1961 Merc 400 Impeller Change Challenges?

[lindy46]

So I got the tool to remove the water pump cover, and am ready to attempt the impeller change. Any tips, tricks, secrets I should know about when attempting to remove the lower unit? Apparently there is no shift rod to disconnect on a merc like on a Johnnyrude. So is it just a matter of removing the bolts? Or is there more to it than that? This is a 1961 45hp Merc 400.

 

[Texasmark]

Re: 1961 Merc 400 Impeller Change Challenges?

Some Mercs just have bolts on both sides, like 2 per side. Some have one per side and one up front and one under the trim tab....you have to pop the plastic cover at the rear of the mid section (on top just above the trim tab), to access the screw holding the tab on.....if your engine has a trim tab. Removing the tab allows you to look up under the rear of the lower unit where the tab was mounted and you have access to a hex socket screw.

Gear shift should be in R (so that you can rock the driveshaft by rocking the prop when reassembling).....don't move the shift lever nor shift shaft (the short small diameter rod at the front of the lower unit) while unit is apart so that you can put it back together and the shifter will be set up properly.

Pay attention to the copper tube and any gaskets on it and insure it re-enters the hole in the bottom of the block made to accept it.

Pay attention to the direction the impeller blades are bent and bend the new ones in the same direction upon installing...a little soapy water helps. Also pay attention to the impeller it'self. There is a "key" in it that locks it to the drive shaft and if you don't get that key back in it won't turn when the engine turns.

Don't put a big blob of grease on either shift or drive shaft splines as big blobs of grease can prevent them from mating properly when you reassemble. Greasing is the thing to do, just put a thin film on it; like put it on and then wipe it off.

HTH
Mark

 

[lindy46]

Re: 1961 Merc 400 Impeller Change Challenges?

Thanks, Mark