2006 Johnson 30hp misfiring, water in bottom cylinder.

by John
(Gisborne, Australia)

I have had this boat only one week! Prior to purchase, I ran the engine pup with muffs attached. All seemed ok. When I first took it out, it would run well out of gear but once in gear, it would misfire badly under load. I took to an outboard mechanic and they have told me the bottom cylinder is getting water. When I asked where from, he said either from the shaft seal, the water galleries or the head. Could it just be the head gasket? The boat shop are trying to steer me toward a new motor!!

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Mar 16, 2014
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Three cylinder motor taking water in one cylinder
by: Bruce

Prior owner may have run through some Shallowater and possibly sucked up some Sand from the bottom and it may be plugging the water galleries in your head. If those water passages are plugged up you will see that when you take the head off. The head May have warped or crack depending on how hot it got.
Vacuum test the lower unit and see if it will hold a vacuum if it does not you may be pulling water in from the lake.

Nov 30, 2013
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your water in the cylinder
by: Anonymous

if you have a compression tester us it to see if the compression is close to the other cylinder or cylinder, they should be within 10 percent of each other, if that cylinder has low compression it could very well be a head gasket. If you can get the head off you should be able to see if the head gasket is leaking, or you may have a cracked head. A head gasket is not hard to replace, hope this helps a bit

Nov 25, 2013
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Water in cylinder
by: Anonymous

I would go get another opinion before purchasing another motor. Unless water has caused a lot of damage it should be rebuild-able.