# Changing A Raw Water Impeller (How To)



## Maine Sail (Jan 6, 2003)

Hi All,

I just changed my impeller, second one this season, and this time I finally remembered to bring my camera.

I've noticed a string of overheating threads recently popping up here and on other forums so I thought this new photo based article may help some who are not totally familiar or comfortable with the task.

Changing A Raw Water Impeller


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## sailingdog (Mar 19, 2006)

Nicely done.


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## brianontheroad (Jun 9, 2008)

*couldn't ask for more!*

Great post/article -- especially since I have the exact same impeller/water pump system on my Westerbeke 27 that I'm going to have to replace tomorrow


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## camaraderie (May 22, 2002)

Excellent as usual Halekai! Thanks.


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## Pamlicotraveler (Aug 13, 2006)

> As I said this job is very, very easy. If you can change oil or an air filter or clean a blender after making frozen "chick drinks" you can change an impeller.


Halekai,

Your illustrated guides are very helpful. Really good. (did you do the stuffing box illustration a while back? You must have. I have saved it and used it)

With the impellor I have avoided changing mine on my Yanmar 4jh because it seems so inaccessible. There is no way you could take pictures like what you have here. I am certain I would drop one of the screws for the plate, or probably the plate itself, into the bilge and that "20 minute job" would ruin a sailing weekend or end up in me utilizing my unlimited Sea Tow policy

I have a spare impeller and the tools to change it, ie bent needle-nose pliers etc, and I think I can do it when I need to. But I really wonder why Yanmar puts the impeller case on the backside of the pump since it considered a maintenance item. It has to be done by feel - at least I don't have any mirrors that would work.

Anyway...thanks for the great explanation and illustration.


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## T37SOLARE (Feb 1, 2008)

Halekai,

Another GREAT post, thanks!

Pamlicotraveler,

My raw water pump is also not the most accessible, and with my eyesight and bad back, changing it in a seaway would be next to impossible. This past winter I retrofitted the cover with a 
 Speedseal  and I am very happy with the results.


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## chuck5499 (Aug 31, 2003)

SoulMates is a Jeanneau DS40 and has a Yanmar JH4 engine - maybe the issue is not yanmar but the engine access the boat mfg gives you - Jeanneau gives great access (at least i have it) and changing the impeller can be done without a lot of trouble - 
i would suggest that you do it at the dock before thinking you can do it at sea - it took me a while to figure it out at the dock but now i know i can do it at sea - may not be easy but i will have the confidence that i can do it - I did use a wire tie to get it in place and once i figured that out it was a breeze - 
just my thoughts 
chuck and svsoulmates 
ki4sry 
fulltime cruiser - on the hook in cambridge,md


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## chuck5499 (Aug 31, 2003)

SoulMates is a Jeanneau DS40 and has a Yanmar JH4 engine - maybe the issue is not yanmar but the engine access the boat mfg gives you - Jeanneau gives great access (at least i have it) and changing the impeller can be done without a lot of trouble - 
i would suggest that you do it at the dock before thinking you can do it at sea - it took me a while to figure it out at the dock but now i know i can do it at sea - may not be easy but i will have the confidence that i can do it - I did use a wire tie to get it in place and once i figured that out it was a breeze - 
just my thoughts 
chuck and svsoulmates 
ki4sry 
fulltime cruiser - on the hook in cambridge,md


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## Freesail99 (Feb 13, 2006)

> With the impellor I have avoided changing mine on my Yanmar 4jh because it seems so inaccessible


If possible, try and duck tape the bottom end of a cut up plastic bottle or container to catch anything, that might fall.


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## Freesail99 (Feb 13, 2006)

> With the impellor I have avoided changing mine on my Yanmar 4jh because it seems so inaccessible


If possible, try and duck tape the bottom end of a cut up plastic bottle or container to catch anything, that might fall.


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## Maine Sail (Jan 6, 2003)

Pamlicotraveler said:


> Halekai,
> 
> Your illustrated guides are very helpful. Really good. (did you do the stuffing box illustration a while back? You must have. I have saved it and used it)
> 
> ...


Yep that's why I said access is usually the biggest obstacle and to buy some spare screws...

Also if you change it yearly you should almost never have to change it in a sea.. Yannies are tough, but doable, and if you let it get to the point of no return it will take far longer than a changing the impeler to find those impeller pieces..

Remember the one in my article that was cracked was replaced in April and only run with limited flow, never totally dry, and it was still cracked in under 20 hours of use due to heat from limited water flow that still kept the engine cool enough.. Just something to think about..

