. Practical Sailor has reviewed it and is impressed.
There is an excellent product called Speed Seal which is a brass cover for the water pump fitted with a nitrile O ring and Knurled thumb screws. You can change out your impeller in 2 minutes with out having to dismount the pump or deal with the six 4mm brass screws or paper gasket. I've fitted 2 engines with this product and wouldn't sail without it. Practical Sailor has reviewed it and is impressed.
Where these OEM impellers?
Dave/Roy: Do you know if these where OEM impellers or something like a Jabsco? I know that there was a bad batch of these sometime in the last couple of years. We have not heard of any problems again recently until now. It is my feeling that these things can last 5-10 years or fail almost immediately (based on previous reports). Obviously nothing wrong with changing every year. But maybe if these new ones fail that quick, changing out to a new one that often is not the answer. We sometimes motor for 8-10 hours getting to the bay. Now wouldn't that be a fine time trying to do this out in the middle of San Pablo bay. Mark's suggestion of the speed seal may be the ticket. I have one and have not installed it yet. Just waiting for my next impeller change out.
Dave/Roy: Do you know if these where OEM impellers or something like a Jabsco? I know that there was a bad batch of these sometime in the last couple of years. We have not heard of any problems again recently until now. It is my feeling that these things can last 5-10 years or fail almost immediately (based on previous reports). Obviously nothing wrong with changing every year. But maybe if these new ones fail that quick, changing out to a new one that often is not the answer. We sometimes motor for 8-10 hours getting to the bay. Now wouldn't that be a fine time trying to do this out in the middle of San Pablo bay. Mark's suggestion of the speed seal may be the ticket. I have one and have not installed it yet. Just waiting for my next impeller change out.
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Roy Mosteller
Yanmar Was My Source
Steve - Both of the impellers that failed on my 2GM20F came from my Yanmar dealer in San Diego (PacWest Marine). I don't know whether they were packaged in a Yanmar container. The first was actually installed by a PacWest mechanic and I installed the second one. Both failed because the rubber separated from the shaft. My last failure was in September '97 and I have had no problems since then. I like to replace impellers annually because of my experiences and as I said in my original post this prompted me to add guages so I can monitor water temp and oil pressure.
Steve - Both of the impellers that failed on my 2GM20F came from my Yanmar dealer in San Diego (PacWest Marine). I don't know whether they were packaged in a Yanmar container. The first was actually installed by a PacWest mechanic and I installed the second one. Both failed because the rubber separated from the shaft. My last failure was in September '97 and I have had no problems since then. I like to replace impellers annually because of my experiences and as I said in my original post this prompted me to add guages so I can monitor water temp and oil pressure.
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