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19'69 40 hp water pump housing - planing and shimming with gasket?

baytonemus

New member
I'm rebuilding the '69 LU and have started putting it back together. I have a couple of Mallory water pump housings (#312612 replacement for original OMC) that came off LUs from '63 and '69. Both have fairly typical corrosion and pitting inside that doesn't really concern me too much. One has pretty serious grooves cut into the top of the inside of the housing, so that one's junk, I think. The other one had a spot that looked like someone had maybe pried in open with a small screwdriver and then sanded it smooth. Basically there was a little gap about 3/8" long that wasn't going to seal.

I went out to the local independent OB motor shop where I've bought some salvage parts before to see if they had a decent used one. The mechanic said he thought I could still use that one and took it to the sanding disc and took maybe 1/32" off the bottom.

It will be a tighter fit now, but I think that I still have enough clearance for the impeller to turn properly. When I put it in the housing a straight edge laid across the bottom contacts the edges on both sides and I can still see light between the straight edge and the brass hub of the impeller.

My other option would be to cut a gasket to put between housing and the plate. I have some fairly thin rubberized fiber gasket material that I think would work. However, if it ended up making the top to bottom fit a little too loose I'm not sure how much that would affect the amount of pressure the pump would produce.

I'd appreciate input. Thanks!
 
Re: '60s 40 hp water pump housing - planing and shimming with gasket?

In all honesty your best bet would be to go out and buy a new complete water pump kit and install it. Then you would be done with it. This stuff about(pardon the pun) sanding the housing sounds fishy to me. Those hsg's were made to certain specs an shouldn't be modified.
 
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Re: '60s 40 hp water pump housing - planing and shimming with gasket?

I know what you mean. I wouldn't have done it on my own, but these guys work on LOTS of old motors. Also, a new housing is $67. That's why I went out looking for a used one.

On the other hand, the rubber these things are made out of is obviously very flexible and meant to withstand a lot of stress.
 
Re: '60s 40 hp water pump housing - planing and shimming with gasket?

In the past I used to put those housings in a 4 jaw chuck on a lathe.-Machine a bit out of the housing and then machine a bit off the mounting face to restore it to original factory dimensions.-----------------If you have the equipment, then no problememo.
 
Re: '60s 40 hp water pump housing - planing and shimming with gasket?

In the past I used to put those housings in a 4 jaw chuck on a lathe.-Machine a bit out of the housing and then machine a bit off the mounting face to restore it to original factory dimensions.-----------------If you have the equipment, then no problememo.

Very clever! I may have to ask about that at the machine shop/welder I use. Thanks.
 
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