Regular maintenance - change just the impeller or entire housing too?

[Dukedog]

I wasn't really speaking on your suggestion. It's a good one. I was speaking more about not replacing a perfectly good one with possibly an lower quality aftermarket one.

 

[Texasmark]

I don't want to hijack this thread, just asking a supplemental question.
Do you guys put a little grease on the impeller fins when replacing it?
If so, any type grease? Vaseline work?

Soap on the impeller for inital installation. Helps the cover to slide on as you rotate the drive shaft while pressing the cover down. Most rubbers don't like petroleum based products especially those designed for water, not oil environments.

3 problems with impellers I have found are the blades taking a "set" whereby when the blade moves from the compression side of the eccentric chamber to the release side to start the compression cycle again, it doesn't straighten out and follow the chamber...it stays bent. Engines sitting up for a long time usually have this problem.

Other problem from an old impeller having sat up for a long time is blades getting brittle and breaking rather than bending and the pieces not only decrease water pressure, they also find themselves in undesirable places clogging up water ports or functioning valves in the cooling system.

Usage problems are the wear out the tips of the blades due to abrasion and running without water or running in shallow, sandy water, or brine where the water contains abrasives can do that.

Most of the guys who post on here run pressure monitors to monitor pressure as their maintenance trigger. I don't boat commercially nor make long trips out in big water but want to know my engine's temperature so I use a thermostat and dash temp gauge. To each his/her own.

 

[Texasmark]

The rest of that is that any time you touch something you stand the chance of "collateral damage". With that in mind, I don't change things just for the sake of change and changing an impeller is on that list since its a very seldom experience and on my current engine I haven't ever done it....but I do have a new impeller in my parts caddy. I use my tell tale as my "wear factor" gauge. If I get a good strong stream at idle I am good to go. To each his/her own.

 

[racerone]

Water pressure gauge is a good investment.-----A shop charges for labor / skilled service.-----There is no labor when an owner wrenches on a motor !!

 

[ahicks]

Just don't assume that because it's pissing everything is OK. Assuming it's not accidently run out of water, I think an impeller's age will take out way more than wear does. I tell people if they don't know when the impeller was replaced last, they're running on borrowed time. Pressure gauges are awesome, but not very common on the stuff I see....

 

[racerone]

I have seen many motors that overheated even with a pisser.-----The general public and the many " covid newbies " just do not know how motors work.-----Found this on 2 motors 70 HP with totally fried impellers .-----One of them at a recently sold summer home.-----I can only think that it was the real estate agent.---- Repeatedly showing that this1998 motor would start and run with no muffs hooked up!!

 

[ahicks]

I have seen many motors that overheated even with a pisser.-----The general public and the many " covid newbies " just do not know how motors work.-----Found this on 2 motors 70 HP with totally fried impellers .-----One of them at a recently sold summer home.-----I can only think that it was the real estate agent.---- Repeatedly showing that this1998 motor would start and run with no muffs hooked up!!

I gotta believe a LOT of people learn that lesson the hard way.

 

[racerone]

As a young technician I used to keep old impellers to honestly show the old folks why they need to install a new one.---To save them $$$$ big time.-----Not any more.----I just kind of chuckle at the young folks these days.----Their mechanical smarts is on a decline.

 

[ahicks]

As a young technician I used to keep old impellers to honestly show the old folks why they need to install a new one.---To save them $$$$ big time.-----Not any more.----I just kind of chuckle at the young folks these days.----Their mechanical smarts is on a decline.

Customers get one heads up/warning from me, along with a short lesson that includes the necessity for winterizing and checking lower unit fluid in the fall.

I figure even if they have me on ignore the whole time, they might remember that SOMETHING needs to be done prior to putting it away. That'll work. They can check into it then for specifics..... -Al

 

[Sea Rider]

Impeller & Cup Issues.-

The impeller duration will depend entirely on : (1) the material with which it was built. Some manufacturers employs plain rubber compounds other elastomer compounds which lasts way more in good shape than rubber ones. A used rubber impeller when taken out their cups will remain with all their vanes stiff flexed while the elastomer ones will spring open all their vanes as porcupines. Most of them are reversible...

This is an elastomer impeller example which have way exceeded the 300 hour interval change factory stated due to micropolishing with toothpaste the cup in circular finger motion along reversing the impeller at each 250 metered run hours. With impeccable clean water paths still peed a strong jet of water.



(2) If the motor runs in clean fresh or salt water the impeller and cup will last much longer compared to an excessive degradation seen when both pumps water with high sand suspension, extremely muddy or river waters.

Installing a new impeller and cup is no guaranteed that the motor will pee as a teenager, depends on how clean or not are all the water passages inside any motor. I've seen both changed with very little avail in high hour used salt motors.

Before installing a new impeller in a new or used cup can pre lube both with soapy water, standard cooking oil, olive oil, water based Love Lube, press firmly down the impeller housing on the impeller while rotating the drive shaft CW till fully seated, bolt it and that's it.....

Happy Boating​