Johnson 115HP Head Gasket problem

Discussion in 'Boats and Motors' started by PondFin@ic, Mar 21, 2008.

  1. Last summer I blew a head gasket on a used boat I recently purchased. The previous owner said the motor had been recently rebuilt. When we removed the blown gasket we found that an area just outside the cylinder sleeve about 1/4" deep and 1/2" wide of the aluminum was eroded. The cylinder sleeve did not appear damaged but it looked like the hot gasses that leaked past the gasket had just eaten away the aluminum surrounding the sleeve. We were in the middle of nowhere so we just installed a new gasket and the compression was fine. I finished out the week of fishing and the boat was only out twice more last year.

    Is this something that should/can be repaired? Or should I just keep a spare head gasket handy?
  2. TMK


    If it's holding, don't mess with it!

    The seal around the cylinders is formed by compressing the metal ring between the head and top of the cylinder. So, the area with missing metal shouldn't cause problems.

    If it goes and starts steaming, shut it down ASAP you can score the cylinder walls in no time.

    Keep a spare gasket on hand. If it does go again, Be careful to follow the tightening sequence with NEW bolts and use a good torque wrench. Don't even bother with the $29.99 one from Harbor Freight. Check your cylinder head for warpage also.

    As long as your not blocking off a water passage, an option might be filling the void with an epoxy like J.B Weld and finishing it flat and smooth. Never tried the stuff myself, but I've heard of similar repairs being done.

  3. Thanks for your input. I have a $300 torque wrench but I don't have the torque or tightening sequence specs. Anybody know them or have a link to them for a 1998 Johnson 115hp.