Impeller broken blades

kloudie1 · Dec 27, 2014

Broken vanes on the impeller are usually caused by a flow restriction which could be on the intake side or the discharge side of the system. Verify full flow area from the through hull fitting, through the strainer, all hose to the pump; no weed or clams or old collapsing hoses or plugged strainer. On the discharge side, plugging in oil or coolant heat exchanger or in the little fitting that hooks the hose to the exhaust elbow. If the pump itself is above the waterline, a small air leak in the discharge piping can do this as the pump has to re-prime every time it starts. running for even a few seconds with the intake seacock closed can do this too.. Happy Hunting.

Bob 04 H260 · Dec 27, 2014

Claude always has good advice, nothing like the voice of experience.

I put a speed seal http://www.speedseal.com/SpeedsealLife/SpeedsealLife.html on our boat and so far very happy with it. I'm not suggesting this as a cure but once the issue is resolved maybe an improvement.

Bob

Don S/V ILLusion · Dec 27, 2014

What make impeller did you use?

Dan Johnson · Dec 27, 2014

Second Don's question...

as there has been reported impeller failures from one of the manufacturers over the past few years. With proper water flow, this could be the problem.

Mark48 · Dec 27, 2014

I guess I will pull my for spring commissioning. Had not heard of the failures. I have a very short run to open water so I don't get many hours in a year. Thanks for the alert.

BarryL · Dec 27, 2014

Hey,

The only time something like that happened to me was when I used a Globe 'run dry' impeller. After one season all of the vanes had cracks near the root.

I went back to the black impellers and no problems since.

Barry

Rich Stidger · Dec 27, 2014

I seem to remember that it was Globe impellers that were failing- a search on this site will turn up the correct info. 1000 hours is a lot. I have never seen a claim that any impeller will last that long. Unless there is a bearing failure that causes play in the impeller shaft, I generally get 200+ hours on my Jabsco impellers. I change mine about 200-250 hours or every other year which ever comes first.

Don S/V ILLusion · Dec 27, 2014

I'm curious - what manual recommends changing the impeller at 1000 hours?

Chief RA · Dec 27, 2014

Rich, Don: I have never heard of 1000 hrs either. I change my outboard ones every couple of years. Chief

Don S/V ILLusion · Dec 27, 2014

Akapeterc said:
It is in the Yanmar manual 1000hrs. I will definitely check min every service thou I am using Johnson impellers thanks for the info cheers

I have the same engine in our boat (4JH3b). If I am correct, the Hunter 44 has the same engine. After looking through the manual as well as the manual for other 4JH Yanmars, I can't find where it says that.

Can you point me to the specific reference?

Thanks

Alan Gomes · Dec 27, 2014

Don S/V ILLusion said:
I have the same engine in our boat (4JH3b). If I am correct, the Hunter 44 has the same engine. After looking through the manual as well as the manual for other 4JH Yanmars, I can't find where it says that.

Can you point me to the specific reference?

Thanks

Although this is for a different engine, I did find this in the Yanmar GM Series Operation Manual, p. 55: "Note: The seawater pump impeller must be replaced every 1000 hours or every four years, even if it is not damaged." The 1000 hr/4 yr. figure is repeated again on p. 58.

Seems like way too long to me! But that is what the Yanmar manuals says--to my surprise.

Don S/V ILLusion · Dec 27, 2014

Thanks for looking. That's one manufacturer's recommendation i will never follow.

Capt jgw · Dec 28, 2014

I've also had terrible luck with Globe impellers. If there's any wear at all in the pump housing, the things won't seal well enough to pump at all. I've tried them on three different engines, never got one to work. Went back to the black rubber ones and no problems.

Maine Sail · Dec 28, 2014

I winterize about 12 boats each year and also deal with water flow issues during the season. About 7 out of 10 boats I see have cracked or broken impeller blades within one to two years. Your impeller issues are not necessarily abnormal but it could mean a flow issue... Keep in mind that if you're in an area with high weed levels, Maine has lots of floating debris, partial flow restricting clogs can be quite common..

That said I have some owners who have gone 6+ years and the impellers still work but are really "limp" noodles. On most boats it takes about 5 minutes to change one but on some Yanmar's & Westerbeke's I curse the Japanese the entire time.....