Impeller Options

I put a new impeller in about 40 boat hours ago and need to put another one in. This is just irritating at this point as there is no serious damage, but are there more durable options? I have been using the standard Mercruiser / Quiksilver brand. Seems like this part fails more than it should.

Oh I have never started it out of water.

Look into a Globe impeller. Supposedly they can withstand up to 15 minutes running dry..... guess that makes them more durable. I'm on my first one this year. So far I have about 50 hrs on it & no problems.
Also look into what might be causing yours to go so fast. Any chance your boat is sucking debris to cause it?

never never start or even turn over the engine w/o a fake-a-lake or boat in the water. that you probably knew but must be repeated for those who may read this.

Sorry for the hijack:

Hey Mike, I have always started my boats dry as a part of the winterizing process to blow the mufflers out. Especially when you ride late or early in the year & have to winterize several times. This has never been a problem.

/hijack off

never had to winterize anything due to where I live in california so I can't speak as if I know exactly what it includes. I would assume there would be some anti-freeze liquid in the impeller housing acting as a one time lube for the impeller for a few seconds. all I was trying to get at was the friction from dry starts will tear impellers up. theres nothing more then rubber rubbing on metal in the housing when no water is present. lots of heat/bad news for your rubber impeller.
mike

Maybe some clarification should be made then. Starting your boat's engine when it's completely dry is a bad thing for the reason you listed.

But if you have any water in your engine (like when you just pulled it out of the lake & it's sitting in your driveway), you can bump start your engine for a few seconds without any damage & it will blow water out of the engine & exhaust. This is part of winterizing your boat.

I've done this for years, even with the old Johnson impellers. Any water sitting in your mufflers can freeze & crack your mufflers. Or you can blow them out & be all good.

This is the impeller I was referring to earlier.

Globe Marine Run Dry Blue Impellers

(Message edited by bill_airjunky on July 28, 2008)

Atthetlake,

What year is your and how many hours are on it?

Sounds like a worn out impeller housing is the root cause of the short impeller life. What does the inside of the housing look like? Does it have a blue-ish color and/or scared up? If so, replace the whole housing.

The boat is an '04 with aprox 150 hours. I replaced the housing in my last boat at about the 5 year / 500 hour mark, but would hope this one isn't trashed already.

Those Dry blue impellers are going in next time around, but will have to put the stock replacement in now as I need to use the boat ASAP.

Yeah I never run it dry and the lake we ride is pretty clear of floating debris, but of course you never know if you did suck something in. Will def. check the intake. Thanks for tips.

When I changed my impeller last time I used high heat faucet grease. I coat the inside of the impeller housing. That way the rubber doesnt stick to the housing and create heat instantly when first started and possibly dry...This impeller seems to be holding up pretty well. I have also noticed that a good indicator of the impeller going out is when I start to see bubbles going throught the clear tubing coming off the exhaust manifold and going down to the shaft seal. So long as the line stays full it seems like my cooling system is working fine..see bubbles and its time to check/replace the impeller.

just to fuel the fire on this little discussion: wouldn't the water in the water pump and housing then be transferred to your exhaust mufflers?

Yea, Nacho. But your talking seconds for that to take place.
The next time you pull your boat out of the lake, start it sitting on the trailer at the ramp. Watch how long it takes till there is no more water coming out of the exhaust....... maybe 1 or 2 seconds, tops.

I've put over 1500 hours on 3 different boats since 2001. I only changed impellers on 2 of the boats after 2 years and 300+ hours each. I have never had an impeller to fail. I don't do it often but I do sometimes start the boat for 5-10 seconds without hooking up water. I think there is definately something else wrong with your pump.

OK once and for all: do not run your boat engine without water going to the water intake ever ever ever never never never it is not good and is unnecessary. not for 1 second not for 5 seconds, just don't do it. an impeller must remain flexible when it gets heated up it causes the rubber to become brittle. carry a spare impeller and housing ($50)...you may need it out on the water and if you don't you will run into someone who needs it someday because when your impeller goes bad...your fun is over. ive saved people at the ramp with toasted impellers before ive seen alot of impellers fall to bits and clog the oil cooler. they are the weak link. an impeller can't take being run dry so don't push your luck. even the rundry impellers...the other components/housing is not made to run dry.

