Help with 1982 Johnson 15 HP - water in bottom cylinder

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Sinkingfast
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Help with 1982 Johnson 15 HP - idle issues

Post by Sinkingfast »

Pull the head and look...you probably will find the issue. Hopefully it will be the head gasket.
2 stroke every time I can
4 stroke only when I have to..I don't like boating with my lawn mower

CMOS
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Help with 1982 Johnson 15 HP - idle issues

Post by CMOS »

Sinkingfast wrote:Pull the head and look...you probably will find the issue. Hopefully it will be the head gasket.
It's a new Head gasket on there. Is this the primary way that water can get into the cylinder?


CMOS
1982 Johnson 15 HP - in pieces, in progress
Currently boatless :(

nccatfisher
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Help with 1982 Johnson 15 HP - idle issues

Post by nccatfisher »

CMOS wrote:
Sinkingfast wrote:Pull the head and look...you probably will find the issue. Hopefully it will be the head gasket.
It's a new Head gasket on there. Is this the primary way that water can get into the cylinder?


CMOS
That is the cheapest, they rest of the ways get more expensive as you go.

Sinkingfast
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Help with 1982 Johnson 15 HP - idle issues

Post by Sinkingfast »

I looked at my spare block and head..unless one or the other is bad..which is bad..its gotta be the gasket.

Now..look at the bolt pattern verses the gasket area. Those 2 center bolts have a lot more gasket to compress. Those heads warp high in the middle as many of us know. When I torque those bolts in the middle I use 18 ft-lbs and 14 on the outside ones as final setting. When I took off the head last year the head was flat..not high in the middle.

I betcha a nickle the gasket is leaking.
2 stroke every time I can
4 stroke only when I have to..I don't like boating with my lawn mower

CMOS
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Location: Magnolia, TX

Help with 1982 Johnson 15 HP - idle issues

Post by CMOS »

Sinkingfast wrote:I looked at my spare block and head..unless one or the other is bad..which is bad..its gotta be the gasket.

Now..look at the bolt pattern verses the gasket area. Those 2 center bolts have a lot more gasket to compress. Those heads warp high in the middle as many of us know. When I torque those bolts in the middle I use 18 ft-lbs and 14 on the outside ones as final setting. When I took off the head last year the head was flat..not high in the middle.

I betcha a nickle the gasket is leaking.

Quite possibly. Let me explain: when I pulled the Head to replace the T-stat (it was easier than removing the entire Power Head) the Power Head was still in the lower cowling. As such, when it came time to tighten the Head bolts I had poor access to the bottom 2 bolts, thus, I may not have tightened these to the proper spec. #-o

CMOS
1982 Johnson 15 HP - in pieces, in progress
Currently boatless :(

Sinkingfast
Posts: 231
Joined: 05 Oct 2014, 13:19
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Help with 1982 Johnson 15 HP - idle issues

Post by Sinkingfast »

Well..in a perfect world.. remember to torque those center ones a little more. Use a torque wrench on the ones you can and duplicate it on the bottom ones with a regular wrench the best you can.

My 76 manual says 12-14 ft-lbs. I have heard 20 also but my 76 says 12-14. 20 sounds better...

You can use a box end wrench with a hanging fish weight scale for a torque wrench. For a 10" wrench..go 12 divided by 10 times the recommended torque.
Last edited by Sinkingfast on 03 Jul 2017, 23:02, edited 1 time in total.
2 stroke every time I can
4 stroke only when I have to..I don't like boating with my lawn mower

CMOS
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Location: Magnolia, TX

Help with 1982 Johnson 15 HP - idle issues

Post by CMOS »

I'll see what I can do with those bolts without removing the Power Head (which I do no know how to do...).


CMOS
1982 Johnson 15 HP - in pieces, in progress
Currently boatless :(

CMOS
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Location: Magnolia, TX

Help with 1982 Johnson 15 HP - idle issues

Post by CMOS »

I tightened up the head bolts as best as I could with no positive results.

