NEED HELP 1977 70hp johnson

[Fowl_obsession]

WHAT I HAVE: 1977 70hp 3cyl johnson and parts motor that the old owner said had bad compression.

MY PROBLEM: I got the motor running about two weeks ago, everything was going smooth. Last week i went to warm it up before i checked compression. It bogged down and acted like it was flooded so i took the plugs out and cranked it. Lots of water sprayed out. I took off the lower unit and the head. When in the lower unit, i found a small washer just sitting there on top of my water pump housing like it had been just floating around.when i took the head off, the gasket looked fine, my bottom cylinder had been beaten to heck. A bunch of noches in it (could have been the washer?) My pistons have "0.03" engraved on them.

What are my options?

 

[racerone]

The motor has already been rebuilt with 0.030" O/S pistons.-----With bad compression it needs to come apart again.---I doubt the washer caused the problems.

 

[Fowl_obsession]

The motor has already been rebuilt with 0.030" O/S pistons.-----With bad compression it needs to come apart again.---I doubt the washer caused the problems.

Im not sure if my motor had bad compression, my parts motor did. Could i go back to .03?

 

[emdsapmgr]

The dents in the piston are from pcs of the top ring which failed. The top ring breaks into pcs, and the pcs get wedged between the piston crown and the head face. Piston is scrap. Lower cyl probably has little compression. Head may/may not be useable. You may be able to get a factory replacement .030 piston and put that in, as long as the cyl walls still look ok. Before you put any $ into that powerhead, you need to know why the bottom piston failed. Bad overbore, wrong size piston, lack of lubrication, etc.

 

[Fowl_obsession]

The dents in the piston are from pcs of the top ring which failed. The top ring breaks into pcs, and the pcs get wedged between the piston crown and the head face. Piston is scrap. Lower cyl probably has little compression. Head may/may not be useable. You may be able to get a factory replacement .030 piston and put that in, as long as the cyl walls still look ok. Before you put any $ into that powerhead, you need to know why the bottom piston failed. Bad overbore, wrong size piston, lack of lubrication, etc.

What should i look for when taking it apart, and would the failed rings cause the water in my cylinders?

 

[racerone]

Failed piston ring will not cause water in the cylinders !!---Since this motor has been apart before there is no telling what was done and what the failure was.---Possible that water got in from a number of places.-----Crack in exhaust manifold.---Leaking gaskets on exhaust covers.---Bad lower seal.

 

[Chinewalker]

Water could be the root cause of the failed piston. Tear apart both motors, use the best of what you've got, if compatible.

 

[Fowl_obsession]

Water could be the root cause of the failed piston. Tear apart both motors, use the best of what you've got, if compatible.

I dont know why the parts motor had bad compression, should i go ahead and plan on having that block bored out and using it since i cant bore out mine any more?

 

[jakedaawg]

Yours may be able to be re-sleeved. The issue is the water. If it came from the exhaust there is a chance that those parts are no longer available. Also there is the cost. You most likely can find a used triple that runs for less than the parts and machining even if you don't count your time.

 

[emdsapmgr]

The .030 sleeve may not need overboring. If the boring to .030 over was just a few run hours ago, it's possible the sleeve is re-useable with just a light hone. You'll know more when you get it apart. The water intrusion issue brought up in post #6 by racer may be repairable. It's a separate issue-part of the exhaust system. Some parts, like the exhaust manifold, may be warped. Possible the clamp load on the manifolds was not to spec. Anyway, these water leak issues may well be repairable. Since you've got two powerheads, you may be able to put together enough exhaust parts for one good powerhead. Ditto for the rotating assembly (crank, rods and pistons.) Before you continue speculating on repairs, parts needed: get the block torn down and inspected.