Raw water pump surprise

[Russell]

The cool temperatures and rough seas from the nor'easter this weekend gave me the opportunity to change my raw water impeller. I have been meaning to do it since purchasing the boat last fall but the previous owner's records show that he changed it less than 200 hours ago and there have been no problems. To my surprise the impeller looked like the ones in manuals described as catastrophic failure. Two vanes were missing and others were cracked. Not only did I recover the two missing vanes but 5 more pieces from previously failed impellers. Most of them were trapped in the pump outflow grid but one made it to the front of the transmission oil cooler. I just do not see how the engine maintained operating temperature under these conditions. It must be way over engineered for cooling. Another surprise the next day was all the bruises on my arms from shoving them into the inaccessible places to reach the pump.

[N4QC]

Russ:

Good pick up...

What engine are you running?

Thanks,

[Mariner]

Gosh. We're pushing 400 hours on our engine and I'm sure it's the original impeller. I will be inspecting it at the earliest convenience.

[Russell]

Joe, I have the Cummins 6BTA at 250 HP. The interesting thing is I put off looking at this boat for many months because I thought that was not enough horse power. Most Albin 28's have 300 HP engines. But the broker took me for a test run and we cruised at 18 knots turning only 2300 RPM and mowed down the Chesapeake chop like it wasn't there. This engine has turned out to be the best thing about the boat.

[Pitou]

A good rule of thumb is to replace the raw water impellar every other year. Many times when inspecting an impellar by only removing the cover plate you will not see any damage, but when removed, the cracks will be evident and the vanes will not open up. Just make it routine and your engine will run cooler ( ) and you will not be looking for loose pieces.

[Veebyes2]

Coming up on 12 years old, our 32 is about due for a good overhaul. The raw water pump has been going for 3 seasons, about 250 hrs, with regular short runs on the hard with a hose in the winter. Still pumps well. Part of the regular startup checklist is to look over the transom to be sure water is flowing.

[Capt Paul]

Interesting hearing about how often you all change your impellers. It may sound like overkill, but mine is changed every 100 hours along with the oil.

Paul

[DougSea]

Interesting hearing about how often you all change your impellers. It may sound like overkill, but mine is changed every 100 hours along with the oil.

Paul

Given the incredible PITA that changing an impeller would be in an on the water "situation" I'm planning on changing mine out each Spring during commissioning. I agree it's probably overkill but it's a simple component that can just wreak your whole day - especially with a single engine. I view it as cheap insurance.

Like Doug (Veebyes) I also do a quick check on each startup to make sure I'm pumping water.

[Mariner]

It's not overkill to change your impeller annually. We've done so on all our previous boat and have just been slacking on this one.

[g.spier]

My engine overheated this weekend, not sure if barnacle growth or need new impeller??? Was it difficult to replace the impeller?? I am relatively mechanical.

[Pitou]

Here is a thread on impellar replacement.
http://albinowners.net/aog/viewtopic.ph ... t=impellar

[Russell]

If you have the 250 hp Cummins changing the impeller is not very difficult. To get better access release the struts on the engine box and tilt it all the way aft. The impeller came off with the housing as the manual said and I found it easier to put the new one in the housing rather than on the shaft as they recommend. The shaft key was on the top so I just aligned the impeller in the housing and slid it on. The hardest thing was loosening and tightening the bolt on the inside next to the engine block where there is little room to move a wrench.

[Veebyes2]

This was my impeller surprise Sunday morning. Well, not a total surprise. I have had suspicions about my impeller ever since launch last month. I check raw water outflow at every startup & noticed a decrease in flow. Most of the time we cruise at 1400 to 1600rpm. The temp has been slightly above normal. Friday we ran it up to speed for a bit. The temp went to over 200. The overheat buzzer came on. We slowed down & the temp returned to about 165. All this did was confirm the suspicion. The 3, maybe 4, season old impeller was due for a change. Didn't expect it to look as bad as THIS!. All the bits & pieces were found in the oil cooler front end.



Change your impeller every 2 or 3 years or after 400 hrs, whichever comes first.