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Impeller question

T

the_beave

Member
"I just picked up a 1965 Merc

"I just picked up a 1965 Merc 39. It runs good but I'm not sure if the water pump is working or not. Where should the water be comming back out at? Is it the same place as the exhaust? Also if I have to replace the impeller, where is it and how do I change it? This is my first outboard so I'm not really famillar with them yet!
Thanks"
 
The foot needs to come off to

The foot needs to come off to get to the impeller. I don't remember if they had a tell-tale in '65 but is should spray out on the exhaust nostrils. The block will get red hot right away if the impeller is dead.
 
"Arron, the lower unit itself

"Arron, the lower unit itself is only held on by 2 nuts.

Although changing out the impeller is not a difficult task by any means, you still really should have at least a repair manual (such as Selocs) to take you through the various steps."
 
OK I took off the lower unit t

OK I took off the lower unit today and sure enough the impeller was toast. I got my hands on a new one and put it in. I then put everything back together and as it was getting dark I could'nt launch it so I filled a large bucket (the water was just above the lower fins) and put it in and fired it up but I still did'nt seem to get any water to come out of the exhaust port. Is it posable that it was not deep enough in the water or could something else be wrong? I am sure that water flows through the impeller but not sure if it is going up the line to the motor . I took it apart a couple of times and am sure everything is together right. Any ideas would be great!
Thanks
 
O.K. You may have to drop it a

O.K. You may have to drop it again and run a garden hose on the copper pipe. Water will come out of somewhere for sure. It should come right out the exhaust pipe. Unless the copper pipe has a hole or the pipe grommet under the P/H is bad. If not the next step is to lift the powerhead and see what is going on under there. The pump turns clockwise. The stack goes gasket/plate/gasket. You put the impeller on the shaft and and turned it clockwise and shove the lid on right? You did put the little keyway back in the pump right? I gotta ask. Sorry.
 
I ran a hose on the copper pip

I ran a hose on the copper pipe but the water just all came back out the bottom with nothing out the exhaust.Wasn't sure if anything was going up as the pipe is so much smaller than the hose! How would I check the upper end of the pipe? The impeller is on with the keyway and turns with the shaft. Which gaskets are you talking about? There were no gaskets on the impeller housing! Should there be? Sorry if these question sound stupid but I have never worked on a outboard before.
 
"Oh, If that is the upside dow

"Oh, If that is the upside down pump than there won't be a gasket. Sorry, there will be a metal cup in the housing with a metal plate. I am going from memory. If nothing came out the exhaust than no water went in the motor. Try to reuduce the hose size to get a better fit if you can. As best you can seal it over the pipe. The pipe can only be checked with powerhead off."
 
might be best not to force the

might be best not to force the old impeller pieces into the engine. is there a way to use compressed air or water to blow the tube clear from the other side. I don't know that engine or I would be more helpfully
 
"OK so I pulled the lower unit

"OK so I pulled the lower unit again and blew air up the pipe but was only getting a small amount of air out of the exhaust hole but there was some flow. I then fought with and was able to remove the screw on the bottom of the main housing marked "fresh water flush" and found it to be blocked with a white hard substance that as I poked at it, it turned powderish. I then removed a screw type plug right above the sparkplug and there are signs of the same type of stuff in there but not as bad! Would this indicate silt/crud bulid up behind the water jacket cover? I don't really want to pull it off if it can be avoided! If I run the hose somehow into the fresh water flush hole would this be enough to clean it out?"
 
"The only way to get at the to

"The only way to get at the top of the tube is pull the powerhead.

You could probably get the water-tube out from the lower end, but would be more than a chore to try and get it back into the exhaust plate without removing the power head.

If you do pull the head, first make sure that you can get ahold of a new powerhead-gearhousing gasket, they can rarely be saved."
 
"To get rid of that "white

"To get rid of that "white" substance you can try a solution of water/vinegar (50/50). It won't hurt the aluminum parts and does a (fair) job of cleaning the build-up. Just force it in where ever you can.

Ultimately though, you may have to pull the cover and give it a good clean out..."
 
You need to accept the fact th

You need to accept the fact that an old motor needs work.There is a plastic/ nylon washer at the top of the water tube and it is likely blocking water flow to the block.Removing the water jacket covers is really simple once the powerhead is off.No point in cranking and hoping it will fix itself.
 
"Ok so I flushed thru both the

"Ok so I flushed thru both the fresh water flush screw and the screw above the spark plug and got lots of flow down thru the midsection but nothing out of the hole on on the back of the case that the exhaust comes out of! I then said the heck with it and pulled the cover off of the water jacket. It wasn't overly bad. I then put the hose on the copper pipe again and there is a slow flow of water comming up thru, but there is water. A couple of times it coughed like it was going to start gushing, but never did. Is the powerhead the actual engine? Is it hard to pull it? Is there anything special I need before deciding to do this? There is a plate under the back end of the engine, what is under that? Should my water be comming out of the hole on the back bottom of the case or does it only go out down thru the midsection like it is?
Sorry for all these questions but would like to know what I'm in for before I get into it!
Thanks again!"
 
Just take it apart ( 6 nut

Just take it apart ( 6 nuts ) is all that holds the block on. There really is nothing to it.
 
"I pulled the powerhead today

"I pulled the powerhead today and sure enough the plastic gromet was melted shut! Everything else seemed fine with good flow thru the motor. Went and got a new gromet, powerhead gasket and water jacket cover gasket and all is now back together. Now I just have to wait for the wind to die down so I can take it and give her a try. Will let you alll know how things work out as soon as I can. Thanks again for all the help!"
 
"Ah-ha! I knew it all along. <

"Ah-ha! I knew it all along.
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Had it out this evening for a

Had it out this evening for a test run and it worked great! It had a good flow out the exhaust hole and seemed to run fine! Ran strong and kept cool. Will give it a good run on Sunday if the weather is good!
 
Finally got out today for a go

Finally got out today for a good run. Was out for an hour and a half and everything was great! Too bad it didn't have more speed but it sure beats rowing...lol! Thanks again and happy boating!
 
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