water pump impeller

[kcoben]

how often do you guys pull or inspect the raw water pump impeller, each year or so many hours and what is the life.

[charlesml3]

Impeller gets replaced every spring, regardless of hours or how it looks. You can't really look at one and tell it's bad unless it's shredded. It's a $40 part and about an hour of labor to do. It's cheap insurance against an overheat.

-Charles

[GMLIII]

Impeller gets replaced every spring, regardless of hours or how it looks. You can't really look at one and tell it's bad unless it's shredded. It's a $40 part and about an hour of labor to do. It's cheap insurance against an overheat.

-Charles

Not that is is right or wrong but I''m replacing my with 150 hours and I bought the boat last year. After this season I will replace it again prior to next season

[scottb7]

I don't think replacing every year is necessarily bad advice. But frankly, I don't. I get "up close and personal" with my boat every fall and after winterizing, I remove the serpentine belt, the impeller, and the housing, and leave on my work bench all winter, while the boat is in storage.

So if it looks new I put it back in. But I live on a small lake and so there is no risk of getting stranded and the window of not having a neighbor to tow me in is very small in early spring and early fall. (When we are boarding and "own the lake")

I just figure with my luck I would take out a good used one and but in a new defective one...I believe a tried and true impeller is a good thing. But I am maybe the outlier. Plus honestly while they are rated for a small amount of hours, many boats go their whole existence for owners that don't bother, 100s of hours without a problem. So if you inspect and see little wear it I don't see why it has to be replaced.

[charlesml3]

OK, this is probably going to turn into yet another inane argument with Scott, but you cannot look at an impeller and tell if it's good or not (unless it's just shredded).

Here's the deal: The impeller runs inside of a pump casing that is not circular. It has one side that's kinda flattened. As the impeller vanes reach this point, they bend over, forming a very tight seal with this face. Once they pass this spot, they "stand up" again. Over time, the rubber vanes lose their elasticity or flexability. They have to just from bending back and forth so much. When this happens, the seal against the flat part on the pump isn't as good as it used to be.

This exhibits a very particular symptom. When you're running across the lake, the engine will cool just fine. When you slow down to idle, the engine temperature will start to climb. This is a good sign the impeller has lost some of its elasticity.

As I said above, there's no real way to visually inspect this and see if an impeller has lost elasticity. It'll look just fine, but still not draw enough water at idle to keep the engine cool. An impeller is a wear item. It's designed to be replaced regularly.

You do two kinds of maintenance on a boat: Preventive or Disaster Recovery. Pick one.

-Charles

[kcoben]

Scottb7, your words ring true,I replaced the impeller in my first boat after several years and hundreds of hours of use only to have it fail and scatter chunks of rubber through the engine, after that event my boat idled warmer then ever before, maybe the new part had been in stock longer then the replacement had been?

[Infinity]

I replace every year for same reason but it really comes down to how you use your boat (it wears out faster NOT being used cause of what Charles said....the vanes will stay bent and not spring back after a while). In my owners manual it says to check it every 50hrs and replace after 100hrs. Also depends on if you are careful to never run it dry AND how you winterize. If you pull it out over winter, its gonna do a lot better than leaving it in IMO. I also fill my system with AF so it stays wet, but that does not really matter to me since I replace mine in the Spring and not the fall so it does not sit in there compressed all winter. I heard of one guy who checked it frequently and it lasted 8 seasons, others are not so lucky. On new, guess its luck of the draw on if you get a defective one since that can happen too. I guess they type of water you boat in could possibly effect the life too, tho I dont know that to be a fact, just thinking brackish water may effect it differently.
Takes me 30mins to replace and i enjoy doing that stuff, so I replace it. I also coat it liberally with dawn dish soap when I install so its well lubricated for the 1st startup and I am very gently on boat the 1st run out while checking things over carefully, looking for leaks, watching temp and all that good stuff. I just replaced mine last week and the old one I pulled out looks brand new, but I still replaced. I do keep it as a spare tho in case its needed.

