Water Pump Questions

[gregt]

I have a 1971 C&C 27 with a late model A4. Because I have had trouble starting recently, I shut off the raw water intake when I cranked the engine. I usually open the seacock right away but got distracted by my passengers (a hat dropped over board, children nearly falling overboard, etc.). Basically, the motor ran for several minutes without the intake open and I think the impeller is destroyed. I have owned the boat for less than a year, and am not sure where everything is, so I located and opened up the water pump (antifreeze cooled) and the impeller was fine. There is a second water pump, connected to a heat exchanger that is connected to the through hull which I could not check without some more tools.

A couple of questions:
1. the water pump which looks like the original (located just forward of the shift linkage) had a thick brass cover but no gasket. After checking the impeller, I screwed ithe cover back on and didn't see any leaks. Does this sound OK?
2. the second (raw water) water pump (forward of the other) had a round cover with 6 screws. I think it says Jabsco on the cover but I couldn't tell for sure without the ability to bend by neck 90 degrees. Would this be the pump with the damaged impeller?

Thanks in advance for any insights.

Greg

[David Masury]

I can help you here... I have a C&C 27 (1975)... most of them came equipped with fresh water cooling.... they have a heat exchanger thus the two pump setup as you described.

First, since you have (should have) antifreeze in the fresh water side, which includes the engine and through the heat exchanger... you can run the engine without raw water for several long minutes and do no damage... it does take a while for the engine to heat up all the coolant.

Second, your raw water pump is the delicate one in this setup.... check the impeller on this pump. The replacement is available at most marine shops...lubricate it with some water pump grease when you install it.

I changed my raw water pump to the one that is sold here on Don Moyer's online shop... it uses the same impeller that the engine water pump uses and that is a plus when you shop for your onboard repair kit.

Best of luck

David

[gregt]

Thanks David. This confirms what I thought. Yes there was coolant in the fresh water pump. From the looking at the Moyer catalog, it looks like I have an Oberdorfer fresh water pump. However, I checked some marine web sites and it looks like I have a Jabsco raw water pump. I searched around the lockers on the boat and found a bag with some spare parts including a Jabsco impeller. I now just have to get a long screw driver as access to the pump is very difficult. Hopefully, I'll have the impeller replaced soon.

[Kelly]

In regard to your gasket question: the desired result is to have no leaks coming from the water pump. If this is your case with no gasket in place, then why not? This would just imply that the mating surfaces of your pump and cover are very flat and clean.

If it were me, I would keep a gasket or a sheet of gasket material on board, just in case.

Kelly

[marthur]

Here's a hint when carrying gasket material: every time I use or replace a gasket I trace it on your roll of gasket material. Then if I need a gasket and have destroyed the old one, I can cut it out and have a perfect fit first time.

[David Masury]

GregT... replace the screws with brass bolts... it is easier to get a small socket wrench in behind the raw water pump than a long screwdriver...

David

[gregt]

Thanks for all the input.

Re the lack of gasket - I had assumed I had a cover with an o-ring, although it is the first time I've had it off and I don't actually remember seeing an o-ring. I have ordered a gasket from Moyer Marine, so I will have one on hand. I like the idea of the gasket material and tracing the gasket before installing. Sounds like a great idea. I also like the idea of using bolts instead of screws. Especially to replace the slot screws which are evil things.