Is my impeller the cause of lake-a-lake not working ??

[snakekans]

Hi guys !

I'm new to the boat world and purchased last year a r20 2012 with the pcm 303.

I only used it once last year and it seemed to run well, so this year before I hit the lake i hook up a fake a lake and water isnt flowing (can see from the filter and no water in exhaust)

So I shut it down, remove the impeller and it seems it was never replaced, blades are folded. I believe I need to replace it, but is it in bad shape enough for the fake-a-lake to not work ?? or there could be something else I should check before hitting the lake ?

Please see attached picture.

Thanks !!!


impeller.jpg

[Bryan]

How long did you run it before you got worried about not seeing water and shut it down?

[snakekans]

About 15-20 seconds

[ChrisSnow]

Something to bear in mind is that if you are pointing down hill it takes a while to fill the exhaust enough to start overflowing. Whilst you're impeller probably needs replacing it's unlikely to be the problem if there even is one.

I personally stick a bit of 1-1/4 hose onto the pump inlet and shove the hose down that or into a bucket. Much easier to gauge flow and be sure of no air leaks. Plus it can't fall out of place!

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[IDBoating]

seems it was never replaced, blades are folded.

The blades will take a "set" and look something like that after a while, so that alone isn't much to worry about. But that impeller does look a bit aged. I'd replace it.

Preventing the impeller from taking a "set" is one of the reasons you are supposed to remove it during winter storage. Dry it thoroughly, then store in a sealed ziploc bag indoors to minimize exposure to extreme temperatures. Do not store near natural gas appliances (like a water heater), as the combustion byproducts can deteriorate rubber compounds (that's why I take the extra step to store mine in a ziploc, for added protection).

[chpthril]

If the block was drain empty for winter, as it should, it can take more than 20 seconds for it to fill and then start to dump out the exhaust. Are you sure you had the F-a-L on the correct thru-hull?

Thats not the worst looking impeller ive seem.

[snakekans]

Well water was not flowing trough the filter under the back seat about 3 feet after the f-a-l hull intake.

In fact I was downhill, next time I will try to be more level.

[chpthril]

Sounds like a possible air leak. Loose hose clamp, leaking o-ring on the raw water filter, wrong thru-hull (yes, I know, but ive seen it before)?

[Bryan]

I should pay more attention and probably know this.. But does the engine have to warm up enough for the thermostat to open before water will circulate completely and come out the exhaust?

[chpthril]

^^^^ No, the engine does not have to warm up to t-stat temp before water circulates to the exhaust. In most cases, the exhaust gets water first. However, if the complete engine is empty from winterizing, the block will fill first. Basically a case of path of least resistance. Everything needs to fill, before water is pushed out the exhaust.

[Tigenator]

On a side not, how often should you change the impeller?

[ChrisSnow]

Some swear by every year. Others are happy with every other.

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[IDBoating]

I always keep a spare impeller around, either new in the packaging or the last one I swapped out of the boat if it was in good condition. I replace impellers no less than every two seasons, but I inspect it every year when I remove it for winterizing. Some seem to wear differently than others; I've had lower-hour impellers look far worse than higher hour impellers for no obvious reason. They all see reasonably clean water... I have a prefilter, I'm only in a freshwater lake known for its clean water, etc.

[laserfish]

Had too many weekends cut short by not replacing the impeller every year. Have never had one go out the summer it was put in so I say cheap insurance. The only impeller that I had that did not last was a silicone run dry impeller. Lasted one trip and no, I did not run it dry. Genuine Mercruiser parts now.

[supervol0509]

That impeller looks ok to me. Just make sure none of the blades are cracked. I normally remove impeller, during the winter, and reuse the following season, if it looked alright. Would replace at least every other year, though. I had originally read that you should coat the stored impeller in petroleum jelly, but I guess the impeller manufacturers recommend a water-based lubricant. I can tell you the petroleum jelly coated impeller is way easier to slide back in there. You should see water out of the exhaust within 20 seconds. Make sure you are using a standard hose, not this little coiled hoses that have about half the diameter.