Impeller Question

Michael T

I was getting high raw water pressure readings on my Port engine.  It is a 2014 Mercury 8.2 Magnum - closed cooling with raw water cooling in the heat exchanger. In the end it turned out that the sensor was bad and it was replaced. Before that was realized the technician replaced the impeller in the raw water pump. It looked like he had to force the impeller in. I asked him if he had gotten it in backwards. He said there was no such thing and anyway if it did go in backwards the fins would just reverse. Today at the end of a 7 day trip I got critical low water pressure warnings on my vessel view for the Port engine - and a warning to return to my slip immediately. I shut the engine off right away and docked the boat.  When I got the boat secured in the slip I restarted BOTH engines. There were no more alarms from the Port engine BUT it was operating at half the water pressure of the Starboard engine all the way from idle to 2000 RPM. FINALLY  - the question. I just looked at the impeller the tech took out weeks ago. There is no question that the fins are all pre-formed in one direction. Is he right that if he installed it "backwards" that the fins would just bend in the right direction or is he full of cr*p - 'cause it sure doesn't look like the fins will "bend" to me. Advice appreciated.

mvn

How old is the impeller you are looking at?   What you are probably seeing is the "set"  the vanes have taken over time.   And yes,  they are hard to bend back.   When new,  it takes a lot to get an impeller into a housing as the vanes are straight.  Depending on the concentricity of the impeller to the housing,  the vanes should orient themselves correctly.....  Or I could be wrong! 

Mark

Michael T

Thanks guys! The engine is a 2014 and has about 100 hours on it so the impeller was that was replaced was "new".  The technician was "experienced" and I would hope that he checked the housing for signs of wear when replacing the impeller. He said the impeller he took off was okay but he might as well replace it while he had the water pump off as he was going to change it at this winterization anyway. The only work that has been done on that engine was to replace the impeller. I guess my question will be if an o.e.m. impeller was used and maybe we should check the raw water sensor as the starboard one was faulty. The weird thing is that the engine is NOT overheating!

Michael T

Many thanks Al. I'll pass that on to the tech! I'm pretty decent at handling boats but docking a 360 in a cross wind with one engine is a bit unnerving for me!!! I need to get this fixed before we head through the locks to the boat's winter home. I don't want the Engine Guardian System shutting my port engine off just as I enter a lock in a crosswind - LOL

Michael T

AL- I know you are always busy - do you have a fast access to this answer. Mercury at Fond Du Lac said the proper PN for the water pressure sender I need is 8M6000623. Is this the low pressure sender rated to 20 psi that you use? THX Michael

MarkB

Yeah, I agree with others. From the pictures I have seen a new impeller has straight vanes, and only the used ones have curved vanes due to use. I'd imagine a new one would be tight to get in due to the vanes being straight.

Michael T

Thanks to all of you for the comments. I trust and like my tech but he does get things screwed-up from time to time, after all - like all of us - he's only human. That's said, I like to have as much info as possible before discussion options with the marina. NO one knows Rinkers like the combined knowledge of this forum :-)

TonyWalker

Try putting a ty-wrap or something similar around the impeller to pull the blades in a bit.  Insert part way and remove the ty-wrap and push in the rest of the way.

Michael T

Thanks AL and Tony - as usual - priceless info here!

Michael T

.....and they say you can't have any fun at work these days! My only question Al - has your Human Resources Department (likely your Admiral) approved of this process?????