I have an old Formula 311 that has developed a leaky- or seeping -K-Plane reservoir. The fluid is seeping from the union between the pump and the plastic bottle (which is pretty loose- the bolt that holds it to the bottom of the pump is tight). Any thoughts (of the constructive repair variety) would be appreciated.

Take it appart and see if you have a bad O-ring between the pump and housing......that may be causeing the leak. If thats not the problem and maybe the plastic has warped i would probably try putting a few washers between the bolt and the housing to take the slack up.....or just buy a new housing

If your pumps are bolted to the transom like mine were that could be the problem. Most transoms are at a 11-13 degree angle. That is why my pumps were leaking. I tried replacing the O-ring and it did not work. I cut a 12 degree wedge out of wood and put it between the mount for the pump and the transom. No more leak.

The newer pumps and reservoirs are now attached with 4 screws from the top and shouldn't have a problem with the o-ring seal. They also come with a different cap to help stop leakage there. There is an in-between pump assembly that had the single bottom screw old reservoir, but the pump had the locations for the screws. If so, you can just get the newer reservoirs.

I will check out the new reservoir idea. The pumps are on the inside of the rear bulkhead / firewall. They are at a significant angle when the boat is in the water, so the fluid is always slopped up against the top of the reservoir.