Impeller destroyed in 75 hours

[josemolino]

G21 2014 with 409 engine. Today the temp raised to 100 and switched off. Restarted after cooling down and raised again so stopped and checked cooling circuit.
Intake filter clean. Heat exchanger clean. Antocooling just a bit low but nothing worrying? Thermostat looks ok although no water came out when I removed it.
Finally removed the impeller and it was destroyed.
I changed it in May and I' ve done less than 100h since then.
My worry and question are....
1. Why?
2. Do you think the impeller destroy is the cause or the consequence of something else?


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[Lakejackson]

What do you mean by destroyed? I just replaced mine (same engine) after about 100 hours and it was significantly worn. I was surprised at the amount of wear. My temps never got high though.


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[josemolino]

All the blades were broken. In previous years the impeller was almost new and just changed it for safety.

[Quinner]

Did you use a genuine PCM impeller?? Heard Sierra brand (iirc) impellers are junk. An OEM impeller should last for hundreds of hours if you don't run it dry. If you are running in weedy or silty water be sure your strainer is clean and all hose fittings are tight.

[josemolino]

Genuine. I checked strainer...

[lucky7t]

Replace my impeller every year . Are you in an area with sand ?

[josemolino]

Replace my impeller every year . Are you in an area with sand ?

No, water is quite clean excepting debris in winter but I checked strainer and was ok. The boat is from 2014 and had no problems until now. My previous nautique from 2007-2014 never gave me this problem

[Quinner]

If you are not running it dry on the trailer or boat lift then perhaps you have an air leak somewhere. Make sure the strainer is clean and the gasket is still there, also tighten all the hose clamps on the intake side of the impeller back to the pickup, use a nut driver not a screwdriver. If your trans cooler is on the intake side you may want to pull the hoses and inspect for any debris there, be careful as those ends as they can be a little fragile.

[josemolino]

If you are not running it dry on the trailer or boat lift then perhaps you have an air leak somewhere. Make sure the strainer is clean and the gasket is still there, also tighten all the hose clamps on the intake side of the impeller back to the pickup, use a nut driver not a screwdriver. If your trans cooler is on the intake side you may want to pull the hoses and inspect for any debris there, be careful as those ends as they can be a little fragile.

Thank you, after your post it is clear to me that it worked dry, so the problem is in the intake side... that is less worrying...

[xrichard]

A buddy and I both have 2015 G boats with the 409. Both of us had seriously worn impellers when changed at around the 100 hour mark (typically annually or close to it). I've been changing impellers at +/- 100 hours for 20 years and they've always looked near-new. Good enough that I hang on to them as spares.

I watch the temp gauge regularly, so I don't think it's a leak on the intake side (...in my experience, even a tiny leak at the strainer or elsewhere before the pump can cause significant problems). I haven't checked the strainer since I changed the impeller as I haven't finished the service on the boat--I'll do that before I take it out next. I'm not running in dirty water...at least not any dirtier than my previous boats that haven't had a problem. I never run dry on the trailer.

I've haven't worried too much about my impeller in part because I use the boat year round so it never sits for months at a time. But now I'm hearing more stories of trashed impellers in these motors and it has me concerned. Moving forward, I'll change mine with every oil change at 50 hours (which is what PCM recommends as the service interval...though it's not clear to me if it's inspect and replace as necessary or simply replace. I'll opt to simply replace).

FWIW, I've changed nothing operationally...same water, same use, same maintenance. It makes me wonder if there's an issue with the current design of the raw water pump or if the fact that my the 409 is closed cooling somehow increases wear on the impeller (...though I can't imagine how). Or, perhaps, the impeller itself has changed and it simply is not as good as it used to be.

[nyryan2001]

150hrs (2 winterizations) on my first impellor.... Slight damages to the tips of the fins.

im about to change mine again here in a couple weeks

[shag]

I have noticed in years past, that the closed cooling boats seem to run a little hotter... I wonder if that has anything to do with it...

[nyryan2001]

I donno? These run 150-160 while moving.... 165-175 at idle?

[lucky7t]

I remember an older post about some bad impellers . I thought Jeff commented on it. Might want to research that .

[Paxdad]

I experienced a white box defective impeller from NautiqueParts in fact two of them!! Unless the impeller is from a PCM package I don't use them.


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