*Cracked Due To Limited Flow

*


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## Freesail99 (Feb 13, 2006)

> With the impellor I have avoided changing mine on my Yanmar 4jh because it seems so inaccessible


If possible, try and duck tape the bottom end of a cut up plastic bottle or container to catch anything, that might fall.


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## SEMIJim (Jun 9, 2007)

Hal,

Thanks for another *excellent* "How To"!

I am quite surprised that little amount of flow restriction did that to your impeller. Not-to=mention kind of concerned. Perhaps it was a defective one?

Pamlicotraveler,

Suggest you stop avoiding it. If the impeller shatters you may find yourself facing the much more difficult job of trying to find all the pieces jammed-up in the various and sundry small passages in your engine block.

Only reason I haven't done mine yet is I'm still working out whether I want to: Just replace the impeller, also upgrade to the new back plate that has an o-ring and captured thumb screws, or upgrade to a whole new pump that does away with the grease cup and snap-ring. PO is "pretty sure" he did the impeller last season, and she hasn't had a lot of hours on her--esp. _this_ season, so I don't feel rushed. But it will have to be done, and it'll most likely get done yet this season.

Jim


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## HerbDB (Sep 30, 2000)

My Yanmar 3GM30F also had the pump cover plate on the side facing the engine block. I just loosen the belt and remove the pump with its mounting bracket as one piece. You can then change the impeller and gasket on the table or galley counter. I cannot imagine trying to do it without pulling the pump.

This is very easy to do, with the hardest part being getting the belt tension set properly. I use Bostik Never Seez on the mounting bolts to make sure I can break them loose easily with a ratchet.


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## BELLATRIX1965 (Jan 2, 2007)

*Add a light schmear of anti-sieze!*

One small addition:

A light coating of anti-sieze on the pump housing where the gasket lands (just on the housing gasket surface, NOT the impeller) will ensure that the whole gasket comes off with the cover. (an old trick often used in the Merchant Marine - it works!). Happy Sailing!


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## Maine Sail (Jan 6, 2003)

BELLATRIX1965 said:


> One small addition:
> 
> A light coating of anti-sieze on the pump housing where the gasket lands (just on the housing gasket surface, NOT the impeller) will ensure that the whole gasket comes off with the cover. (an old trick often used in the Merchant Marine - it works!). Happy Sailing!


Never tried that but a cool idea!!

I have tried TefGel but unfortunately it prevented the paper gasket from fully swelling and making a watertight seal..


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## sailingdog (Mar 19, 2006)

Halekai-

IIRC, Graphite is more likely to cause galvanic issues than copper or aluminum-based anti-sieze compounds, since it is higher on the galvanic scale than most metals. I seem to remember reading about a problem on CF boats where metal hardware was in contact with CF.


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## Maine Sail (Jan 6, 2003)

sailingdog said:


> Halekai-
> 
> IIRC, Graphite is more likely to cause galvanic issues than copper or aluminum-based anti-sieze compounds, since it is higher on the galvanic scale than most metals. I seem to remember reading about a problem on CF boats where metal hardware was in contact with CF.


After looking at the galvanic scale again I noticed that silicon bronze is #70 and resides next to most of the passivated stainlesses. Graphite as you know is the most noble element at roughly the #92 spot and copper comes in at #55 less noble than my bronze water pump. The idea is to keep metals as closely grouped together as possible so copper is actually closer to silicon bronze than graphite. I do worry about verdigris and the destruction of the copper behind the gasket though. FWIW I have never had a problem removing gasket material with Scotch-Brite and it takes all of about 30 seconds..

Using an aluminum based never seize puts you very far apart on the galvanic scale (#70 vs. teens) and would be, for me, a last resort.

I've had issues with copper never-seize when used in conjunction with stainless and a mild steel shaft coupling that's why I thought about using graphite. Instead of "never seizing it" it set up a galvanic nightmare and made the shaft & coupling actually harder to get apart. I switched to Tefgel for this and have never again had an issue with getting a shaft and coupling apart for service..


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## sander06 (Sep 18, 2003)

Great info as usual!!! I've found that doing any kind of work over the bilge will mean that stuff will instantly drop into it. Magnets are useless on stainless steel fittings, of course. I dropped a wrench one time standing at least six feet from the exposed bilge and the damn thing managed to bounce across the cabin and end up in the bilge! Now, whenever I can't find a tool or lost sock, I just look in the bilge. It's probably going to be there! Enuff bilge-rant!!!


