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



## CMOS (Apr 3, 2017)

Howdy All,

I've been working on this "project motor" for the better part of a year. Every time I think I'm close, Murphy's Law kicks in, and kicks me in the you-know-what.

I won't go through the history other than to say I've done just about everything needed when buying a used motor that sat in someone's garage for years. Briefly: I had it running in the driveway last year when the recoil starter went to pot. Rebuilt it, then it failed again due to me NOT following the Service Manual instructions to the letter. I took a break for a few months because I was just worn out. 

Fast forward to this weekend. Rebuilt the recoil starter, re-cleaned the carb and checked the up and down float settings per the manual. I had it running like a champ today for about 10 minutes. I shut it off and started it about a dozen times. The pre-setting of the low speed mixture screw was perfect. Great idle.

After about 10-12 minutes all of the sudden the idle speed dropped so low that it would barely stay running unless I advanced the throttle a little. I did try to readjust the low speed screw but there was no improvement. 

On second thought some history would be appropriate: Great compression, Carb kit, rebuild fuel pump, rebuild starter, fuel filter, impeller, new fuel lines all around.

So, I don't get it. It seems like a carb problem. Any thoughts other than pulling the carb again (for about the 6th time)? Why would the idle speed suddenly change after running so well for the first 10-12 minutes?

Thoughts?

CMOS


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## CedarRiverScooter (Apr 3, 2017)

You might want to check the reeds too.


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## Sinkingfast (Apr 3, 2017)

An 82' with points...
The compression was in the history comment...has the comp changed since the event..
Does any load change things..
Did the throttle cam slip changing timing..depending on year cam arrangement..
What do the plugs look like...
And the obvious..did the motor drop a cylinder...
Is there gas spitting back into the air box..reed issue


I guess you are not supposed to have that motor..


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## CMOS (Apr 3, 2017)

My mistake mentioning the points - that was on my 1966.

I just tried a few things on the 82. I think I may have a fuel pump problem. I noted that the fuel filter showed no signs of fuel. Primed it again to fill the filter. Started up at low idle again but recovered completely within 15 seconds. Back to the smooth idle.

Another minute and the idle speed dropped again. Fuel filter looks empty. Re-primed and advanced the throttle, a short while later and I'm back to a good idle.

It seems like a fuel delivery issue, agreed? I did a rebuild of this fuel pump. It's possible I didn't do something exactly right. - ? I may need to buy a new fuel pump.

Sinking fast - I am supposed to have this motor. She's been one Hell of a teacher. I'll get her running. Wouldn't you?

Thoughts?

CMOS


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## Sinkingfast (Apr 3, 2017)

I don't like the oem pump so I use a Mikuni rectangle pump on my 15. No springs on the check valves to raise the head. I also pull the springs out of the primer bulb. They add head to the system. Try raising the tank above the motor if you can..you might find an air leak by looking for the wet spot. 

It does sound like a pump that doesn't like to pump at low pulses. Or an air leak. 

Had exact issues with my 76'..which is now a 76'..81'...87'...and 91' all in one motor.


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## CMOS (Apr 3, 2017)

Good points. I'm also going to do the next test in a barrel instead of the muffs - just to be sure of the water pump capability (new impeller and T-stat).


CMOS


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## Pappy (Apr 5, 2017)

Leave the pump as is. Leave the primer bulb as is. 
They have both been working on millions of engines without "modification" for over a half century. 

If you want to see if your pump is leaking, pull the pump off the side of the engine and pump up the primer bulb. If a diaphragm is leaking you will see fuel present at the air port on the pump. Pretty simple? 
Secondly. You have to remember that the inline filter you are watching is on the SUCTION side of the pump so it will naturally pull any excess fuel from the filter element and the element will look almost empty. That is normal as well. 
For your "test" you were doing two things at once. Pumping the primer bulb and giving the engine some throttle. Do one or the other, not both. 
Giving the engine throttle will clear the crankcase of excess fuel and raise your idle and clean it up every time. Make a small adjustment to your mixture and repeat. Champion plugs run best in that engine by the way. Setting your mixture on the hose is only a temporary setting anyway but have fun and learn.
Is your engine warming up to around 130f at idle? Makes a big difference in mixture setting and prolonged idle ability.


