Impeller question

[Stevelack]

After years of engine-less dinghy sailing we've recently purchased our first boat with a diesel engine, in preparation for moving aboard and full-time cruising. The boat is still in the yard and we're about to launch it in a couple of weeks.

In preparation for the big event I thought I should order a spare impeller. When I opened the impeller pump cover this is what I saw.



When looking at the datasheet on the pump, and on replacement gaskets, service kits and impellers it seems like there is an extra piece in my housing that should not be there.

I am a complete noob when it comes to engines and am having a survey done next week. (This was a donation boat and was so inexpensive that I opted to buy it without a survey first).

I was wondering if anyone could tell me if the attached photo looks right, or is there something that may need further investigation before trying to run the engine. Or, if I just buy a new impeller, will it just slip into the unit, as it's supposed to.

Thanks for any advice!

[Uncle Bob]

Originally Posted by Stevelack

After years of engine-less dinghy sailing we've recently purchased our first boat with a diesel engine, in preparation for moving aboard and full-time cruising. The boat is still in the yard and we're about to launch it in a couple of weeks.

In preparation for the big event I thought I should order a spare impeller. When I opened the impeller pump cover this is what I saw.



When looking at the datasheet on the pump, and on replacement gaskets, service kits and impellers it seems like there is an extra piece in my housing that should not be there.

I am a complete noob when it comes to engines and am having a survey done next week. (This was a donation boat and was so inexpensive that I opted to buy it without a survey first).

I was wondering if anyone could tell me if the attached photo looks right, or is there something that may need further investigation before trying to run the engine. Or, if I just buy a new impeller, will it just slip into the unit, as it's supposed to.

Thanks for any advice!

Relax, it is exactly as it should be. Its there to force the water out of the outlet and then the implpellor sucks more in the inlet as it spins.

[Stevelack]

Thanks Uncle Bob! I guess I'm over thinking this. I'll just order a replacement impeller and have it around for when I need it.

[nigel1]

That bit is the Cam, and it should be there, if it's not, the pump will not generate suction.
The impellers are not the easiest thing to remove, if you prise them out, be careful not to damage the face of the pump.
Tip for replacing, liberally apply silicone grease to the impellor and the shaft, and then fit a tie wrap around the impeller and tighten to flatten down the vanes. Note the direction of the vanes on the old impeller and fit the new one with the vanes in the same direction.
Keep the tie wrap on until you have the impeller about half way on the shaft, the tie wrap will slide off as you push the impeller into place.

[transmitterdan]

In looking at the picture I think you would be wise to replace this impeller. You probably don't know how old it is and it looks to be more than a couple years. You don't want to be replacing an impeller on a dark and stormy night. Also, when impellers fail they don't give any external signs. Pieces fall off and get stuck up inside the heat exchanger where it takes a lot of time to find them. Better to replace it now and write down the date and engine hours in a maintenance log. Then replace it every 2-3 years or however many hours the engine owner's manual suggests whichever is less.

[Tayana42]

Agree with Transmitterdan. That impeller needs to be replaced now.


S/V B'Shert

[Stevelack]

Just ordered a couple. I'll replace it before we splash and have a spare handy. Thanks for the replies. There is quite a bit to learn when going from a 16ft day sailor to a 38ft live-aboard!

[J Clark H356]

Coat the new impeller liberally with white lithium grease and then just twist it over the hole and it will go in. If you don't twist it, you will really have a hard time getting it to fit. A simple twist and it is in. Some people use the twist tie method as described by another poster, but I have never made that work. I spent several hours trying to replace one on my generator in 100 degree heat so I could get my air conditioner back on and never did. I tried a hammer, twist ties, screw driver, everything I could think of. When I got back to the marina the next day I got Wayne, the mechanic, to come put it in. He had it on in about 2 seconds! I asked him to take it out and show me again and he did again in two seconds. We took it out again, he explained you have to twist it, and I did it in 2 seconds. I've never had a problem since and have changed quite a few. Also, don't worry about the direction of the fins. They will get oriented correctly once the impeller starts spinning. If you don't believe me, put one in, finish installing with the cover back on and then start your engine. Stop the engine and take the cover back off and you will see they are all running the same direction.

I also would recommend you get a Speed Seal Life for your pump. It has a Teflon disk the the exterior side of the impeller rotates against. It reduces friction and heat and they last longer. It will run dry for 10 minutes before burning one up. ( I know from experience).




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[DougR]

Several of the responses here suggest using grease of various persuasions when installing the new impeller, but I suggest avoiding grease. A better lubricant to use is glycerine. These days most impellers are manufactured of materials which are harmed by petroleum based products, and engine manufacturers such as Volvo, Yanmar, Johnson Pump, etc include a packet of glycerine with the impeller. Short of glycerine, use dishwashing liquid.

DougR

[a64pilot]

I use dish washing liquid, but if your really stuck on grease, there is a soap based grease used for O rings on bigger pipes, petroleum will eat up most rubber, ever stepped in or gotten gasoline on your tennis shoes?
I think some lithium greases are soap based?

[transmitterdan]

Silicone grease (Superlube is one brand) is compatible with most rubber impellers.

[colemj]

Originally Posted by DougR

Several of the responses here suggest using grease of various persuasions when installing the new impeller, but I suggest avoiding grease. A better lubricant to use is glycerine. These days most impellers are manufactured of materials which are harmed by petroleum based products, and engine manufacturers such as Volvo, Yanmar, Johnson Pump, etc include a packet of glycerine with the impeller. Short of glycerine, use dishwashing liquid.

DougR

Every impeller I've bought in recent years comes with a little packet of glycerine.

Mark

[lancelot9898]

Note on your photo that some of those vanes are pointing in the opposite direction. Also I had trouble with using some sort of petroleum based grease in that vanes broke off within a week of installation. After that I always used dish detergent to lube.

[Lake-Effect]

Originally Posted by Tayana42

Agree with Transmitterdan. That impeller needs to be replaced now.

Just furthering my education: are you gents recommending impeller replacement because of something you see in the photo, or more because it's a new (to the owner) boat and the age of the impellor is uncertain?

Thanks

[BostonFlicka]

Hi Lake Effect,

A new impeller is "cheap" preventative maintenance. Do you have a Westerbeke? Im guessing because of the red paint.

Many impellers/pumps are made by Johnson pump. It is much cheaper to by the impeller kit from Johnson than it is if its branded "westerbeke". Check around the internet there are many sources for parts there is generally a few major ones that are worth a glance, forgive me if I violate forum rules but to name a few without bias Jamestown distributors, Defender marine, Hamilton Marine, Torrenson Marine and Fisheries supply.

Since it it a new to you boat there are a few other things that you should look at and I would hope that the survey will encourage it. As far as the cooling system goes you may have a a heat exchanger, these tend to get buggered up over the years with broken impeller blades and often times have a zinc that needs to be "Checked Monthly" per westerbeke. Also be sure to check all cooling hoses for cracks and rusted out hose clamps.

I wouldn't worry about the backwards facing impeller vane. When the diesel shuts down it may actually turn in reverse for a fraction of a second just as it stops.


There is a good resource online from a fellow that runs compass marine in Maine. Do a little googling and it should come up. Maine Sail How to articles.


Good Luck and happy sailing