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## LittleWingCA (Jul 17, 2008)

On my Yanmar 2QM15 engine, you have to pull the entire water pump assembly off to get to the cover of the impeller. This also means loosening the drive belt. When I had the engine survey done, the seasoned mechanic told me to buy an extra water pump assembly and a few rebuild kits. His thinking was that it was easier and quicker to just replace the entire pump assembly if the impeller failed, especially if you were underway, needed the engine, and were not in calm sea conditions. He told me to try and imagine having to rebuild the pump in 10 to 15 foot seas when the engine might be needed, and boat handling might require you to be available elsewhere. He said that to pull the broken pump assembly and install the new one could be done in under 10 minutes, but sitting at the table, rebuilding one, would take much longer, especially in rough weather and under stress, especially if the engine was really needed at that time. He suggested rebuilding the broken one later, when time, sea conditions, etc. were more favorable. Something worth considering, since you can't always predict when the impeller will go bad, and chances are it is when you really want to have the engine working.


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## Maine Sail (Jan 6, 2003)

LittleWingCA said:


> Something worth considering, since you can't always predict when the impeller will go bad, and chances are it is when you really want to have the engine working.


As I stated in my article if you replace your impeller annually, and don't run it with limited flow or dry, you should almost never have an impeller failure.

I have been replacing impellers annually and this is the first cracked blade I've had in 12 years and it was because I let it run knowingly with limited flow.

In twelve years of annual impeller replacements not once have I needed to change an impeller at sea or mid season due to failure. This is the first one and I killed it knowingly..

I would have never needed to replace this one if I didn't have a baby with a sleep schedule on board (actually, it's our sleep schedule and if she gets off hers I don't get any) and I had stopped for 5 minutes to clean the sea strainer.

Spare pump is a good idea. I carry one, yet to use it, and a re-build kit..


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## tdw (Oct 2, 2006)

I saw recently something referred to as a quick change impellor cover. Didn't take a lot of interest in it as our Bukh is a easy as can be to change. Yanmars can be a bugger so I wondered if these things were of any use. 

As per usual thanks to H for original post. I'm a believer in his principle of change once a year whether needed or not. After the first and only time I had an impeller fail and I didn't have a spare I've changed religiously every year and only bother I've had was from a bloody plastic bag. 

Also do the same with belts. It's not a huge expense and the peace of mind makes it all worthwhile. (and you end up with lots of spare belts and impellers, lots and lots.)


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## camaraderie (May 22, 2002)

Fuzzy...I think you are referring to speedseal.com


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## crzhors (Jun 11, 2006)

Greetings,well this JH4 has had a cooling prob since it's refit in Cartegena,lucky me,4th mechanic to get involved, figure out why no flow out the Exhaust.
short version,replumbed bad strainer routing,all the way back to the pump and disected pump to find the Backing plate missing! Probably in the deep bilge with 
many other parts,tools and sunglasses. this isn't a common replacement part.
Got it shipped in and now it flows like mad and runs very cool.too bad it smokes blue,overheated too many times... Lesson, Assume nothing! Cheers


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## SEMIJim (Jun 9, 2007)

halekai36 said:


> As I stated in my article if you replace your impeller annually, and don't run it with limited flow or dry, you should almost never have an impeller failure.
> 
> I have been replacing impellers annually and this is the first cracked blade I've had in 12 years and it was because I let it run knowingly with limited flow.


I still find this disturbing, Hal. I can't find your comments on the incident atm, but, IIRC, you let it run with mildly restricted flow for a short while. ISTM an impeller designed for this application should be able to tolerate that. What brand was the failing impeller?

I know you have had poor results with Globe's blue "run-dry" impellers, and I _have_ found others who have experienced similar failures: Where the hub breaks free of the surrounding material, so the vanes no longer turn. But I notice that some Globe impellers appear to have non-metalic hubs and some metal. One of the failed ones about which I read was reported to have a "plastic" hub. I wonder which yours was and, if it was non-metalic, if the Globe impellers with metal hubs are better?

Did you try to contact Globe about this early failure? I certainly would have. Tho I note that, in a couple of the articles I found, it was reported Globe was unresponsive to complaints about this product. I find that disquieting.

Jim


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## timebandit (Sep 18, 2002)

Just to add a few more tips.

Don't be a silicone junkie. If you clean off the old gasket as recommended you shouldn't need a sealer.

An old product called "Gasket Cinch" will keep the gasket attached to the cover while you are trying to get it on. Gasket cinch is aplied like contact cement, coat the cover(always attach the gasket to the removable part) and the side of the gasket that attaches to it and allow to dry and then using a couple of screws to aling the gasket just press. Gasket cinch is a low stick kinna stuff and will allow the gasket to be removed later with little effort.

