Changing Water Impeller Rude 40HP Lark VI 1964

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Jul 6, 2006
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1964 Rude Lark VI:

My OEM manual show the loaction, but not the procedure for the changing. In short what would I need to open up to get at it? What is the time estimate so I can evaluate that against the manual diagram....dont want to remove too many parts... I can tell that it is located on the main drive shaft..but which cover do I remove??

Thx

Sam
 

Paul Moir

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Re: Changing Water Impeller Rude 40HP Lark VI 1964

1 quick question: Manual shift or electric?
 

Paul Moir

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Re: Changing Water Impeller Rude 40HP Lark VI 1964

The first time you do it, it'll take the better part of an evening assuming everything goes well with no broken bolts. The next time will take a couple hours, perhaps less. Third time an hour or less. :)

Lower unit removal procedure:

1) Disconnect the shift wires next to the engine near the back.

2) Remove the back half of the midsection's exhaust shroud. There will be a pile of phillips screws that need to come out. If they're proving to be a hassle, invest in an inexpensive impact screwdriver. The kind you hit with a hammer.

3) Remove the access plate on the starboard side of the forward part of the exhaust shroud, and then remove the plate behind it. Snake out the electric shift wires so they're free. Soap helps. Do yourself a favour and first tie a string to the wires so you can use it later to feed the wires back up into the engine compartment.

4) Unbolt the lower unit and pull it straight down. You may have to force it with wedges if the driveshaft splines weren't properly greased. Don't worry, the only parts that can break are cheap.

Installation is the reverse of removal, but be sure to grease the splines and replace the o-ring on them if it's bad. Also, coat all the screws and bolts with gasket sealer or grease before re-installing. This will keep them from corroding in place.

Goop is basically what holds the wires into the lower unit, so be careful not to pull hard on them.

That will expose the water pump. Does your manual cover it from there?
 
Joined
Jul 6, 2006
Messages
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Re: Changing Water Impeller Rude 40HP Lark VI 1964

I have the OEM "rude" manual which is engine specific. It only speaks of the impeller, abosolutely nothing else on replacing. If you have more info. to impart please do so.

PS; The manual seems very good in regards to troubleshooting and other stuff...seems that changing an impeller is considered a routine maintenance thing that all "good" boaters know how to do intuitively...:%

ALSO: I tried to get thermostat cover off and noticed that it still has original OEM paint on it. They are on tight..so I presume that the screws on the exhaust cover will be so as well...I just bought a hand impact driver and tried it..I hit it med-hard..not to hard..and no action...I am afraid to hit it harder since the casing seems to be all aluminum...HOW HARD DO I HIT IT???

I am listenting...many thanks...

Sam
 

Paul Moir

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Joined
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Messages
6,847
Re: Changing Water Impeller Rude 40HP Lark VI 1964

I use a 3lb hammer. I believe those are held in by 1/4"-20 screws - your normal impact driver will not twist their heads off. You may end up having to apply serious heat though there are some plastic parts in there that may end up fried. Not a big deal though - start with light heat and work up.


Once you have the lower unit off, you'll be looking at the water pump on the top of it. It's secured with three screws. Once you take them out, you'll be able to lift the water pump housing off revealing the impeller. The impeller can then be lifted off the driveshaft.
When the housing is off the water pump, it's possible to pull the driveshaft right out of the lower unit. You should avoid doing this as bits of dirt can end up falling into the gearcase. But if it happens by accident, don't worry. Just put it back in and turn it a little until it drops to it's normal height.
Beyond the housing and impeller is the stainless steel wear plate. If you're replacing that too, remove it. The manual says to seal the new one to the lower unit with sealant but you can consider that step optional. There's no sealant between the wear plate and the housing.

When installing the new impeller and housing, first lube the impeller with a little dish soap. After it's installed, lower the housing on. When you bring the housing down to the impeller, turn the driveshaft clockwise so the vanes of the impeller compress in the right direction. Continue turning the driveshaft as you tighten the three screws to catch any binding.

When you reinstall the lower unit, you'll have to first line up the driveshaft and then the two water tubes with the water pump housing. This task is obvious but tedious. Sometimes it's worthwhile to have a bolt on hand to "hold" the lower unit in place while you line things up.
 
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