I guess it's time for the Head to come off again . . . .


CMOS
1982 Johnson 15 HP - in pieces, in progress
Currently boatless :(

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Pappy
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Help with 1982 Johnson 15 HP - idle issues

Post by Pappy »

Time to jump in here again.
It is time for you to pull the powerhead.
These heads do not warp by themselves. Nor do they warp due to any manufacturing defect. There is and never has been any need to stagger the torque of the fasteners to overcome any defect in the many many thousands of these engines produced and still running.
If warped, it was caused by heat.
If you have followed any of my threads on this engine you will know that it is a given that the grommets under the powerhead need to be changed.
Yours has all the tell tale signs of needing this done. Pulling the powerhead is a simple procedure. Fuel line, couple wires, shift linkage if yours is the old stye and around 6 fasteners. Once done you will laugh at how easy it is. Once off you can check the head and install a new gasket. Before pulling, I would check the compression and compare to any numbers you may have taken before.
Are you running in cold water with no thermostat? If so put the thermostat back in before you go this far.

CMOS
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Help with 1982 Johnson 15 HP - idle issues

Post by CMOS »

Pappy wrote:Time to jump in here again.
It is time for you to pull the powerhead.
These heads do not warp by themselves. Nor do they warp due to any manufacturing defect. There is and never has been any need to stagger the torque of the fasteners to overcome any defect in the many many thousands of these engines produced and still running.
If warped, it was caused by heat.
If you have followed any of my threads on this engine you will know that it is a given that the grommets under the powerhead need to be changed.
Yours has all the tell tale signs of needing this done. Pulling the powerhead is a simple procedure. Fuel line, couple wires, shift linkage if yours is the old stye and around 6 fasteners. Once done you will laugh at how easy it is. Once off you can check the head and install a new gasket. Before pulling, I would check the compression and compare to any numbers you may have taken before.
Are you running in cold water with no thermostat? If so put the thermostat back in before you go this far.
Thanks Pappy.

I have to admit I'm nervous about doing this myself, but right now it's a ~75 lb paper weight.

Are you referring to the "shift linkage" down where the lower unit connects?


CMOS
1982 Johnson 15 HP - in pieces, in progress
Currently boatless :(

timsmcm
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Help with 1982 Johnson 15 HP - idle issues

Post by timsmcm »

Do you have a factory service manual? If not get one.

CMOS
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Help with 1982 Johnson 15 HP - idle issues

Post by CMOS »

timsmcm wrote:Do you have a factory service manual? If not get one.

I do indeed.

One thing I have noticed about the service manual - it states in many places to "remove" this or "replace" that, but doesn't detail HOW to do so.


CMOS
1982 Johnson 15 HP - in pieces, in progress
Currently boatless :(

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Pappy
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Help with 1982 Johnson 15 HP - idle issues

Post by Pappy »

Brain Fart....meant Throttle linkage. Good time to clean and grease it all while the p'head is off as well.

CMOS
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Help with 1982 Johnson 15 HP - idle issues

Post by CMOS »

Pappy,

If I can get this thing apart - what am I looking for when I inspect?


CMOS
1982 Johnson 15 HP - in pieces, in progress
Currently boatless :(

Sinkingfast
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Help with 1982 Johnson 15 HP - water in bottom cylinder

Post by Sinkingfast »

Sometimes economics dictate technical decisions. I was not insinuating there was anything wrong with the head or the settings that have been in use for many years. 4 fasteners is the norm in higher performance motors in that area instead of 2. Granted I have only mic'ed 4 of these head gaskets and all were thicker in the middle. As long as the job gets done I guess 2 are fine. I don't see the issue with optimizing though..

When you pull the head the problem will be evident. For me surface finish is important at the gaskets fire ring area on the head and block. I betcha the leak is at the block..its harder to get clean and flat so forth. When I had my motor apart I ran the head interface of the block over a surface plate with body paper to flatten this area.
2 stroke every time I can
4 stroke only when I have to..I don't like boating with my lawn mower