Now you have the plate with the gasket attached just reach for your tub of BTG (Boat Trailer Grease). Go ahead, get a little on your finger and rub on the side of the gasket that goes to the housing.

BEWARE of rubbing grease on the housing as it might have a sharp edge.

As most mechanics know--If you put the first bolt in at the 12 o'clock position the cover will almost swing into place. Remember to always start all bolts before tightening any and then in a criscross pattern.

The next time you have to change the impeller the gasket will come off with the cover and be easy to remove and clean up will be a snap.

If that day comes when you have to change the thing in a hurry just pull the cover change the impeller and use the old gasket and you should be done in about 5 min.

If of course you have one that is easy to get to  

Rick


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## Maine Sail (Jan 6, 2003)

SEMIJim said:


> I still find this disturbing, Hal. I can't find your comments on the incident atm, but, IIRC, you let it run with mildly restricted flow for a short while. ISTM an impeller designed for this application should be able to tolerate that. What brand was the failing impeller?
> 
> I know you have had poor results with Globe's blue "run-dry" impellers, and I _have_ found others who have experienced similar failures: Where the hub breaks free of the surrounding material, so the vanes no longer turn. But I notice that some Globe impellers appear to have non-metalic hubs and some metal. One of the failed ones about which I read was reported to have a "plastic" hub. I wonder which yours was and, if it was non-metalic, if the Globe impellers with metal hubs are better?
> 
> ...


I got nowhere with Globe and if I remember correctly it was a metal hub.

My current thinking is that my Johnson impeller was an old one when I installed it. My baot came with two new spares but who knows how "old" they were. Johnson has since changed the rubber compound to a product called MC97 which is supposed to be better.

Limited flow can be enough to heat up the impeller but still enough to not over heat for a while. I have actually measured my raw water pump before (not on this boat) with my infrared under a "partial flow" and it was over 200 degrees..

The only lubrication is water and you have rubber on bronze spinning at a high rate of speed. Lose flow and you have less lubrication and cooling.

I've had this happen before and never seen cracks so my only guess is that the impeller was many years old and the rubber was aging before I actually installed it? That is my best guess because my engine had only climbed to about 190 and I was still getting a "mist" out my exhaust. If you've experienced a partial blockage you'll know what I mean by mist..

After this incident I bought 3 new impellers all with the new MC97 compound and threw away my one year old used ones. At $16.00 for an impeller why risk it..


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## SEMIJim (Jun 9, 2007)

halekai36 said:


> I got nowhere with Globe...


Yours would be the third incident I've read of where somebody had premature failure of a Globe RunDry [tm] impeller and got no satisfaction from Globe Composite Solutions, Ltd. That's enough for me. Any company can have product failures, but I expect vendors and manufacturers to stand by their products.



halekai36 said:


> ...and if I remember correctly it was a metal hub.


So much for _that_ theory 



halekai36 said:


> My current thinking is that my Johnson impeller was an old one when I installed it. My baot came with two new spares but who knows how "old" they were.
> ...
> I've had this happen before and never seen cracks so my only guess is that the impeller was many years old and the rubber was aging before I actually installed it?


That would certainly explain it!



halekai36 said:


> After this incident I bought 3 new impellers all with the new MC97 compound and threw away my one year old used ones. At $16.00 for an impeller why risk it..


Indeed! I'll buy two and install one this season. Next season I'll install the other and order a new spare. Each season: Wash, rinse, repeat.

How can you tell if Johnson impellers are fabricated with their new MC97 compound?

Jim


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## Maine Sail (Jan 6, 2003)

SEMIJim said:


> How can you tell if Johnson impellers are fabricated with their new MC97 compound?
> 
> Jim


Like this..


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## tdw (Oct 2, 2006)

camaraderie said:


> Fuzzy...I think you are referring to speedseal.com


That's the thing. Looks to me as if the only change is using gnurled knob instead of slotted screws. Not a bad idea I must admit but hardly revolutionary.

Any thoughts ?


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## sailingdog (Mar 19, 2006)

TDW-

The speedseal has slots for some of the screws IIRC, so you don't have to remove all the screws all the way to remove the seal plate.


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## Maine Sail (Jan 6, 2003)

*Re: Speed Seal*

Having had one on a boat that I owned, came with it, I can't understand why someone would pay good money for this.

It takes me all of about 30 seconds to remove all the screws and it took me the same amount of time to un-thread all the Speed Seal screws as they are the same thread pitch. I really did not realize much if any time savings with the Speed Seal..


