Re: mercruiser 165 water pump questions
no sealer is necessary on the pump housing top to bottom.
Check for any signs of melted housing top and bottom.
An impeller KIT will come with gaskets. If you need a housing you can get top and or bottom as needed. Check with your NAPA store if you get a decent discount there. If you have a plastic flush screw on the side of the drive
PNs are 18-3321 complete kit, 18-3116 upper housing, 18-3517 upper pump kit (housing, impeller gaskets etc), 18-3421 base, 18-3217 impeller kit.
NO flush screw 18-3317 complete kit, base 18-3417, all other parts the same as above.
If your vertical drive shaft has NO spring loaded little plunger on the top it has retro fitted with an Alpha lower...
Complete kit 18-3320, base 18-3420 all others the same.
If you have to replace the base use some NON hardening permatex on the o-ring that goes in to the drive on the bottom of the base. other than that no sealers are needed. Use some silicone spray on the impeller and rotate the shaft clockwise from the top while pressing down on the housing over the impeller.
If the plastic tube that goes on the water pump housing, the water tube used to help align the pick up tube in the drive is melted you will most likely need top and bottom housing.
Also don't go looking for MOST of the old impeller pieces, find the ALL or you may have problems. If you have power steering they are most likely in the heat exchanger found either across the back of the engine or down the port side.
It's a simple deal, but there are things you need to know to do it right.
Most kits come with a quad ring (small o-ring but square) that goes between the drives to seal the oil passage, replace it when ever possible to ensure good seal. I use a dab of Gask-a-cinch to glue it in place. The big square ring that goes on top of the water pump is there to prevent water from shooting up the shaft and washing out the spline grease from the top of the shaft as well as the o-ring on the top. Check for the o-ring if it does not come out with the drive or you will never get it back on.
If you do this on the boat with the drive raised (easiest) put the drive in forward gear as this is where the shift dogs will end up at this angle.
Then for spline alignment just turn the prop backwards a little as needed.