Running with *NO* Impellar?

[jsz]

Just a thought here for those of us that use a pro-flushional or a fake-a-lake... If the water coming from the hose under pressure simulates water at the lake rushing in the intake hole, couldn't we run the motor at idle with no impellar??? After all a spinning impellar doesn't produce water, it only moves it, exactly what pressurized water from a hose would do.

This thought came to mind after changing my impellar every year with minimal hours of use and hearing many others with the same issue. Everyone knows the most damage occurs to the impellar while sitting for months in the winter. I wonder how long one would last if it never sat for more than a week (year round weekly use). Or using it in the summer and then removing it until the next season. I've heard of greasing it but that wont help one side from being compressed for months. I run mine once a month to keep everything moving but I've still found cracks in it at the beggining of the next season.

The purpose of this is not to find a way to save $35. I'm just currious and think it should work. Any thoughts?

[R&T Babich]

J Everyone knows the most damage occurs to the impellar while sitting for months in the winter. I wonder how long one would last if it never sat for more than a week (year round weekly use). Or using it in the summer and then removing it until the next season.

We bought our 2000 21V in 2006 and I believe it still had the original impellar in it. Two of the vanes had cracks at the base and the rest of the impellar looked brand new. The boat had 41 hrs. on it and sat for 2 years before we got it. Removing the impellar would certainly save the 2 vanes that are normally bent over from the stress. Regularly bumping the starter thus turning the pump would spread the stress around. The engine will usually stop in one of 8 positions. With a hose connected you probably wouldn't need the impellar at all to idle. If it were easier to remove it might be worth it to remove it for the winter. I'll probably just replace it every other year, just because.

How much water flow does the engine need to idle? I was wondering if the the raw water pump froze what could you do. By adding a tee/hose/valve from a washdown pump to the engine cooling pump return port I think it might supply an engine with enough water flow to run at idle. Install a shorter serpentine belt bypassing the raw water pump and you could at least limp back to the dock at idle.

[Graham Morris]

Impeller

If you have gone to trouble of pulling out impeller. Save any hassle and put a new one in and keep old as back up. Dont risk ruining a weekend skiiing for a few dollars

Graham

[chpthril]

This may not answer all your questions, but my best advise is to replace the impeller at the beginning of the season when you "Summerize" the boat. This way the new impeller will not sit all winter with the blades bent over in the installed position.

Some guys even remove the impeller when they winterize, and store it for use the next season.

[Jason B]

How difficult is changing the impeller? Easy, moderate, tough??
I read the how to thread and it seems easy, but it always SEEMS easy until you do it.

[chpthril]

How difficult is changing the impeller? Easy, moderate, tough??
I read the how to thread and it seems easy, but it always SEEMS easy until you do it.

I would say moderate for the avg. person with some mechanical skills and basic hand tools. What makes it hard, is reaching it (on a V drive)

[mtnsmith]

I just did mine, and reaching the impeller on a v-drive on a Marine Power engine was very difficult. I have so many scratches on my one arm it looks like I'm a junky. The write up was nicely done, but applies to a mercruiser powerplant. My impeller was 200 hours old and looked new except where I beat it up getting it out. I agree in warmer climates and when the boat is used year round, it will probably last quite a while. I plan on buying one to keep handy if we go on a trip, but I don't think I will do it for atleast 200 more hours.

[zad0030]

Yes technically you could launch you boat w/o the impeller and run it at idle but whats the point, you cant drive very far because it will eventually need to pump some water.

How difficult is changing the impeller? Easy, moderate, tough??
I read the how to thread and it seems easy, but it always SEEMS easy until you do it.

Depends on the engine you have, And if its a V or DD.

[Armstrong6]

The impeller is there to suck water through the system to cool the engine. The fake a lake does not so much provide positive pressure. But rather creates a water tight seal that will not allow air into your engine. The air makes the impeller cavitate and it will not suck through the rest of the engine. Without the impeller in the lake you WILL overheat your engine guaranteed.

[Coach]

I removed my impellar without any problems. I needed a paint can opener you get from home depot to make the process easier and I had a ton of room to get to mine in the RZ2. I don't have ballast tanks which would make it harder. I have a feeling getting a new one in will be a pain in arse.

[jsz]

I think a couple of you guys may have misunderstood the original question. I am not talking about "launching" or "driving" the boat. Simply throwing a thought out there and seeing if you guys think a motor can be cooled solely by pressurized hose water without an impellar. I would hope that we are all smart enough to have the impellar in before launching.

[whitlock87]

JSZ
I also live in CA. What I have been doing is every winter I run antifreeze thought the engine. I use Preston that has an additive to rejuvenate rubber and has a corrosion inhibitor. In the spring I flush out the antifreeze, and check the impeller for cracks and signs of ware. After 3 years I changed the impeller due to age not ware. I now keep the original as a back up.

[zad0030]

I think a couple of you guys may have misunderstood the original question. I am not talking about "launching" or "driving" the boat. Simply throwing a thought out there and seeing if you guys think a motor can be cooled solely by pressurized hose water without an impellar. I would hope that we are all smart enough to have the impellar in before launching.

Pressurized from like a power washer maybe?

[whitlock87]

Pressurized from like a power washer maybe?

OK back to topic.
Where I live the city pressure is 95psi. At 100 gpm that is more then enough to keep the engine cool.
A pressure washer might have high pressure (over 1,000psi) but has very little GPM. Around only 20. gpm is more important then PSI when it comes to cooling the engine.

If you can hook the hose to a T fitting inline with the water pick up, and have a valve to close the inlet, so you do not lose any flow, you will be fine. As you are forcing the water into the engine faster then if then the raw water pump could at those RPM’s.

[jsz]

Yes technically you could launch you boat w/o the impeller and run it at idle .

WHAT!!! Please tell me how ANY water will make it through with no impellar or pressure from a hose.

Pressurized from like a power washer maybe?

So here you mean 1800 - 2400 psi that most pressure washers put out? Not to mention the lack of GPM that Whitlock stated.
I'm sorry to say but I'm starting to doubt your mechanical expertise. Oops, sorry... just noticed you're 15.