66 Merc 500 Questions

[pksbldr]

I am replacing the water pump and have some questions that I hope someone will answer. When I put water directly into water tube in driveshaft housing, no water exits through the tell tale hole on side of motor. It does exit out the top hole with the plug removed so I know water is getting to the motor. I am assuming the hose to tell tale hole is plugged: 1. Can I use air pressure through the threaded hole in top of water jacket in an attempt to blow out lines. Also, when I broke the lower unit free, there was a lot of gritty sand around the outside of the water pump, exhaust outlet tube and the shift linkage on lower unit: 2. Did this sand have to travel through pump to get inside the housing? Just curious how it got inside housing. 3. Should there be a gasket between driveshaft housing and lower unit on reinstallation? 4. While it is apart, is there anything else I should be concerned abou?. Sorry this is long but thanks for any assistance provided.

 

[Yepblaze]

Re: 66 Merc 500 Questions

1 you can use air or water under pressure into the pee hole to back flush the line and it's port. Sometimes a probe is involved to loosen crud.

2 it is not uncommon to find some sand around waterpump housing. Not usually a big issue. Hose it off and get down to business with waterpump service and pee hole/line clearing.

3 no gasket between lower unit and "midsection"

4 upon reinstallation make sure the lower unit and shifter mechanism is in the same position (at the splined connection) and stays that way during the process.
Otherwise all it will have if forward gear, and no neutral or reverse.

I prefer to use neutral, but the lower unit has a tendancy to sort of pop into forward during the process and might take a few tries to get it right. Sometimes it takes a slight turn of the flywheel to align the drive shaft splines too

 

[pksbldr]

Re: 66 Merc 500 Questions

Thanks for the info. I am assuming it doesn't make any difference which spline aligns on driveshaft as long as they are aligned so units can come together? Also having difficulty removing lower half of waterpump. Any tricks? BTW, impeller was really beat up with a couple of fins gone. Anyway I really appreciate the knowledge and help out there. Thanks again.