2004 Mercury 25hp EH Impeller

Hi, bought a new 2004 Merc 25hp EH for an old but new-to-me 1648 flat bottom sea nymph traveller.

Potentially major issues in the powerhead aside for now, I'm trying to get it to pee properly. Currently, it is not peeing at all. The guy I bought it from said he had put a new impeller in it, but could not get it to work. I don't have full trust in him, so I decided to take a look today. The impeller is new. I'm looking for opinions on the water pump / impeller. Specifically, could the absence of the washer or gasket (part no 12-86645 1) cause the impeller to not pump a drop. That is all I could notice missing. https://www.boats.net/parts/search/Merc/Mercury/2004/1025301CD/GEAR%20HOUSING%28DRIVESHAFT%29%20%282.25%3A1%20GEAR%20RATIO%29/parts.html

My 15hp Merc does the typical Mercury dribble until the thermostat fully opens and it pees strong. Guess I head there next. Thoughts? Some pics from today:







LU oil:


Thanks,
Mark

I've never seen a new impeller that the veins don't straighten out.I would put in a new impeller.Your lower oil looks good.I would hook a hose to the tube that goes in water pump & flush motor out to make sure there is no obstructions.Check your pee hose to make sure it isn't clogged also.Make sure the key for the impeller is positioned right.
I have the same motor.

Crazy
Thanks. I did check the pee hose yesterday, all good. The impeller key is good and locked in the right spot on impeller. The impeller seems big for the pump and crammed in there, but the part # matches up. Will get a new one. I will try you suggestion on flushing tube. Read last night some guys suggest removing thermostat and seeing if it pees then.

So, I ran air through the hose from where it connects to water pump and it comes out telltale strong. There is no obstruction that would block all water.

I took thermostat out and tested to see that it opens in hot water using a candy thermometer. Thermostat opens well. In the process of this, I realized that some water would bypass the thermostat when closed (the mercury dribble). Currently, no water is getting up and out. So, trouble shooting suggest it must be waterpump?

I put it all back together hoping that messing with the impeller would have gotten it right. It still isn't peeing at all.

I guess my next step is to order a new waterpump kit. Hope that gets it right. If not, I'm stumped.

I did notice the key (part no 85119) is small for the slot it is cut for. But I can see it turning the impeller when I turn the shaft. See pic.



thermostat, dirty, but cleaned up and opened up on the stove.

Another thing you can do to confirm water pump is working is when water pump is assembled spin drive shaft with drill with lower in barrel of water.Make sure you spin the same direction as motor spins..

Craig,
Thanks for your help. I will try that. It will be a few days before I can get back to it. Going to order some parts in the meantime. I will post resolution to the problem when I figure it out. Thanks,

Mark

Craig,
On your motor, does part keyed 43 (#29804T) slip over part keyed 27 (#85090). If so, I am missing part #29804T.

At the top of my post, the first pic after my motors serial number, you'll see what I am reading to be part 85090. The picture shows the only piece there currently. This is the part I assumed was mating to the copper feed pipe.

Does part 29804T serve to make this connection water tight? If so, that could be my problem. Perhaps the copper pipe is not mating to my waterpump well?

Ordered some parts today, should be here by the weekend.

M

Sorry, I don't remember that plastic piece on mine.Just make sure the tube that goes up the lower goes into that rubber grommet.The plastic piece might be a guide for the water tube when installing.

Also, the basics haven't been covered here. Am assuming you are testing on either the hose or in a tank.
If in a tank make sure the static water level is several inches above the water pump location. Can't tell you how many folks have posted here with this issue only to find out that the answer was this simple.
If on a hose try squeezing the "muffs" together around the water inlets (if your inlets are on the side of the gearcase). If they are the ones with the plastic tensioner, throw those as far as you can and buy the ones with the metal tensioner.