92 Johnson 60hp bogs down and out after a mile

[hypeshipe]

I took the boat out yesterday and everything seemed to be fine until about a mile down the river. It started fluctuating in RPMs without throttle adjustment and then when I went to idle it shut off. When I got it started back up it sounded like I lost a cylinder. Lucky I found a sweet spot and putted home. I started pulling plug wires at the dock and this is what I found:

- Pulling the top plug made the motor run rough
- Pulling the center plug had no effect
- Pulling the bottom plug cut the motor off

I checked compression when I got home and had the following readings:

- Top = 108
- Center = 110
- Bottom = 101

I have fuel to each carb (even drips out of the front of the throat of each one), have compression and have spark. I am not getting any backfiring. With all of these factors I am at a loss for what the issue is. Could my timing be so bad that the motor would run but not misfire? Any help is appreciated.

 

[hall832]

Re: 92 Johnson 60hp bogs down and out after a mile

what do the plugs look like?

 

[hypeshipe]

Re: 92 Johnson 60hp bogs down and out after a mile

what do the plugs look like?

Top and bottom are black. Center had a white fluid on it.

I also switched the top and center plugs. It made no difference.

 

[hall832]

Re: 92 Johnson 60hp bogs down and out after a mile

Top and bottom are black. Center had a white fluid on it.

I also switched the top and center plugs. It made no difference.

the white fluid is water.

 

[hall832]

Re: 92 Johnson 60hp bogs down and out after a mile

Head gasket, exhaust gasket hopefully not the block. once you get a look inside let us know.

 

[hypeshipe]

Re: 92 Johnson 60hp bogs down and out after a mile

the white fluid is water.

That's what I was afraid of. How could I still have 110psi of compression with a gasket leak though?

I am going to start by pulling the exhaust cover and gasket. I am hoping that this is the problem due to the fact that I still have a good compression reading. If the exhaust cover gasket is bad I assume it could be letting water throught the cylinder wall exhaust hole when in the downstroke which would maintain my compression. Thoughts?

 

[cockedncupped]

Re: 92 Johnson 60hp bogs down and out after a mile

That's what I was afraid of. How could I still have 110psi of compression with a gasket leak though?

I am going to start by pulling the exhaust cover and gasket. I am hoping that this is the problem due to the fact that I still have a good compression reading. If the exhaust cover gasket is bad I assume it could be letting water throught the cylinder wall exhaust hole when in the downstroke which would maintain my compression. Thoughts?

I have not done it myself but I have heard that compression tests on these 3 cyl don't always tell you everything and a leak down is needed to determine if there is more than 15% variation in any cylinder...this might answer why compression still read well with a leak because you're typically only measuring maximum pressure rather than if there is a leak at any particular point in the stroke...

sorry not a ton of help but a partial answer...

 

[hypeshipe]

Re: 92 Johnson 60hp bogs down and out after a mile

Update: I pulled the exhaust cover last night and everything looks fine. I then went to pull the head and I broke the heads off of four bolts. Needless to say I am not very happy right now and I have a stuck head.

 

[EZSteury]

Re: 92 Johnson 60hp bogs down and out after a mile

Sorry to hear this, I can relate since this happened to Me recently. If it is only the heads see if You can pull the head off straight back, if not then You want to use maybe a diamond head bit and it around the head until it is small enough that You can pull the head back then You can use a torch to heat up the bolt (only) then once it is HOT You can turn it with some lock pliers, this is what I did on some of mine and it worked well for most of them.