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70hp Johnson FOOT REMOVAL

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GaryOutland

Contributing Member
The 1981 70 HP Johnson runs great! Ran it in tank . Forward and reverse. I noticed water coming out where the foot meets the "midsection". Water in oil. I pulled 5 bolts out . The foot is not coming out. How big of a hammer should I use to get it off. KIMG0263.jpg
 
OK I will. Just stopped to eat dinner, and thought I would post this just in case. Would water as you see in pix necessarily a bad thing, say,vmore than a bad gasket typically, if any thing is typical.
 
Bolt under the trim tab. make a scribe mark on the tab into the unit so that you can reinstall it exactly where it was.
 
Put the bolts back in. Water coming out there is normal and harmless. In fact, it is supposed to drain out the drain holes. The oil is the oil that you put in the gas, has gone through the engine and done it's job, and is discharged out the exhaust--with the cooling water that has done its job. All perfectly normal
 
Fdrgator,
The water in oil means that when I took out the drain and fill screws for gear oi in foot, water came out. It was not milky. Just water. I am assuming that there was little or no gear oil in it when I tested engine.
 
Oops, I guess I didn't read that very well. I didn't realize you meant there is water in the gearcase. That's a whole different matter, and now I understand why you are tearing it down. My comments about the water coming out the drain holes remain. But that is not the reason for water in the gearcase. Two separate issues here. One normal and one dead serious.
 
I have the foot off . Feels good so far.
Question 1. What does the trim tab do and why is it critical to put it back in same position?

Question 2.Can water get into gear case thru water pump.where else?I believe that The water that was in gearcase is from me putting the motor in test tank, to crank engine. Three of the four bolts on outer edge of foot were completely missing. Gear oil anfd water was not mixed
 
The trim tab adjusts the engine to compensate for the engine's torque. It requires moving it about 1/8" at a time in order to get the boat to travel in a straight line. Moving away from the setting will have the boat automatically turning in one direction or the other with the operator fighting it 100% of the time.

Water can enter the gearcase through a damaged seal under the water pump, the "O" Ring that seals the shift rod, or the seals and/or "O" Rings at the propshaft carrier housing.
 
Thanks Joe. I pulled water pump and see what you and the manual say. I know that asking a knowledgeable mechanic can offer more insight than just reading a book. It appears that someone tried to use silicone caulk around water pump plate. I will replace o-rings now.

My wife said that I better have a boat in water by the 4th, so she can go fishing this week. I still have 11 hours and 40 minutes.
 
Silicone (ugh!)

The best sealer to use between the pump impeller plate and the lower unit is as follows... also the best to use on the goofy looking "O" Ring between the impeller housing and the plate... makes an excellent seal.

OMC Adhesive is now Bombardier 3M Product #847 and may be listed as Scotchgrip 847, part number 776964
 
Before you go any further have the gear case pressure and vacuum checked. That way you'll know exactly where it's leaking.
 
I don't have pressure tester yet. I didn't have time to rig one up. I am ordering gearcase seal kit today, along with water pump kit.
To test it i filled gear case with hydraulic fluid and let it sit for a few minutes. right side up, no leaks from prop seal. Laying on side, oil came out of drive shaft under water pump, and shifter housing. I put gasket material liquid under shifter housing and it stopped the leak there.
Just for "fun", i ran it in gear for a minute to see how the oil would look. it was milky that quick.
 
The throttle doesn't want to drop to idle speed after revving. The shaft that the throttle linkage and timing advance arm pivots on has a teflon bushing. this bushing looks to be in great condition, but the assembly , in my opinion, is too tight. should it be lubed? I did disconnect throttle cable and linkage to carbs to pinpoint the problem. The spring for the advance seems to be perfect. As you know, it only takes 1/32" from the low idle stop to be revving pretty high in neutral. When I use the throttle lever for high idle to start engine, it goes back to low idle very slowly. It is not in the throttle cable. Any thoughts?
 
I wouldn't use that 3 vane impeller. Didn't know they were still out there. Get a 6 vane one as the 3 vanes had problems.
 
NEW ISSUE! Put boat in water today. Idles through ycanal just fine. Applied throttle when I got to open water.ran good but would not plane. Shut engine off. Adjusted angle of motor. Restarted engine. It would idle ,but would not increase rpm in gear. It felt like a dead spot. If I bumped the choke breifly, engine rpm would increase . Limped back to ramp and loaded on trailer. When I got home I realized that the 3 gallon tank with 2,75 gallons was sealed. I did not open vent. Could this lack of ventilation cause this issue?
 
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