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## CMOS (Apr 5, 2017)

Thanks Pappy.

Yes, the motor is keeping a good consistent head temperature. I was regularly placing my hand on the top of the head for easily 10 seconds.

With regards to your comments about advancing the throttle: When the idle dropped low I would re-prime the fuel line while advancing the throttle just enough to keep her running. After several seconds I could hear the RPM's increase a bit at which time would back off the throttle to IDLE, and observed the smooth idle. After a few minutes the low idle would return. Rinse and repeat...

When the idle was operating normally, the mixture screw is set right where it needs to be per the standard adjustment technique (small adjustment, wait...).

So other than fuel availability, I'm not sure what would cause the intermittent low idle. I am using Champion plugs.

I will pull the fuel pump and look for leaks. And I will try the next test by ONLY using the primer bulb, not advancing the throttle. I'm so close to getting this baby running.

CMOS


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## Tinny Fleet (Apr 11, 2017)

One tip I learned a few years ago is to install a clear or see-through line between the fuel pump and the carburetor. That way you can quickly check your fuel flow at the last point before it enters the carburetor. The hose is available at the big box hardware stores.


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## CMOS (Apr 11, 2017)

SmallmouthFool said:


> One tip I learned a few years ago is to install a clear or see-through line between the fuel pump and the carburetor. That way you can quickly check your fuel flow at the last point before it enters the carburetor. The hose is available at the big box hardware stores.



Good point. I did that on my 1966 9.5. Used the semi-clear Tygon tubing. I'll probably do the same this weekend to the 15 when I have some time to do some more testing.


CMOS


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## CMOS (Apr 15, 2017)

Update 4-15-17:

I did a test by placing the fuel tank above the motor itself (on top of my pickup toolbox), and the water supply was a barrel (no muffs). As before I was able to get her started at normal idle. I just left it in the driveway and sat down and watched. After about 4 minutes it died. 

Started it right backup, but at low idle again.

Gave it some throttle and after a few seconds I could hear the RPM jump. Back off throttle, back to normal idle. After less than a minute, back to low idle and died.

I was able to repeat this same thing for over 30 minutes. It will idle fine for short period of time, then low, rough idle.

I did find a small air leak in the hose fitting going into the fuel pump. Tightened it up. Still the same symptoms.

I also checked the fuel pump metal screen filter. Super clean.

When it does idle at normal RPM's it's as smooth as glass, but it doesn't last long.

Question: when operating with the muffs, where should I see water OUTPUT other than the pee hole? I'm not seeing any water exit the engine other than the pee hole. Related?

Thoughts?


CMOS


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## Weldorthemagnificent (Apr 15, 2017)

Check to see if there is a oil return line on that model. If there is it will come from the shifter side of the motor to down low under the carb on the front. This line draws oil/fuel up from pooling by the lower bearing and back into the head. If the line is old and hard, or cracked, it might be periodically sipping air causing a lean condition at idle and it won't help fuel pump impulse either. I had a motor with this problem and had just about pulled out all my hair before I found it. 



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## CMOS (Apr 15, 2017)

No oil return line.


CMOS


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## Weldorthemagnificent (Apr 15, 2017)

Does it time ok everywhere except idle? Two places I would look first to eliminate. One the carb, the idle circuit holes are teensy and can look clean but have a bit of crud in them. Also assuming fresh good fuel. 
Second do a leak down test to check crank seals. This will have to be done by a mechanic with a tester. 


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## CMOS (Jul 2, 2017)

Update 7-2-17:

I had some time to fiddle this weekend and what I found doesn't sound good:

I replaced the fuel pump and found no difference in the symtoms: starts and runs fine then idle gets low and very rough, then dies.

