Help please Mercury 25 HP Twin/Mark 28? Foot Removal?

mmf

Petty Officer 2nd Class
Joined
Sep 4, 2008
Messages
136
I have an old antique Mercury 25 HP Twin motor that looks exactly like a Mark 28 Super Hurricane, but my serial number does not co-incide with the numbers for a Mark 28. My serial number is: 1498212. Mine has the "automatic" transmission just like the Mark 28 and mine also says "Super Hurricane" cast into the block. I have never removed the lower unit from one of these motors but I need to to put in a new impeller. Is there anything different about removing the lower unit from say the mid "60's" motors?
I was wandering about the little linkage on the exaust (driveshaft) housing, does it have to be loosened? I am missing the cover on this linkage too and
I need to find one. Any help greatly appreciated as I have no manuals going back past serial numbers 159XXXX.:redface:
 

mmf

Petty Officer 2nd Class
Joined
Sep 4, 2008
Messages
136
Re: Help please Mercury 25 HP Twin/Mark 28? Foot Removal?

bump
 

corm

Lieutenant Junior Grade
Joined
May 12, 2000
Messages
1,241
Re: Help please Mercury 25 HP Twin/Mark 28? Foot Removal?

Hi,
Everything is different.

Here are some posts I made before.

The impeller is in the middle of the midsection above the trunnion gear set.
You have to take the cover off the front of the midsection that has 2 or 3 screws in it to see the front nut to remove the LU.

Then LU comes off like most merc LU's do. That is the only similarity everything else is different. I would not tear it down until you have a book or you may wreck something that can not be replaced. Special tools are needed so look at them in the links below to see if you can build them or want to buy them. Maybe you can adapt tools from other industries too.
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. (if you do not want to buy one)

Some manual and parts lists I am sure there are more out there.
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.

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 & calipers for that. You need that to set the trunnion depth so you don't blow the trunnion gear set and clutch spring apart.

This is not the one hr job that the other Mercs are to do.
 
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