Impeller pump check

[kulle]

So hopefully this will make you all LOL. Rookie mistake....took apart my upper/lower to inspect impeller. Did my due diligence and drained the gear oil. Not a drop on the floor. used the rubber mallet to separate and the lower falls down onto my oil catch gallon jug and oil all on floor ! I didnt have the lower portion of the lower drive on the top of my stand ! arggggg.

Any event, looks like i need to replace gaskets for impeller. Does anyone know the thread size for the "guide pin bolts" to use or alignment? Thanks

 

[badrano]

I just changed my impeller...full kit. I didn't use the guide pins. I placed the gaskets and plate in place and inserted the impeller in to pump housing making sure the blades were bent in the correct direction and the shaft hole of the impeller was in line with the shaft hole of the housing. Slid impeller and housing over the shaft and just needed to turn the shaft so that key lined up. I found this easier than putting the impeller first on the shaft and trying to rotate the shaft to get the housing on.

 

[harringtondav]

Does anyone know the thread size for the "guide pin bolts" to use or alignment? Thanks

The guide pins are M6 x 16. I use four socked head cap screws - 3" long. As badrano notes, they aren't necessary, but they do make the job easier. Especially for $2-$3.

 

[kulle]

thanks

 

[havoc_squad]

Compared to doing a 1990 johnson 90 hp outboard impeller kit now, the Merc Alpha One Gen 2 oudrive impeller kit I did 3 years ago seemed worlds easier and faster to do.

As long as you left a small gap over the base plate, I never seen a need for guide pins. The securing bolts worked just fine for alignment of the gasket, base plate, and impeller housing.

Guess that's a small price for not having to fuss with a bellows.

 

[kulle]

i got some m6 studs from work...glad they have a machine shop! once my gasket kits comes in, i'll have the outdrive back,then going to order OEM transom repair kit- bellows! hope that goes well.

 

[achris]

Thing is, the pins aren't just M6... The thread at the end is, but the shaft is 7mm, and that's the section the housing, gasket and plate locate on.. Using an M6 screw will have no locating benefit at all. You need the extra shaft diameter because, the screws holding the impeller housing down are already M6, the holes in the housing are 7mm.. But Merc made that all moot a few years into production of the Gen II. They changed 2 of the holes, made them oval, with the minor diameter at 6mm. So all you need to do now (if you have the later housing and plate) is make sure you put the screws into the oval holes first, then, the alignment is done.

If you have the earlier housing, plate and gasket, then you MUST use the pins, or the housing and/or plate can be hard up against the drive shaft and wear a groove in it...

Here is a photo of the pins, with full dimensions...







Chris..............

 

[kulle]

nice write up- that helps i'll check my holes.

 

[kulle]

just to wrap up my questions regarding this impeller replacement task....manual says to use some pefect seal on the one gasket before putting metal plate on. permatex high tack gasket seal should work right? its non hardening and stays tacky like perfect seal does