1979 Johnson 70hp water in cylinder

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Skillz248

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I have installed new head gasket and exhaust manifold gaskets. The bottom cylinder is filling up with water. i can take out the plug and water pours out of it. Is there another gasket or seal that could be bad or does it sound like i got a hole in my block? great compression on all 3 cylinders. i have been thru my manual several times and I am stumped. Any help would be appreciated before i start the tear down.
 
Joe Reeves

Joe Reeves

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Re: 1979 Johnson 70hp water in cylinder

Did the engine at one time run okay, or is this a engine you just purchased and the problem already existed?

If it ran okay for you at one time and this problem just popped up..... did you do anything to the engine after which this problem took place?
 
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Skillz248

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Re: 1979 Johnson 70hp water in cylinder

i just bought the motor. the first time i fired it up it ran great until water started getting in cylinder and sputtered out. pulled plug and found water. the motor has definitely been hot as i can see all the melted tape and wrap around wires. put new water pump in during gasket changes. when the water pick-up tube goes in to bottom of engine is their any way that it could get in motor?
 
Joe Reeves

Joe Reeves

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Re: 1979 Johnson 70hp water in cylinder

The only way water could enter the powerhead as you state via the water tube would be if the tube was broken off at the top.... in which case it should have dropped off when you removed the lower unit. The water tube has a flange at the top of it and is seated within a groment in the adapter plate that the powerhead sits upon. I've never seen one break or come loose. It's impossible to remove without first removing the powerhead. Having an engine overheat to the extent you speak of, it's always possible that the base gasket of the powerhead failed.

Did you inspect the sealing surfaces of the cylinder head and block before installing the new head gasket?

Did you check the head with a straight edge for warping?

The head gasket should have been part number 313413. Was it?
 
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Skillz248

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Re: 1979 Johnson 70hp water in cylinder

Joe Reeves said:
The only way water could enter the powerhead as you state via the water tube would be if the tube was broken off at the top.... in which case it should have dropped off when you removed the lower unit. The water tube has a flange at the top of it and is seated within a groment in the adapter plate that the powerhead sits upon. I've never seen one break or come loose. It's impossible to remove without first removing the powerhead. Having an engine overheat to the extent you speak of, it's always possible that the base gasket of the powerhead failed.

Did you inspect the sealing surfaces of the cylinder head and block before installing the new head gasket?

Did you check the head with a straight edge for warping?

The head gasket should have been part number 313413. Was it?
Click to expand...


Yes i installed the correct head gasket and torqued to 20 ft lbs. i done the sand paper method on the head and there was no high spots. i did not change the water jacket gasket. could that be allowing water in? the pick up tube is firm and did not fall out. i kinda figured the powerhead gasket but went with the obvious route first. will continue with the tear down and hope its a gasket failure and not a water jacket problem
 
Joe Reeves

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Re: 1979 Johnson 70hp water in cylinder

I assume you torqued the head bolts to that specified 18 to 20 foot pounds in a ever widening circle such as follows:

9....10
5.....6
1.....2
4.....3
8.....7 etc, etc, continuing on circle wise. And if so, and the head isn't warped, that should have been fine.

Having water flow from the cylinder head water jacket area into the cylinder would necessitate a pretty good size crack in the top combustion area of the cylinder head.... unlikely problem. I've never encountered that.

Exactly what are the compression psi readings you're getting on all three individual cylinders?
 
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Skillz248

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Re: 1979 Johnson 70hp water in cylinder

Joe Reeves said:
I assume you torqued the head bolts to that specified 18 to 20 foot pounds in a ever widening circle such as follows:

9....10
5.....6
1.....2
4.....3
8.....7 etc, etc, continuing on circle wise. And if so, and the head isn't warped, that should have been fine.

Having water flow from the cylinder head water jacket area into the cylinder would necessitate a pretty good size crack in the top combustion area of the cylinder head.... unlikely problem. I've never encountered that.

Exactly what are the compression psi readings you're getting on all three individual cylinders?
Click to expand...

Yes Joe i torqued in the same sequence as in the manual. compression readings was all around the 95 psi range. dont remember exact but were within a few pounds of each other. i am gonna pull the exhaust back off and check them for any kind of warpage.
 
Joe Reeves

Joe Reeves

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Re: 1979 Johnson 70hp water in cylinder

That inner exhaust baffle plate is prone to warping, corrosion, cracks. Something I would never reuse when doing a rebuild. However, I've never seen one leak to the extent you describe.
 
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Skillz248

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Re: 1979 Johnson 70hp water in cylinder

I have not either Joe. maybe i missed something when i put it back together. just gonna have to pull the exhaust off of it and double check myself. It has to be in the exhaust side. I hope anyway
 
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durban

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Re: 1979 Johnson 70hp water in cylinder

Joe Reeves said:
That inner exhaust baffle plate is prone to warping, corrosion, cracks. Something I would never reuse when doing a rebuild. However, I've never seen one leak to the extent you describe.
Click to expand...

This is very true , i have found mine to be warped & fixed it with grinding paste & glass
 
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Skillz248

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Re: 1979 Johnson 70hp water in cylinder

Well i found the problem over he weekend. it was an error on my part. wrong middle gasket in exhaust manifold. replaced it and it ran on the muffs for an hour with no hiccups. new question? the relief valves were melted sometime long ago. are these necessary components? what do they do?
 
Joe Reeves

Joe Reeves

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Re: 1979 Johnson 70hp water in cylinder

Yes, without going into detail, the relief bypass valves and the thermostat at absolutely needed. Without them, proper cooling is impossible.
 
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