I've got a WF4 super twin. I finally got around to rebuilding it. Pulled the heads to clean the rust out and one ring on each piston broke during install. Each ring lost a 1/2 inch. Now I have the pieces in hand and they are not in the motor. Now can I run the motor with each piston missing a 1/2 inch from only one ring? Im thinking no but I figured I'd ask. And if no is the answer, then where do I go to find a set of new ring?
I have heard of people running them with only two rings installed at the top of the piston.
I would not leave the broken rings on the pistons.
The motor uses the same rings as the Mercury KE4 MARK7 and these are available from www.oldmercs.com
I would spend the money on two new rings. They are cheaper than the gaskets.
Well now I have to replace the head gaskets and the cover gaskets since they got a dab of liquid gasket to help seal.
Piston rings Mercury part # 39-21665. Used on the 5.5 cu in. singles and
11 cu in twins with 3 ring pistons. Also used on Merc 39 and Merc 60
If you have a local Mercury dealer they may still stock and perhaps have
some other items...has to be a long time Mercury dealer though and maybe
they pitched all the old junk years back.
Cast Iron will only flex so far and no farther...a lesson I have had to learn
myself. When installing pistons into cylinders the gap at end of rings
has to center on the locating pin in piston groove. If ring overrides the
locating pin bad things are sure to follow and soon. Service instructions
call for removing rings before removing piston from rod and to install
rings after replacing piston on rod. Rings and piston are easily damaged
when removing or installing piston pin...I paid the tuition to learn that
You can get the rings HERE, as well as other parts too.
The cousin to the Wizard WF4 is the mercury KD4.
I would think that broken rings would score the cylinder wall.
I like to put grease or anti-seize on one side of the gaskets so that you can take it back apart in the future in case the gaskets are discontinued. Just my 2¢.
I got an Email from Joe Poole at Ferguson-Poole, Inc. reminding me that they have some hard to find parts for the WF4 also. Here is the Email. I hope Joe doesn't mind my including it here as it might help others to find parts they may need also.
Long time since I spoke with you last. Possibly this is unneeded as you apparently prefer OldMercs, but we now have some stock of gaskets specific to the WF4 and WG4 models that I do not know of anyone else offering. These can be viewed on either our "Exhaust Systems" page: http://fergusonpoolemarine.com/exhaustsystems.html (third item down from the top of the page), or on "Outboard Motor Parts": http://fergusonpoolemarine.com/outboardmotorparts.html (about 15% down from the top of the page, and about 60% down for another). Note that as they were produced a few years later, there are also some other differences between a Mercury KD4 as well. We do have the factory parts manual for these, as we do for any other vintage Mercury or Mercury produced Wizard. Thank you for your attention.
Joe Poole, Jr.
Ferguson-Poole, Inc. (Marine Sales & Service since 1951)
(770) 597-5992 Cell
The only reason I send folks to Oldmercs is that they list parts under each model number and it is a little easier to find things. I'm sure Joe would be glad to help find parts for you if you contact him above.