Mk 5 & Mk 6 Seals

[Buccaneer]

Working on my Mark 5 and trying to figure out bearings and seals.
"Most" replacement parts appear to be the same as the Mark 6
I went thru last year. The "Water inlet cap" (that bolts up under
the power head) appears the same between the two Mark engines.
The seal shown on the parts diagrams for the Mark 5 says
"Crankshaft seal", and on the Mark 6 diagrams say
"Water inlet cap seal".
It appears from looking at the engines that the seal can only
go around the crankshaft on either engine, as there’s no room
in the cap for a seal, and still have it bolt up to the crankcase.
Anyone concur that this is correct, and it’s just a change in
terminology between the Mk 5 & 6?
Anyone ever find an aftermarket replacement for the
26-22580 OIL SEAL in question? I’ve had no luck looking
in the SKF or Timkin seal charts.
Shaft size .687, OD 1.000
Thanks!

Prepare to be boarded!

[billw]

I have never actually had the two in my hands but I have noticed that, too; and I always believed it to be a terminology thing. Here are some:

http://stores.outboardparadise.com/26-2 … l-nos-new/

Long live American manufacturing!

[Buccaneer]

Bill, I will probably end up getting a NOS seal, but was
hoping to find a new one. I always wonder how good
those 40 year old NOS seals are.
I looked at the seal in your link, and when enlarged
you can read it’s a CR seal, #MA-5723.
That doesn’t compute to SKF or any other current seal
that I can find.

Prepare to be boarded!

[dan-in-tn]

McMaster Carr shows a .669 X 1" X 3/16" buna N shaft seal that should work. 11/16" is .6675, so that is just .0015 over. I think a single seal was like $8.61. Check that out under ring seals. They have just about everything.

Dan in TN

[dan-in-tn]

Sorry, I got the measurements wrong, but check them anyway. They have just about anything you need in the way of sizes. Don’t forget metrics!

Dan in TN

[Buccaneer]

Thanks Dan, I didn’t think to check McMaster.

Prepare to be boarded!

[fastjohn]

SKF 6720—Bore .688, OD .999, Width .188

[Buccaneer]

Thanks John! I never thought to search for a seal with an
OD of .999 !

Prepare to be boarded!

[jeff-register]

Buckineer,
The KF5 requires removal of the crankshaft to install the seal. The seal sits in the block just below the bearing. Both require to be installed from inside the block & requires a little recess below the inside deck surface. This MUST be set accurate in order the end clearances to be correctly. The seal rides on the crankshaft surface inside the block. Yes the water line adapter has three phillips screws & a new gasket. Leaving the exhaust housing in place use a 24" long 1/4" extension to center it in the crank, then install the screws.

[Buccaneer]

Jeff, Is the KF5 the "Super 5", predecessor to the Mark 5?
Guessing they’re similar anyway.
I got the water inlet cap screws out okay, but
couldn’t pry the cap loose down that long tube,
so I removed the long swivel tube. Much easier
to clean the gasket surfaces, pressing functions,
installing the new seal, etc…… went thru all this
last year with a Mark 6, but couldn’t remember if
there was suppose to be a seal in the water inlet
cap and on the crank. Believe I just seen one of your
old post saying a SKF 4912 seal would fit in the cap.
Do you remember anything about that? Thanks,
Buccaneer
P.S.- I believe (on the Mk 6 anyway) that the seal
OD is bigger than the lower bearing OD, and that
the seal is installed from the outside….. but seems
like I pressed both out from the inside?

Prepare to be boarded!

[Author]

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