I pulled the plugs right after the symptoms showed. Top is fine, bottom plug is fouled with WATER. 

I repeated the test after I cleaned both spark plugs, and got the same results: starts and runs fine, then 2-3 minutes later the idle drops and then motor dies. Bottom plug fouled with water.

Please help. How the heck can this happen?

CMOS


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## Sinkingfast (Jul 2, 2017)

Pull the head and look...you probably will find the issue. Hopefully it will be the head gasket.


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## CMOS (Jul 2, 2017)

Sinkingfast said:


> 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


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## nccatfisher (Jul 2, 2017)

CMOS said:


> Sinkingfast said:
> 
> 
> > Pull the head and look...you probably will find the issue. Hopefully it will be the head gasket.
> ...


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


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## Sinkingfast (Jul 2, 2017)

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.


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## CMOS (Jul 2, 2017)

Sinkingfast said:


> 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


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## Sinkingfast (Jul 2, 2017)

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.


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## CMOS (Jul 3, 2017)

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


CMOS


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## CMOS (Jul 5, 2017)

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


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## Pappy (Jul 5, 2017)

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.


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## CMOS (Jul 5, 2017)

Pappy said:


> 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.
> ...



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


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## timsmcm (Jul 5, 2017)

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


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## CMOS (Jul 5, 2017)

timsmcm said:


> 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


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## Pappy (Jul 5, 2017)

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


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## CMOS (Jul 7, 2017)

Pappy,

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


CMOS


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## Sinkingfast (Jul 7, 2017)

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.


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## Pappy (Jul 7, 2017)

First, to give you peace of mind. 
Will be a bit more specific on powerhead removal. 
There are 6 retaining bolts at the bottom that need to be removed.
Remove the air silencer and choke knob from the carburetor.
Remove the rewind starter. You will need a 3/8-16 nut handy. Unscrew the one bolt and be careful not to allow the spring to come out. Watch the lower cup.....
Tie a loop in the starter rope (pull some out). Once removed put the 3/8-16 nut on the bottom of the bolt to retain the starter assy.
Remove the 3 pan mount nuts. Remove the upper two washers (large and small).
Remove the fuel line from the fuel pump. Replace when the powerhead is off...freshen it up!
Remove any ground wiring from the stop switch and the black/yellow as well. 
You will see the throttle gearing. This should come up by itself. Note the position for re-assembly. Clean and lube everything while you have the p'head off.


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## CMOS (Jul 7, 2017)

Thanks Pappy.

I've done a carb kit and rebuilt the recoil starter twice (this is what happens when I didn't follow the Service manual instructions...) so taking these things off are easy for me.

However - what are the "3 pan mount nuts"?


CMOS




Pappy said:


> First, to give you peace of mind.
> Will be a bit more specific on powerhead removal.
> There are 6 retaining bolts at the bottom that need to be removed.
> Remove the air silencer and choke knob from the carburetor.
> ...


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## Pappy (Jul 8, 2017)

If you remember from removing the starter........
Below the starter is the one forward pan mount. The powerhead actually supports the lower motor pan. You will see the forward one in this location. At the rear on either side are the other two. 
There is a bushing that loves to fall out of the center of the rubber mount......be aware as Murphy will carry these to remote locations, never to be found again. 
Nice thing about the way this engine was designed is that the pan can now be removed and thoroughly cleaned. The mid-section is now light and can be thoroughly cleaned, all the throttle linkage and gears can be removed, cleaned and lubricated, fuel lines replaced, etc. 
When you get done you will have an engine that has now been properly serviced and will or should need nothing for quite a while.


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## CMOS (Jul 8, 2017)

Pappy,

"When you get done you will have an engine that has now been properly serviced and will or should need nothing for quite a while."


From your mouth to God's ears.


CMOS :mrgreen:


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