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Change Impeller Every Year?


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Had mine done a few weeks as part of the 200hr major service, going to get done at the start of every season when I get the 'bu checked over.

Rather spend a few hundred at the start of the season and not have worry than spend nothing and eventually have a drama.

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I replaced one two years ago in the spring just because it had two full years on it. The new one only lasted a couple of months before the hub broke loose from the vanes and stopped working, obviously. I put the old one back in and it's still going strong....so essentially four years on it. Now, I have another new one in the boat ready to go, but I'm done replacing them "just because" and will inspect/replace as needed.

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Being a CM, easy access.

If I ain't using the boat for 8 weeks or more, I pull the impeller & put it I a bag tied to the steering wheel.

That way l can't miss it.

After about 3-4 weeks the vanes straighten out.

Bit of Vaseline on the vanes B4 storage seams to help keep it pliable & easier to re install.

Takes about 5 min to re install & bump the engine to adjust all the vanes the same direction & have been running the same impeller for 3 years or about 260 hours now.

I carry a spare just in case as well.

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Being a CM, easy access.

If I ain't using the boat for 8 weeks or more, I pull the impeller & put it I a bag tied to the steering wheel.

That way l can't miss it.

After about 3-4 weeks the vanes straighten out.

Bit of Vaseline on the vanes B4 storage seams to help keep it pliable & easier to re install.

Takes about 5 min to re install & bump the engine to adjust all the vanes the same direction & have been running the same impeller for 3 years or about 260 hours now.

I carry a spare just in case as well.

Pretty sure that the impellers say not to use petroleum jelly on them. Must not matter if you are getting away with it. Supposed yo use glycerin for install.

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The 1st inboard boat I bought was about 15 years old, with about 300 hours. It had the original impellor. Could tell because the factory paint was still on all the fasteners.

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Just my opinion, but replacing wearable parts before they are worn isn't cheap insurance, it's stupid. Would you replace your brake pads with half of their life left?

Brakes wear slowly over time, and you have some indications and warning before they are totally gone. Impellers don't do that.

I change mine every year - pull it in the fall and new in the spring as part of the de-winterizing process. I run about 50 hours a year on a clean lake.

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Pretty sure that the impellers say not to use petroleum jelly on them. Must not matter if you are getting away with it. Supposed yo use glycerin for install.

You're 100% right. Unfortunately the Indmar manual confuses the issue and says to "lubricate the impeller with Vaseline and seal in an airtight bag" while the Johnson manual explicitly says NOT to use it, as it will damage it.

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Most non catastrophic impeller failures will give you a warning if you're paying attention to the warning signs and your gauges are accurate. As the impeller experiences normal wear you will notice the boat temp climbing during idle and decreasing back to normal under higher speeds. This is due to the impeller's reduced efficiency and the thermostat's inability to compensate for the reduced water flow.

For those of you putting on excess of 75 hours in a season, I wouldn't be messing around for $35 and would just change the impeller. We boat primarily on a small inland lake and live in a northern climate. A real good year for us is 50 hours as we have no long cruises or drives to make. Throw the wheel on the Shorestation, push the boat off and throw a rope to start skiing. This year was particularly bad and most of us on the lake got less than 35 hours in and most of that came over this past month. Based on this I've decided to go to the new every other year program. I will however be paying close attention to the cooling system looking for obstructions in the trans cooler to ensure everything is as it should be.

As to multiple failures in a single season and the picture of the impeller melt down. Neither of those are normal under normal operating conditions and reasonable maintenance. If your having impellers going out every month or two it's time to fix the cause and not the symptom. I would expect you're not getting proper flow, or something other than water is flowing through the pump or the pump itself is at issue (hence the other comments on if you're beaching the boat). The 300 hour impeller failure is what you would expect to see from am impeller that has rotted and has been used well past it's service life. I've helped replace similar looking impellers while on the lake and getting all the pieces out is a real pain. Not doing so can lead to the cooling problem from hell as they cause obstructions throughout the system.

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You're 100% right. Unfortunately the Indmar manual confuses the issue and says to "lubricate the impeller with Vaseline and seal in an airtight bag" while the Johnson manual explicitly says NOT to use it, as it will damage it.

I usually just "lubricate" mine with a little liquid hand soap.

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Mine gets a new one every spring, i pull the old out in the fall after winterizing. I keep the old one in the boat then as a spare if it looks good. I figure its cheap insurance, plus on my old boat i had one go out, which resulted in head gaskets... I have been getting 120-150 hrs. a year though as well, and run a lot on a river that has a lot of sediment

Edited by Dale974
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I read that they can freeze and become brittle during winter. I replace every spring for that reason

Well, as a resident of MN where we actually have winter - I'm going to say that is false ;) Tens of thousands of boats sit through the winter here with their impellers in place.

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I read that they can freeze and become brittle during winter. I replace every spring for that reason

I've owned my current boat in eastern WA where we see below 0 temps every year. We ride year round, including the Air Santa run in brand new boats. So these boats get winterized multiple times every winter. I use the Globe, which is pre-lubed. Dealer uses either the OJ or Globe, depending on the owner's preference. I've never seen or heard of a frozen impeller.

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I read that they can freeze and become brittle during winter. I replace every spring for that reason

Yes that is possible but it would have to get to something like -20 at least probably more like -50 for that to happen.

Edited by robbennett
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Well, as a resident of MN where we actually have winter - I'm going to say that is false ;) Tens of thousands of boats sit through the winter here with their impellers in place.

Believe it or not we have real winter here too. I know it doesnt sound like it because its just NC but we do have the highest elevation in the east and have extreme temps in the winter. While our snow totals are just under 100" per year on a good year we still have negaitve temperatures often with winds that are horrible. Just because I read that they can freeze just makes me replace the impellars in the spring rather than at lay up because why risk it if there is just the slightest chance it could happen? If it never happened anywhre in the world before doesn't mean that it wouldn't happen with my crappy luck for the first time ever.

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An impeller costs $35. If that's the only cost for your peace of mind I say replace it anyway. You can always pull it and put it in a zip loc bag with lube on it and store it indoors. Then you still need a new gasket when you re-install in the spring.

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Believe it or not we have real winter here too. I know it doesnt sound like it because its just NC but we do have the highest elevation in the east and have extreme temps in the winter. While our snow totals are just under 100" per year on a good year we still have negaitve temperatures often with winds that are horrible. Just because I read that they can freeze just makes me replace the impellars in the spring rather than at lay up because why risk it if there is just the slightest chance it could happen? If it never happened anywhre in the world before doesn't mean that it wouldn't happen with my crappy luck for the first time ever.

Talk to me about winter when it is below zero for 2 months straight;). We call -20 temps January. ;). Never heard of it happening, but if it concerns you then keep doing as you do.

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My experience is there are several variables: impellers themselves have quite a range on quality, so not surprisingly some last several years & some do not. One needs to check the impeller housing carefully for surface finish, particularly if you are using the plastic replacement kits from Sierra as a rough or worn housing can quickly destroy an impeller. My gauge is to carefully watch the temps on the latter part of the season, carefully inspect the parts when disassembled for the winter storage season and use that as a guide on whether a new one or used one goes back in next spring. Of course, success then ends up being totally random at times.

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