1976 Johnson 75hp water in cylinders

[craveman85]

My 1976 Johnson 75 HP 3 cylinder wasrunning ppoorly between idle and half throttle. Checked the carbs, ignition, compression... All good. Would push my 18' alumacraft 32 mph at full throttle. Went to start it again today and take it out after some carb link adjustments and it wouldn't start. Fuel and spark were good but wouldn't even fire. I pulled a plug to find a chocolate milkshake in the cylinders. Obviously water intrusion and a lot of it. I pulled the head and the gasket looks perfect. Held 110 top 108 mid and 108 lower compression. How much water can make it's way in from a faulty exhaust gasket? It looked like there was quite a bit in there and puddled up in the intake and exhaust ports. No water jacket cracks so I'm assuming that's my problem. Also any ideas on removing all the cover bolts without breaking them? I broke a few cylinder head cover bolts but they look easier to drill out

 

[craveman85]

Top cylinder Middle Bottom

 

[boobie]

Check the exhaust gaskets and plate.

 

[emdsapmgr]

Are you able to tighten any of the exhaust cover bolts? Sometimes the clamp load on the gasket loosen as the gasket ages.

 

[craveman85]

I'd like to replace them. Therefore no future problems probably put all new bolts in as well.

 

[craveman85]

And the amount of water it's spraying out the plug holes i doubt it's just loose bolts.

 

[Michael leblanc]

Had a mariner the same thing happen to me ill bet money it's your exhaust gaskets or the plate that is in the middle of both gaskets ...on mine it was the plate had a bunch of pin holes from rust and had to change gaskets cause they ripped when I I pulled front plate off

 

[Michael leblanc]

Had a mariner the same thing happen to me ill bet money it's your exhaust gaskets or the plate that is in the middle of both gaskets ...on mine it was the plate had a bunch of pin holes from rust and had to change gaskets cause they ripped when I I pulled front plate off.

 

[craveman85]

I was thinking of making my own gaskets from copper flashing or would aluminum flashing be better? I like making copper gaskets because you can anneal and reuse them.

 

[craveman85]

Just realized copper is a no go die to electrolysis. Picked up some aluminum sheet for the exhaust and new head gasket. I wanted to go a little thinner on the head gasket to bump compression without milling the head.

 

[F_R]

A too-common problem with the 3-cylinder loopers. The inner exhaust cover warps at the slightest hint of overheating, then the gasket leaks and squirts water into the exhaust ports. Usually spells doom for the powerhead unless you catch it quickly. Good luck with your metal gaskets. Let us know if it works.

http://s19.postimg.org/pjck39c37/3_C...AUST_PLATE.jpg

 

[craveman85]

Is there any fix if the cover is warped? Or would I need a new cover. The problem one is there piece after the first gasket from the block right?

 

[F_R]

Is there any fix if the cover is warped? Or would I need a new cover. The problem one is there piece after the first gasket from the block right?

Yes, block, gasket, problem cover plate, gasket, thick cover, etc. Well, see there is a problem. The "fix" is a new part. But they are unavailable. I suppose you could have a machine shop mill it flat, but that only makes the original problem worse. The whole thing started with bad engineering. The areas around the ports is very thin, and not supported on the back side. Mill it and it is even thinner.

 

[Bosunsmate]

you might find that the waters got into the inlet manifold area, ive had to drain that area before after an exhaust gasket leak.
put it back together but it kept on sneezing, the little hoses and valves for bypass covers can block up to if that motor has them causing poor idle/stuttering.
Dont dillydally too long as those bearings will rust up if kept wet with water ingress

 

[racerone]

No " bypass covers " on a 3 cylinder 1976 motor.

 

[craveman85]

Took the power head off to check my exhaust and found out the lower crank seal and bearings are shot. Somehow only 7 balls left in the bearing but it spins like a perfectly good bearing and I had no noise or anything coming from it. Still debating whether or not to bother pulling the exhaust housing.

 

[craveman85]

For now I threw it in a tote and spayed the crank case with the kero/oil mix I spray under my truck

 

[F_R]

My money says the water came from the exhaust cover, sprayed into the exhaust ports, and from there got into the crankcase, which destroyed that bearing from the inside. I'll bet you will find the damage is more extensive once you get into it. I've seen it way too often----including to my father-in-law's motor (twice). Running in the weeds of Lake Okechobee is what caused it, even though he watched for cooling stoppage like a hawk. As I said before, "the slightest hint of overheating"....

First time, Johnson replaced it under warranty. Second time, he trashed it and got something else.

 

[craveman85]

I think the bearing may have failed for the previous owner. It was pretty quiet and I'm sure I would ha e heard that. Cylinders and pistons all appear to be in good shape so maybe there's hope. Just trying to decide if its worth it for me or not. I'm still looking for a mercury 115 6 cylinder in great shape though.