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## SEMIJim (Jun 9, 2007)

Moyer Marine makes a replacement back plate for most Oberdorfer pumps on A4s that employs an o-ring and four captured knurled-head screws. The advantages are three-fold: No more having to replace the gasket, no more having to get a screw-driver on to the screws--possibly from an awkward angle/position, and no more dropping screws, etc. into the bilge .

Perhaps the Speed Seal cover offers some of the same advantages?

Thanks for the picture of the new impeller, Hal!

Jim


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## captbillc (Jul 31, 2008)

*ancient mariner*

haleki 36 that is a great w/p impeller photo ! i thought every one can use an aid to install the impeller. use a hose clamp and curve all the blades in the same direction as you tighten the clamp till they are small enough to enter the houslng. just be sure they are bent in the right direction when you push the impeller in. this makes the job easy. i am a retired diesel mechanic and use this method


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## SEMIJim (Jun 9, 2007)

Well, looks like I won't be obtaining a Johnson MC97 impeller for our engines Oberdorfer 202M-series pump. Johnson doesn't make one for that pump. Nor does Jabsco. The only impeller manufacturers that make impellers for our pump is Oberdorfer (Neoprene), Globe (out of the question), Barco (whomever _that_ is--same p/n as Globe, so I suspect that's a re-badged Globe) and Sherwood (which I cannot confirm because their web site is basically utterly and completely worthless.)

So it looks like it's the Oberforfer impeller for us.

Jim


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## ferg (Sep 27, 2009)

yanmar 4jh dte with litte acces - how to?


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## benesailor (Dec 27, 2012)

I do all the same except use this brake lube for assembly. Works with rubber as well.

http://www.autozone.com/autozone/accessories/AGS-Sil-Glyde-brake-lubricant/_/N-268d?itemIdentifier=752442&_requestid=8039288

I use it for my turn buckles as well.


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## sailinggreg (May 7, 2014)

This thread is a bit old but I'm hoping halekai36 or someone else can help - specifically with changing my impeller.

Fyi, I'm a new Ericson 30+ owner doing my maintenance for the first time. With a boat buddy, I managed to change my oil and oil filter, transmission fluid, both fuel filters and bled the system. All seems good!  I decided to wait on changing on the coolant until I figure a couple things out.

HERE'S MY BIG QUESTION:
I'm trying to change the impeller on my raw water pump. I have an Oberdorfer (p/n # N202M-07) raw water pump. Per the engines owner's manual, I removed the screws, front plate and the retaining ring. Using a wooden dowel to keep the shaft from coming out I was able to pull out the impeller (that took quite a lot of work). I took the impeller to the chandlery and got a new one. Pushed the new one onto the shaft and it seemed to go all the way on but there's just not enough clearance to get the retaining ring back into its little groove. Any ideas?

Yes, we compared the new impeller to the old one. It sure seems like its definitely the right replacement part (and went to a good chandlery that should definitely know). It seems like the new rubber is slightly firmer as would be expected, which makes it stick out maybe less than a millimeter more - just enough that we can't get the retaining ring back on.

Would really appreciate any help!


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## eherlihy (Jan 2, 2007)

Look at your "oil change" thread... I believe that I gave you the answer there.


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## Yorksailor (Oct 11, 2009)

ferg said:


> yanmar 4jh dte with litte acces - how to?


I have the same engine...I find it easier to remove the whole pump and replace the impeller working on the worktop in the galley...

My wife loves me doing it that way! But it only takes 20 minutes!

Phil


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## CS Cruiser (Dec 5, 2011)

When I store it away in a ziplock bag, whets the proper type of grease / lube safe for the impeller?


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## Maine Sail (Jan 6, 2003)

CS Cruiser said:


> When I store it away in a ziplock bag, whets the proper type of grease / lube safe for the impeller?


No grease but if you feel the need some 303 Aerospace Protectant is not a bad idea. Grease should not be used to lube impellers unless it is silicone based. The preferred lube for impellers is glycerin, about $2.00 at the drug store.


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## bvander66 (Sep 30, 2007)

tdw said:


> That's the thing. Looks to me as if the only change is using gnurled knob instead of slotted screws. Not a bad idea I must admit but hardly revolutionary.
> 
> Any thoughts ?


Went with speed seal, great piece of kit.
more than just knurled screws, the plate has a spinning teflon disc which prolongs impeller life and allows quick inspection without worrying about gasket issues.

Having had to replace impellers underway, much easier than using a blade screwdriver on screws while rolling around in a seaway.


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