Westerbeke impeller issue

[sunluvr]

On my Westerbeke 27 engine (on an Aloha 34) I replaced the impeller sometime later in the season last summer before hauling the boat for the winter. At that time, I noticed that there didn't seem to be a lot of water coming out the exhaust some of the time. The impeller I pulled out had 1 of 6 fins missing. For the rest of the season, it seemed fine. Today when I launched my boat, I ran the motor for about 10 to 15 minutes, just driving it to its slip at low revs. The water temp gauge slowly warmed up to its normal operating temp of about 80C. After tying up I noticed that there was nothing coming out the exhaust except for a small amount of steam. The outside air temperature was about 7C and the lake water temperature was about the same. I shut it down after waiting another 5 minutes or so, to let it cool down for a while and then started it again. The same thing happened as it warmed up to 80C and stayed at that temp for about 10 minutes before it started creeping up closer to 90C so I shut it down. Again, there was only a small amount of steam coming out the exhaust, no water. After cooling down, I opened up the impeller and found 1 of 6 fins was missing, the rest of the impeller looked to be ok. This is my first wintering with this boat, prior to this, my only experience was with gasoline engines for about 30 years. It seems strange to me that an impeller with 5 of 6 fins remaining would not pump a drip of water. I have checked that there is no blockage from the water intake to the impeller. Any ideas or suggestions I can ponder while I wait for my 2 newly ordered impellers to arrive?

[Lepke]

I thought the 27 was a diesel? The missing fin is probably in your heat exchanger. I wouldn't run an engine with a damaged impeller. If the rubber is hard, it may not be making good contact with the housing. Besides the heat exchanger, the place where the raw water enters the exhaust could be clogged with rust or other debris. When repairing diesels for others, I often found multiple impeller pieces clogging the exchanger.

[sunluvr]

Originally Posted by Lepke

I thought the 27 was a diesel? The missing fin is probably in your heat exchanger. I wouldn't run an engine with a damaged impeller. If the rubber is hard, it may not be making good contact with the housing. Besides the heat exchanger, the place where the raw water enters the exhaust could be clogged with rust or other debris. When repairing diesels for others, I often found multiple impeller pieces clogging the exchanger.

yes, it is a diesel.. I am just pointing out that I have not had experience before either with diesel engines or engines with a heat exchanger..

[Gqdoggy]

Apologies if I’m doing this incorrectly. I’m a brand new boat owner and a new member to this forum. I’m having an issue with steam coming from my exhaust after I did an impeller change. Wondering if someone on here could point In the right direction as to how I can start a new post. Can’t seem to figure it out.

[sunluvr]

Once you are logged in, go to the forum you want to post in, and just below the header for the page on the left side there is a button 'New Thread'.. click on that and away you go you might also want to do a search first with some relevant keywords to find other posts about the same issue..


welcome to boating and the forum

[Compass790]

The cover clearance on raw water impeller pumps is critical. Don't know yr engine but make sure you use the gasket or o-ring supplied with the impeller. Too small a clearance & they destroy impellers quickly, too large a clearance & they don't pump. Lube the impeller when installing, ideally with glycerine , silicone grease or dishwash detergent. If the clearance is right you should get a few years out of an impeller tho they vary. We installed a strainer after the pump to sieve out any impeller bits
All this is assuming you have no blockages in HX or pump . Check those before installing the new one as Lepke said