Yanmar waterpump impeller

MSO sailor · #1 02-09-2013

i just bought a impeller for a Yanmar 1 GM diesel & its only about 1"-1 1/8"s ! Is that how small they are? And also how many do i need? from everything I've read it seems to be only one.
Also can i replace it right in the boat or does the WP hav to be removed( seems like it just has a cover over it with 3 bolts holding it on). Boat is under 24" of snow so i can't go look!lol
MSO

leogallant · #2 02-09-2013

Typically only 1 impeller to replace. First, close the seacock for the raw water intake to the pump. Remove the screws to the cap of the pump and you'll see the old impeller. Note the direction the vanes of the old impeller are facing before removing so you know which way to bend the the vanes on the new one when you put it in.

There are lots of great vids online and I believe MaineSail has an article on his website.

hillenme · #3 02-09-2013

If you have a 3GM you may have to remove it. Or create a tool to get out out, Nigel Calder shows how to do this in one of his books or articles...

hillenme · #4 02-09-2013

Should have read the whole post...you clearly have access to the impeller, easy job.

MSO sailor · #5 02-09-2013

Ok cool, but is the impeller very small?
MSO

chef2sail · #6 02-09-2013

Quote:

Originally Posted by MSO sailor

Ok cool, but is the impeller very small?
MSO

very small? compared to what... its not big and cumberson....also feel free to soap it up with dishsoap before reinserting the new one

Seaduction · #7 02-09-2013

Looks like this:

overbored · #8 02-09-2013

yes, it is very small about 1" and 1/2" wide. the pump is also held on with 3 bolts and is easy to remove but you will also have to remove the hoses. when was the last time the hoses were replaced, they are cheap and good insurance to replace every 5 years, impeller every 2 years.

Seaduction · #9 02-09-2013

There is also a paper gasket under the water pump removable cover that should be replaced as well. Its a good idea to purchase some of the cover screws as well since they are easily buggered up if they are 'frozen' tightly or if you happen to drop one into the bilge.

HUGOSALT · #10 02-09-2013

MSO you ask how many impellers you need, the answer
is just one...at a time.
You will be well served by keeping a spare on the boat, as these little buggers sometimes have a way of disintegrating at the most inopportune times!
Don't buy spare until you install and know the new one is correct
size as the GM engine series has several different water pumps with
different size impellers.
Assuming boat is new to you, so suggest that you might change
belts as well and keep old ones as spares.
Had both an impeller go and water pump belt break on same cruise
few years ago, with spares we didn't miss a beat and very
reassuring being self sufficient.