1984 Johnson Outboard 70HP

[Fudoshin]

Hey everyone I bought a 1990 Bayliner capri it came with a1984/ 70HP Johnson, the only thing is the motor has an issue. The previous owner was out with his kids tubing and the motor blew a small hole. It looks like the cooling jacket could be cracked. The previous owner said that the motor still runs but overheats quickly, and there is no water coming through the pee-hole. I am guessing the water pump was bad and he didn't see it while running the motor and thats why the hole blew. Can I get by with patching the hole and replacing the water pump? Any advice will be greatly appreciated. I bought the boat, w/ trailer fish finder, battery, fuel can, for only $300.00 the guy was a rich dude and didn't want to stick money into it.

ATTACHED IS A PICTURE OF THE HOLE THE GUY PUT JD WELD OVER IT, IS THERE SOMETHING BETTER TO PATCH THE HOLE WITH?

MOTOR SERIAL AND MODEL NUMBER

MODEL: J7OTLCRD
SERIAL: J5981552

 

[Pappy]

Hate to tell you but there is no cooling in that area. Looks like a rod came through to me. Take compression and see. This is based on what looks like the JB Welded area. Unless someone already went through and repaired the damage internally you may not have such a good deal.
The cooling starts on that engine right about where that tall rectangular exhaust plate is and rearward from there. Anything in front of that is induction and the rounded areas are where the big end of the rods rotate around the crank. That looks like the JB area to me on #3 cylinder.

 

[Fudoshin]

I'm not too savy on outboards, I just started getting into this field a year ago with boats and what not. So the JD area is where the #3 cylinder is? If a rod shot through would patching it be a temporary fix or will I have to have it taken apart and get new parts? It definitely got too hot and that's why the rod shot through. How do I check for compression?

 

[Pappy]

Go to an auto parts store or Sears, etc. and buy a cheap compression gauge. Remove the spark plugs and re route the plug wires away from the spark plug holes. Thread in the gauge in each hole and engage the starter until the gauge reads the highest number. No need to do anything with the throttle. Record your numbers and let us know.
JB weld is a very temporary fix..........enough to get it sold apparently.
Keep in mind that the hole in the block is nowhere near as important to fix as what created the hole in the first place. If it was an overheat then that piston "stuck" hard enough to fail the connecting rod............. Huge repair.