HELP~HELP~HELP~HELP~HELP~HELP~HELP~HELP~HELP~

HOW DO YOU KNOW WHICH MERCRUISER YOU HAVE AND WHICH IMPELLER KIT YOU NEED?  THIS IS FOR YOUR INFO.

OLDER MERCRUISER DRIVES HAVE A LIFTING RING ON THE TOP OF THE TOP CAP.

THESE ARE CALLED PRE ALPHA OF PRE 1985 YEAR.

THE UNITS FROM 1972 THRU 1985 ARE CALLED NUMBER ONE UNITS.  

THESE UNITS ARE DISTINGUISHED BY THESE TRAITS.

1) THE DRIVE SHAFT HAS THIRTEEN SPLINES ON THE TOP AND A 3/16 PIN ON THE TOP

     OF THE SHAFT WHICH IS SPRING LOADED TO HOLD THE PINYON GEAR INTO THE

     0THER GEARS.  

2) THE BASE OF THE WATER PUMP HAS A CIRCULAR PART WHICH STICKS INTO THE LOWER

     HOUSING WHICH MEASURES 2-1/4" AND IF PLACED UP SIDE DOWN THE OUTER EDGE HAS

     A RIDGE STICKING UP.WITH A GAP OF THE CIRCLE  AROUND JUST ABOUT 1/2"

3)  THE BOLT THAT HOLDS THE TOP ON IS A MACHINE BOLT WITH COARSE THREAD.

4)  THE COMPLETE KIT TO FIX THE #1 PUMP IS IM091C1 OR IM091 FOR THE IMPELLER KIT

5) THE UPPER AND LOWER UNITS ARE CONNECTED WITH FIVE STUDS AND SINGLE NUTS

     ALSO ALLEN BOLTS.

OLDER UNITS ARE CALLED #1 A-B-C AND ARE ALMOST THE SAME EXCEPT THE DRIVE

     SHAFTS HAVE ONLY 8 SPLINES AND ARE ABOUT ONE INCH SHORTER, BUT THE SAME

     PUMP REPAIR KITS ARE NEEDED, HOWEVER THE OLDER BASES HAD A SIDE FLUSH

     HOLE WHICH LINES UP WITH A HOLE IN THE SIDE OF THE HOUSING NOT LONGER USED.

 

AFTER 1986 THE UNITS ARE CALLED ALPHA WITH DIFFERENT FEATURES.  THE MOST

TELLING OF THE DIFFERENCES IS THAT

1)THE PRE LOADED SPRING ON THE TOP OF THE DRIVE

    SHAFT IS GONE. THIS IS THE MOST EVIDENT PART OF THE DRIVES IS IMPORTANT.

    THE SECOND DIFFERENCE IS THE TOP CAP, THE LIFTING RING IS GONE AND THE CAP

    IS FLAT.

2) THE ROUND PART OF THE WATER PUMP BASE IF FLAT AND MEASURES 2-3/8"

3) THE SCREW WHICH CLAMPS THE TOP ON THE BASE IS A SHEET METAL TYPE WHICH

     FITS A 5/16 WRENCH, NOT A MACHINE BOLT.

4) THE IMPELLER KIT IS STILL IM091 BUT THE COMPLETE PUMP KIT IS IM091CA WHICH IS

     DIFFERENT BECAUSE OF THE BASE IS NOT THE SAME.

 

AFTER THE 1992 YEAR,  MANY CHANGES IN THE DRIVES OCCUR.

1) THE UNIT IS CALLED ALPHA GEN II

2) THE IMPELLER IS LARGER AND MORE FLOPPY STYLE IMPELLER

3) THE UNIT IS DISGUISHED AS THE WAY THE UPPER UNIT IS CONNECTED TO THE

     LOWER,.  INSTEAD OF STUDS FOUR BOLTS WITH NUTS WITH BOTH ENDS VISABLE

     AND TWO WRENCHS ARE NEEDED TO REMOVE THESE BOLTS AND NUTS.

4) THE IM1811 KIT FITS THE GEN II PUMPS.

 

BEYOND THE ABOVE PUMPS ARE THE BELT DRIVEN FRONT PUMPS. THE OLDER CALLED THE

BRAVO PUMP IS MADE OF I/2 BRASS BODY AND A PLASTIC COVER THE NEWER PUMPS ARE

CALLED THE GEN 7 PUMP WHICH IS  BRASS WITH NO PLASTIC.

 

THE OLDER PUMP HAS A 5/8 " SHAFT WITH ONE SIDE FLAT.

THE MORE RECENT GEN 7 PUMP HAS A 1/2" SHAFT WITH TWO FLATS.

THE KIT TO FIT THE OLDER 5/8 PUMP IS IM3909 OR WITH NEW HOUSING IM3909H

THE KIT FOR THE BRASS PUMP IF THE PUMP BODY IS NOT DAMAGED IS IM496

 

SOMETIMES THE BRASS PUMP HAS BEEN PUMPING WITH SANDY AREAS AND THE

SAND PARTICLES STICK IN THE EDGES OF THE IMPELLER CUTTING SWIRL GROVES

IN THE BODY OF THE PUMP WHICH CAUSES THE FAILURE OF THE SUCTION SIDE

THIS WILL NOT BE CURED WITH A NEW IMPELLER.

A NEW REPAIR KIT WITH S.S. WEAR PLATES WILL CURE THE PROBLEM,  THE KIT

CALLED IM496REB WILL MAKE IT WORK AS GOOD AS NEW

GOOD LUCK

THE COMPLETE LIST OF ALL PARTS WILL BE FOUND IN OUR WEB SITE

AT AFTERMARKET .COM