Hi folks.
Last year I bought a sailboat project, that came with a 1961 Mercury 60 6hp outboard. The lower unit was separated from the main engine, and included a bag of spare parts, including 3 different sets of impellers. So it looked like someone was having issues. I managed to put it together with one of the impellers, and it ran reasonable. I noticed an occasional bit of oil leakage into the lake. Not nice. I used it for a week vacation then back at home, I checked the gear oil. Milky. So now I'm doing a bit of a deeper dive to see whats going on.
My motor has a little dowel pin into the driveshaft that drives the impeller. First impeller I used had a small slot on one end that engages with the dowel drive pin.
There was a lot of corrosion pitting on the shaft in the impeller area, which screws up the seals. One of the impellers had a smaller ID but was made for a longer key, so I put the shaft in my father's ancient Craftsman mini lathe and I turned down the raised areas of the shaft down to the main shaft diameter of 7/16" or 0.0438" that fits the other impeller fine, and leaves me with a clean seal surface, especially the lower water pump housing seal area. I found a NOS bearing (from my father's inventory) to replace the rusty bearing under the water pump. I replaced prop shaft seal and O ring, shifter seal, water pump O ring and lower and upper seals. I fabricated a pressure test adapter and the assembled lower unit held a 10psi pressure for 10 minutes and longer.
I tested the unit with a cordless drill in a bucket of water and it pumped a stream of water. Not a ton, but if I put my thumb on the output, it created a nice stream.
Time to test on the motor.
I ran the motor in a barrel of water, and the tell tail had a good stream of water at first, but then died out. Only steam coming out of the vent and exhaust. Probably overheated the engine, hopefully not totally ruined it.
I removed the lower unit and brought it in for a check. Lots of mucky oil in the lower unit exhaust area, and leaking out through prop exhaust area. Lower unit oil is nice and clean, not milky like previous tests. Not sure if level dropped. Top bearing was clean with fresh oil, but no sign of water. Back on pressure test rig, and it holds pressure fine.
I cobbled together a water feed from my garden hose to water feed tube to engine block, and ran the motor without the lower unit. With low water pressure/volume, there was a good constant supply of cool water coming out of the tell tale. Engine ran nice and cool.
So my question is?
1. What causes water flow to stop flowing to the power head? This motor doesn't have a thermostat that I know of.
2. Where does the mucky grease come from? Is it just a mix of exhaust fuel/oil residue and the cooling water?
In my early morning dreams and pondering, I was wondering about the seals of the intake water tube. So I made new rubber seals from some 5/16 fuel hose that tightly fits the two ends of the intake feed to the water pump. Can exhaust pressure in the lower unit reduce water feed to the water pump?
Appreciate any wisdom on this one.
Last year I bought a sailboat project, that came with a 1961 Mercury 60 6hp outboard. The lower unit was separated from the main engine, and included a bag of spare parts, including 3 different sets of impellers. So it looked like someone was having issues. I managed to put it together with one of the impellers, and it ran reasonable. I noticed an occasional bit of oil leakage into the lake. Not nice. I used it for a week vacation then back at home, I checked the gear oil. Milky. So now I'm doing a bit of a deeper dive to see whats going on.
My motor has a little dowel pin into the driveshaft that drives the impeller. First impeller I used had a small slot on one end that engages with the dowel drive pin.
There was a lot of corrosion pitting on the shaft in the impeller area, which screws up the seals. One of the impellers had a smaller ID but was made for a longer key, so I put the shaft in my father's ancient Craftsman mini lathe and I turned down the raised areas of the shaft down to the main shaft diameter of 7/16" or 0.0438" that fits the other impeller fine, and leaves me with a clean seal surface, especially the lower water pump housing seal area. I found a NOS bearing (from my father's inventory) to replace the rusty bearing under the water pump. I replaced prop shaft seal and O ring, shifter seal, water pump O ring and lower and upper seals. I fabricated a pressure test adapter and the assembled lower unit held a 10psi pressure for 10 minutes and longer.
I tested the unit with a cordless drill in a bucket of water and it pumped a stream of water. Not a ton, but if I put my thumb on the output, it created a nice stream.
Time to test on the motor.
I ran the motor in a barrel of water, and the tell tail had a good stream of water at first, but then died out. Only steam coming out of the vent and exhaust. Probably overheated the engine, hopefully not totally ruined it.
I removed the lower unit and brought it in for a check. Lots of mucky oil in the lower unit exhaust area, and leaking out through prop exhaust area. Lower unit oil is nice and clean, not milky like previous tests. Not sure if level dropped. Top bearing was clean with fresh oil, but no sign of water. Back on pressure test rig, and it holds pressure fine.
I cobbled together a water feed from my garden hose to water feed tube to engine block, and ran the motor without the lower unit. With low water pressure/volume, there was a good constant supply of cool water coming out of the tell tale. Engine ran nice and cool.
So my question is?
1. What causes water flow to stop flowing to the power head? This motor doesn't have a thermostat that I know of.
2. Where does the mucky grease come from? Is it just a mix of exhaust fuel/oil residue and the cooling water?
In my early morning dreams and pondering, I was wondering about the seals of the intake water tube. So I made new rubber seals from some 5/16 fuel hose that tightly fits the two ends of the intake feed to the water pump. Can exhaust pressure in the lower unit reduce water feed to the water pump?
Appreciate any wisdom on this one.
