A-4 water pump impeller replacement for salt water cooled... how hard is this?

Scott Abbott

Member III
I have been working on my Ericson 27 that I bought in February in Annapolis. I have gotten down to the last few items on my punch list in order to sail her two days back to the southern section on the Bay in Virginia (near Deltaville). The A-4 impeller replacement is now on the list. How hard is this to do? Boat hasn't been in the water in 3 years! The motor starts and idles, but can't really run the motor to see true condition until I get it in the water on Friday to sea trial. tips? Thoughts?

Glyn Judson

Impeller replacement.

Scott, Others will tell you specifically what to look for when replacing the impeller on your A-4 so I will share with you a cautionary tale. On two occasions in my sailing life and on two separate boats, coincidentally both E31's, the water pump failed to work when I knew the pump body and impeller were in good repair and the raw water intake path was clear. In both cases the culprit was an air lock. The simple solution was for me to remove the uppermost hose attached to the pump, elevate it to its fullest vertical extent and using a plastic tumbler, I filled it with water from the galley sink. I placed my thumb over the end of the now full hose and in one movement, attached it with haste to the pump barb. In both cases that's all it took and the pump instantly came back to life (check the exhaust flange for acceptable water flow as proof). With your boat having been on the hard, there's every chance that your hoses and pump could have developed an air lock. You now know the work-around for that. As a matter of fact once you get your boat in the water, why not just fill the hose from the start so you can check that worry off your list? Good luck, Glyn Judson, E31 hull #55, Marina del Rey CA


Member II
I can't speak to your particular boat either -we have a 35-2. I would though advise when you do this job, and it is easy to do, you purchase a replacement back plate from Moyer Marine that has the furled knobs rather than screws. It makes it a much simpler job and it is what changed it from an 'I dread this' to a 'OK it's the second year, time to do it again' job.


Walter Pearson

Member III
Even all E27s are not all alike in that quarter berth/engine area, but with mine, it has always been easier to do water pump work with the pump removed. Usually, the inside bolt is not fun to get back in, but you can make an extension bolt to make things easier. From my notes, I used a standard, 3/8-16 by 3 1/2 in. long bolt and ran a nut up to the unthreaded shank portion where it remains jammed. Then the bolt head extends beyond the water pump and you are not operating by feel only.

I've gone several years on impellers and never had one actually fail - maybe just some visual wear marks. Granted, my season is short and not much engine time. The last time I changed, I went with the silicone impregnated (bluish) one which are supposedly able to be run dry without failing. I'm not going to test that feature, but the last time I inspected it, there were no visible wear markings. (This is all based on experience with late model Atomic-4 with Oberdorfer pump with increased output cam.)