A pure synthetic brake grease is designed to not harm rubber and to lubricate metal and rubber parts. It often comes in fairly small tubes.
I have some I keep with my spare impellor.

I just replaced my impeller this weekend at Lake Oroville, and the guy at the boat store said to coat the housing and impeller with white lithium grease.

As mentioned above, always carry a spare impeller. I didn't and what took about a half an hour of labor became an overnight project trying to find a new impeller at 5pm on Saturday afternoon.

grease in your pump does nothing after 10 minutes its gone washed away by the water your pump is pumping...soap is the easiest thing to use to get the impeller inthe housing and it does not matter which way the vanes go...they self correct and it does not hurt them. grease in the pump is simply polluting the water.

So how do you winterize your boat, Andy?

Interesting thread and lots of interesting advice?

For the past 20 years I have always bumped the boat dry at the ramp every time before launch. I replace impellers ever second or third year, most used impellers look like new when I pull them out. I have had impellers fail when my strainer on the inlet side was not sealing well preventing the pump from priming. Another one fail from running after the fake-a-lake fell off.

Of course I always carry a spare in the boat, the tools and know how to make the change on the lake.

Replaced the impeller and it pretty much exploded with less than 40 hours. No obvious debris at intake and I used soap/water to put in the new one. The housing looked smooth so I still do not know why this one went so quick. Seeing how this one went so fast, I put water in the lines so it would have a little bit of liquid for the first few turns.

Oh well I think a blue one is going in next and I will order 2 to have a spare for the spare though I hope I do not need change it any time soon.

Mikeski,

I am interested to hear how you change the impeller with the boat still in the water. Once you remove the impeller housing how do you keep the water from rushing into the boat through the fresh water intake hose that connects to the back of the impeller housing. We wanted to try to change the impeller while on the lake, but we had no way to plug the hose and prevent the boat from taking on water.

Thanks.

Robert, newer boats, built 2005 or later I believe, are required to have a steel or brass (not plastic) cut-off valve attached to the through hull fitting. USCG regulation.

Also if the raw water pump is above the water level on the boat, and it is on most v-drives, water will not be pushed through the lines.

well to summerize I don't winterize...I am in California near the Delta. It just about never freezes here. my boat runs 12 months out the year. what the hell is winterizing? (JK) putting drysuits and a heater in the boat?

to change on the water...stuff a rag or something in the hose to stop the water from pouring in(or you may sink!)or have someone keep their hands on it.

if you are only getting 40 hours something is wrong...check out your housing for any cracks, i have had a cracked housing before.

Robert,
as long as your impeller is above the water line you should have no problem. I disconnected the line to my impeller while my boat was still in the water but as long as i kept the opening above the water line i was ok.

Andy loves delta glass (bftskir):
well to summerize I don't winterize...I am in California near the Delta. It just about never freezes here. my boat runs 12 months out the year. what the hell is winterizing? (JK)

Typical. The rest of us have to winterize or risk the water in our engines, heaters, exhaust manifolds & mufflers freezing & breaking those items. Most have a way to get the water drained, ie; petcocks, pull a hose, etc. But the mufflers dont. So we start the engine for a few seconds with the boat out of the water, which will clear all the water from the manifolds & mufflers, not to mention a lot from the engine.

After having done that for 15 yrs myself, and knowing dozens of others who do it, dealers who do it, etc. I'd be interested to hear how you can validate the statement, "do not run your boat engine without water going to the water intake ever ever ever never never never it is not good and is unnecessary"......... especially when you have never even winterized a boat yourself.

JK means just kidding
what you are doing is detrimental to the life of your impeller. if you must run it like that I guess you just change impellers more often. In the 28 years i've been boating ive seen alot of impellers fail. also numerous articles clearly state that running it dry will ruin an impeller in a minute. Do a search. It comes up.
http://www.sailmag.com/boatworks/bw08.impeller.pdf etc etc etc....can you say running it dry does no damage to it?

Interesting that the author of that article suggests the Globe run-dry impeller too..... because it can survive for up to 15 minutes without water (not that I'd suggest anyone run their engine dry for 15 minutes all at once).

Thanks Andy.

I never changed an impeller. How do you do it? Is it hard to do?

i tryied to search on other thread, and couldn't find any walktroughs or hints on that.
I have a mercruise black scorpion