65 horse Merc problems changing Impeller

syver

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Joined
Jun 9, 2012
Messages
8
Last week I had my "new" boat out, a 1972 Larson, with a 65 horse Mercury on it. After about 2 hours the Merc overheated and we were towed into shore. I decided that the impeller had to be changed so I bought that and a thermostat. This is the first time I have tried to do anything with an outboard. I got the lower unit off but, I have had trouble getting the housing for the impeller off. I am able to get the front but the back seems to be very stuck and I am afraid to force or pry anything.
100_1046.JPG

The area stuck is right were the arrow is, I cannot get down to where the gasket is to try and pry it apart. Should I try to force it or is there some simple way to get it to release from that bolt area? Also, just infront of that I believe is a little piece that will shift it into gear. I think that it is chipped on the edge. Is that normal? It seemed to shift okay before I took it all apart. Thanks, Roger
 

syver

Cadet
Joined
Jun 9, 2012
Messages
8
Re: 65 horse Merc problems changing Impeller

Last week I had my "new" boat out, a 1972 Larson, with a 65 horse Mercury on it. After about 2 hours the Merc overheated and we were towed into shore. I decided that the impeller had to be changed so I bought that and a thermostat. This is the first time I have tried to do anything with an outboard. I got the lower unit off but, I have had trouble getting the housing for the impeller off. I am able to get the front but the back seems to be very stuck and I am afraid to force or pry anything.
View attachment 151305

The area stuck is right were the arrow is, I cannot get down to where the gasket is to try and pry it apart. Should I try to force it or is there some simple way to get it to release from that bolt area? Also, just infront of that I believe is a little piece that will shift it into gear. I think that it is chipped on the edge. Is that normal? It seemed to shift okay before I took it all apart. Thanks, Roger

I Made It!! sort of.. I got everthing apart, changed the impeller now I just can't get the lower unit back together. I had it in Neutral when I took it apart, it sounds like I should have had it in forward. How do I know if the lower unit is in forward? Right now turning the prop does nothing so how can I change it to forward?
 

Wingedwheel

Lieutenant Junior Grade
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Jun 16, 2009
Messages
1,071
Re: 65 horse Merc problems changing Impeller

You should have the motor in Neutral to re-install the LU. Make sure the shifter is in neutral and the LU as well. If your prop spins freely both ways you're good to go. Sometimes the drive-shaft splines don't line up exactly how you took them off, so if you have someone to help they can turn the flywheel while applying upward pressure on the LU. I'm able to do it by myself, but I have long arms too lol. Just be patient and everything will go right back together. Also make sure the shift-shaft is lined up with the coupler and the pick-up tube is in the right spot to slip into the water-pump housing. good luck!
 

sutor623

Rear Admiral
Joined
May 23, 2011
Messages
4,087
Re: 65 horse Merc problems changing Impeller

That piece you refer to is the reverse locking cam. It helps keep the motor locked down when going into reverse. Yours still looks okay, but why not change it now that you are in there. As far as the waterpump housing, it got hot when you overheated, and more than likely heated itself shut. Do what you have to do to get it off (even if that means breaking it) because more than likely you will need a full waterpump now, not just an impeller. They are plastic and if they shift or reshape then the impeller will not form the vacuum that it is supposed to. A rubber mallet is a must in the world of lower unit maintenance.
 

sutor623

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May 23, 2011
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Re: 65 horse Merc problems changing Impeller

Oh nevermind dude, just read your second post.....
 

syver

Cadet
Joined
Jun 9, 2012
Messages
8
Re: 65 horse Merc problems changing Impeller

Thanks to both of you. I was pretty frustrated last night but I will give it another try. I was wondering what that piece was sutor623, and you are right, I think that i will just replace it.

Since I was in Neutral, Wingedwheel, I was afraid that I had really messed up. I appreciate your suggestions and hopefully I will be able to get out onto the water again.

Thanks!!
 

syver

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Joined
Jun 9, 2012
Messages
8
Re: 65 horse Merc problems changing Impeller

I got everything back together and put the muffs on and tried it out. It just did not want to keep on running it would start up and then die again in about 5 seconds. Maybe it is time to bring it to someone that knows what to do. So tomorrow I think that It will be going to the Marina. I just hope that they don't laugh at the old boat that I am bringing in for them to work on. Thanks for all of your help!
 

aussieflash

Lieutenant Junior Grade
Joined
Feb 5, 2011
Messages
1,004
Re: 65 horse Merc problems changing Impeller

Do a compression test before you go and let us know.
 

syver

Cadet
Joined
Jun 9, 2012
Messages
8
Re: 65 horse Merc problems changing Impeller

I brought it to the mechanic today. He started it up and it ran like a champ, when I couldn't even get it to keep running last night. The other thing that I had done was have the lower unit it a different gear than the top, so he is going to fix that for me and check the whole thing out. Hopefully I will be on the water this weekend for Father's day when my kids are coming here. Thank you all for the help!!
 

sutor623

Rear Admiral
Joined
May 23, 2011
Messages
4,087
Re: 65 horse Merc problems changing Impeller

I brought it to the mechanic today. He started it up and it ran like a champ, when I couldn't even get it to keep running last night. The other thing that I had done was have the lower unit it a different gear than the top, so he is going to fix that for me and check the whole thing out. Hopefully I will be on the water this weekend for Father's day when my kids are coming here. Thank you all for the help!!

Man, take some test runs before you take the kids out!! If you have a little kicker to stuff in the bow Id do that too. I put about 20 hours on my '67 Merc before I even thought about leaving the dock without my backup. That thing stranded me twice. Thats not going to happen again if I can help it!
 

syver

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Joined
Jun 9, 2012
Messages
8
Re: 65 horse Merc problems changing Impeller

Man, take some test runs before you take the kids out!! If you have a little kicker to stuff in the bow Id do that too. I put about 20 hours on my '67 Merc before I even thought about leaving the dock without my backup. That thing stranded me twice. Thats not going to happen again if I can help it!

That is a good idea, it wasn't too pleasant being towed in the last time. Luckily someone my son-in-law knew came by and offered their help. Even just stuffing it in the bow could be a life saver, as you stated.
 

sutor623

Rear Admiral
Joined
May 23, 2011
Messages
4,087
Re: 65 horse Merc problems changing Impeller

Yeah, I have a 4hp on my starcraft. The 65hp goes 32mph, the 4hp goes 4-5mph. But the electric on a windy day has not a chance!! P.S. I added boaters insurance to my car insurance policy, and it protects against injuries and tow accidents, but the big thing for me was that it covers a tow back to shore for up to $500!! It only costs me $20 a month. Just something to consider.....
 
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