[scottb7]

Nope, I won't get into an argument...but the reader should be reminded that charles statement of "This exhibits a very particular symptom. When you're running across the lake, the engine will cool just fine. When you slow down to idle, the engine temperature will start to climb. This is a good sign the impeller has lost some of its elasticity."

is NOT NECESSARILY a sign of "lost...elasticity". Could be, but this also happens on a brand new one, cause of engine rpm and quantity of water decreasing. So very normal to increase engine temp a bit as you slow down or if you slow down pretty quickly.

But all i am saying is that i know that i am the guy that will get a defective one so if i got a good one i keep her going.

p.s. by monitoring the temp gauge i can manage lost elasticity of a good impeller. But as charles points out - quite accurately - tough to manage once in "disaster recovery" mode. So i pay more attention to temp on a new one then an old one just to be sure it is not defective and shreds early on...

[2001SAN]

I remove it every year and in the last couple of years I just put the old one back in. The blades return to normal form once out of the pump. I believe a certain veteran member on CCF has been running the same impeller this way for a couple of decades! I never run it dry and always lube it before putting it back in and prefill the water strainer before turning it over. That being said, I see no harm in changing it frequently either for piece of mind. I have never seen a shift in temp between running and idle but we run in pretty cool water
here in Ireland!

Carrying a spare is a must either way.

D.

[Dgee]

I put in a fresh one at the start of every year, just been a habit and hasn't let me down... I also keep a spare in my tool box in the boat. Nothing worse than being on vacation far away from somewhere to get parts and having an impeller shred.

[charlesml3]

Nothing worse than being on vacation far away from somewhere to get parts and having an impeller shred.

Luck favors the prepared.

[peteSki]

I put in a fresh one at the start of every year, just been a habit and hasn't let me down... I also keep a spare in my tool box in the boat. Nothing worse than being on vacation far away from somewhere to get parts and having an impeller shred.

Same for me. New one in spring and I keep the old one in the boat just in case along with the required tools. I usually do 100-150 hours per year.

[Tom_H]

I'm a spring replacement guy myself, but also have about 4 or 5 'spare' impellers in the tool box that look about perfect. The biggest thing is to buy OEM (Sherwood/PCM), as the off-brands always have more tendency to shred or slip on the hub.

[GMLIII]

Same for me. New one in spring and I keep the old one in the boat just in case along with the required tools. I usually do 100-150 hours per year.

peteSki I would agree with you in changing the impeller each spring but having tools and an extra impeller on your boat to change a failed impeller "on the fly out on a body of water" is this really realistic? I'm not being critical but I just don't see that I could actually change an impeller in a V-drive engine while I'm out in my boat during an impeller failure. I would think it would be dam (n) near impossible and I would just flag someone down to tow me to a marina or my dock. Please let me know what I'm missing here.

[Infinity]

Guess it depends on the boat. With my ZR409, as long as I had a 10mm and 15mm sockets, I could change mine in 20mins on water if I had too. 15mm to release tension on belt and remove....then 10mm (with extension) to remove the 3 screws on impeller housing, needle nose pliers may be required to remove impeller, tho with mine I have always been able to work it out by hand since I replace every Spring. Stick new impeller in there (when doing it at home, I always slather with dawn dish soap for easy and so when starting up its nice and slippery), tighten and reinstall belt and good to go....IF the impeller did not shred, if it did its risky that pieces are in system.

Just saying....it can be done if prepared, but personally I don't carry a spare impeller for day trips for same reason GMLIII mentioned. Just as easy to get tow to dock and I keep BOATUS towing and also have towing coverage on my SkiSafe policy so covered from 2 fronts tho I will likely drop BOATUS after this year since I added to SkiSafe (which covers me on water or while towing with truck for $1000). However if I tow boat out of town for weekend trip, then I do take tools and extra parts since I would not want to be hours away and lose vacation time over something I can fix easily. I do however always keep a spare belt and 15mm on boat cause easy to replace and something that could potentially happen.

Other engines could be harder, I have never worked on an H5 or H6. I heard they are easy, but do not have firsthand knowledge of how easy/hard it would be. Just know my engine like back of hand since I enjoy working on it, its therapeutic for me (forget cars tho...just love boats and motorcycles)