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Having owned my '76 M3 for 3 years, its embarrasing to admit I know more about the Andromeda galaxy than I know about the impeller(s) on my boat - and thus I seek information and guidance. The A4 is fresh water cooled with, what I believe, is a factory installed system rather than a Moyer add on. My question is this: how many impellers do I have and where are (is) they (it)? Can it (they) be replaced easily, and where would I find new ones. Thanks ....
Santeria
Mark lll Hull #626 - Mahone Bay, NS
Last edited by (2009-02-24 06:36:04)
Santeria
Mark lll ;Hull ;#626 - Mahone Bay, NS
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The Moyer Marine website archives is the best place to find out all there is to know about Atomic 4 sailboat engines. There are several great impeller threads there.
<a href="http://www.moyermarine.com/forums/index.php">http://www.moyermarine.com/forums/index.php</a>
A standard A4 has one impeller per water pump. In a freshwater-cooled engine (one fitted with a heat exchanger), there will be two water pumps, one pumping cold raw water to the heat exchanger and out the exhaust, and another pumping cooled antifreeze coolant from the heat exchanger to the engine. In a raw water-cooled engine, there will only be one pump, pumping raw water through the engine and out the exhaust.
Each pump has an impeller. Check out the archives at the MMI website for instructions, or purchase Don's excellent Atomic 4 service manual and accompanying notes. There is also a less detailed but good Canadian Atomic 4 manual available from an Ontario website (Seacraft Publications). Each pump has a plate that unscrews, revealing the impeller. The impeller slides off the shaft, but there can be tricks to this, depending on the model. Re-insert the new impeller and replace the cover plate, being careful not to pinch the o-ring. It's like riding a bicycle: a bit of a learning curve the first time, then it's drop-dead easy.
Impellers are standard parts at marine suppliers, but there are differences between models. See the archives at the MMI site.
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"New" 1974 C&C 27 Mk II undergoing refit
Last edited by (2009-02-24 19:53:20)
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1974 Mark II C&C 27
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I went throught the same questions when I got my Mk 1 two years ago and had some temperature problems. I researched through this forum and Moyer Marine, learned as much as I could about my engine and cooling system, them figured out how to replace the impeller.
If you have raw water cooling you will have just one pump (and one impeller). If you have fresh water (i.e. recirculating / antifreeze) you will have a second pump.
I have a main (recirculating) pump in the OEM location - starboard side, aft of and below the distributer and alternator. If you have a second pump it would be forward of that. Mine runs off the alternator belt although it could be further forward running off the flywheeel in another configuration. Access to either pump is difficult on the 27. You have to pretty much be inside the starboard lazarette to be able to work on it. The good news is that it is not that hard to do.
There are three possible brands of pump - Oberdorfer, Jabsco or Sherwood. The most common are Oberdorfer. The main pump will be an Oberdorfer (which was OEM) and there are only two possible impeller part numbers with most pumps taking the most common one). You can order them from Moyer Marine. My second (raw water) pump is a Jabsco, but from my discussions with other A4 owners, the Oberdorfer is more common. If a Jabsco, you can get the impeller from any marine store. The model number is on the back plate of the pump.
To replace the impeller, you will have to remove the back plate from the pump (there are 4 screws on the Oberdorfer, 6 on the Jabsco), pull out the impeller and shaft, slide on the new impeller, reinsert the unit then replace the cover plate and gasket. There are some good descriptions of the process (with pictures) in the Moyer Marine forum and some ither sites.
Good luck.
Greg Tokarz, Nepenthe, C&C 27 Mk1, Hull #73
Greg Tokarz,
Nepenthe, C&C 27 Mk1, Hull #73
National Yacht Club, Toronto
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Another important detail is to determine the direction of the rotation of the impeller inside the waterpump, then bend the blades accordingly when inserting the impeller. This ensures correct suction action by the impeller.
john w bienko
BLUE EYES __o_( )_o__
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there are some great add on's to make changing the impelors easier. One in particular is a cover plate, with thumb screws that won't fall into the bilge. Everything can be found on Don Moyers website. Good luck
Dana
Capricous Hull #599
Capricious Mark 3 Hull #599
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As the discussion has moved to add-ons, I hope I can be excused for repeating a warning about dealing with people who stand by their products. I wrote the following a few years ago as part of another thread on impellers.
"Towser used to have an A4 that had been retrofitted with a fresh-water cooling system that included a belt-driven pump for the sea water on the forward end of the block. This pump ate impellers and it was a real hassle to replace them. Accordingly, when I heard about the Speed Seal, I bought one for this pump (I think it was about $70). If you're not familiar with Speed Seals, they are a heavy brass plate with a groove for an o-ring machined in the face. Because the plate is so rigid, they can be held securely with just 4 knurled nuts that you can run up with your finger-tips. Now, instead of a major hassle, it was something I could do without looking at the pump.
So I bought one for the pump on the body of the A4 that pumps the internal coolant. Unfortunately, this one leaked enough to visibly lower the coolant level over 20 minutes running. I tried everything suggested by Speed Seal's owner to remedy the problem. He sent me a second plate to try. Same problem. Same diagnostics, no luck. Then the A4 died.
Well, the new engine has a pump too, so I thought a Speed Seal might be a good idea here. I called the Speed Seal guy and asked him, since the A4 plate never worked despite our best efforts, would he consider replacing it with one for my diesel? The answer: 'No.'
Since I had installed it, he wouldn't be able to sell it to someone else.
But it was only by installing it that I was able to find out that it didn't work.
Didn't matter - how could he run a company that kept delivering bits to people over and over again without getting paid? Forget it. End of discussion.
So if the discussion of impellers now ongoing moves you to consider a fast-change solution, consider this: Speed Seal scored one out of three overall, zero out of two for the A4. And Don Moyer of Moyer Marine, who has always been a friend to A4 owners (when I had a little issue with his A4 alarm kit, he worked on the issue and he solved it), has a similar product. His almost certainly works."
And if it doesn't, he stands behind it until it does work. What better can you ask?
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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I'm sorry about youre speed seal issues, but if you read my comment it was about a Moyer product.
Dana Marblehead Mass
Capricous Hull #599
Capricious Mark 3 Hull #599
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Actually, I think my comment broadly, if somewhat indirectly, supports your message - "Don Moyer is a good person to deal with for A4 add-ons," while adding the caveat that "Speed Seal is not a good company to deal with."
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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I would never steer my fellow 27 C&C members on anything but a starboard tack
Capricous Hull #599
Last edited by (2010-01-04 07:57:04)
Capricious Mark 3 Hull #599
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