Merc 1962 25HP Twin

[mmf]

I just bought 2 old white cloud painted 25HP twin motors in a lot deal.
My manuals only go back to 1964 and I have not worked on this model before but I am told they are a real booger to put a water pump in.
Supposedly an "automatic" type lower unit from what I have read.
Has anyone changed the impeller on one of these that can give me some tips or do's and dont's?

 

[corm]

Re: Merc 1962 25HP Twin

Hi,
I have done a lot of them. I suggest you get a Mercury Marine manual on the engine from some where. You will need it. You will also need some special tools.
You may be able to make them from the pictures in the manual. The auto transmission Mercs are the hardest pump change anyone can do. I would try to find a old Merc Wrench that has some tools to do it for you. I used to charge 3 times the $$ to do them over a std merc. Most of the power heads need a bottom crankshaft seal in them by now too. On the upside they were a good running engine when tuned up. The engine may need new coils by now. If the outer coil cover is soft they will need replacing. It is going to be a interesting project engine for you.

 

[mmf]

Re: Merc 1962 25HP Twin

Thanks for the reply, what is an "old Merc Wrench"?
I hope I can find a manual for them. About the water pump, is it
mounted in the standard mercury position on the bottom of the driveshaft?
Also, is the lower unit removal the same as other mercury's?
Thanks

 

[corm]

Re: Merc 1962 25HP Twin

Hi,

a old merc wrench is a Merc Mechanic about 60-70yrs old. Some one who actually ran and worked on these engines. I really doubt that any younger mechanics have ever had one apart or put one together so it would ever work again.

The impeller is in the middle of the midsection above the trunnion gear set.
The LU comes off like any merc LU does. That is the only similarity everything else is different. Do not tear it down until you have a book or you will wreck something that can not be replaced. I do not want to sound like a jerk about this but I don't want to re-write a service manual from memory on this engine here in the forum. You need a manual to look at the special tools needed to see if you can build them. If you can then I'd say go for it. At that time I will be willing to help with some problems you will run into. My email is in my profile.
I would check with a older Merc Dealer to see if they would let you photo copy, for a fee, the Merc shop manual section on this engine. Be sure to get good copies of the 4 special tools you need to do the job.

manual and parts lists
http://www.eastcoastmarineservice.com/manuals.html
Impellers
http://www.vintageoutboard.com/
these guys seem to have the book
http://www.maxrules.com/timingindex.html
http://www.maxrules.com/oldmercs/timing/10.pdf
The just do not post the pages of it you need.

 

[corm]

Re: Merc 1962 25HP Twin

Hi,

Here is a site with the tools. He has a manual too.
http://www.johnsmcintosh.com/Tools.htm
pic 2,4,5, are needed. (#2 most important #5 next)
I do not see the depth gauge tool in his list but
you can use a mic for that. You need that to set the depth so you don't blow the trunnion spring clutch apart.