Tigershark 1998 770L - Milky substance in one cylinder

[cobalt190]

Took my son out yesterday and was trying to get him up on one ski, but the Tigershark 770 would not run over 30 mph full throttle (normally the ski will hit 51-54 mph). So went to put new set of plugs in and rear cylinder showed signs of milky fluid on the plug when I pulled it. Looks like I have a bad head gasket allowing water in the cylinder or maybe a warped head or both or any other ideas? I tried to see if there was spark by observing the plugs when turning over, but I must not have had a good ground becase I could not see a flash (I was in the boat house in the shade). Any suggestions for testing for spark - that is safe? So any suggestions before I pull the head and order a new gasket? Cobalt190 - that is my other boat! 10 years old and 230 hours garage kept/covered - looks new! (wabeckii@gmail.com). By the way - even with one cylinder, my 11 year old was up on one ski and took 5 times around the lake.

[Technical Support]

Re: Tigershark 1998 770L - Milky substance in one cylinder

Buy a set of spark testers to go in between the wires and the spark plugs, these work well when looking for good spark.

[cobalt190]

Re: Tigershark 1998 770L - Milky substance in one cylinder

Ok I have spark, so took head off and got a two new ones off e-bay and a couple of new head gaskets (from SBT). Installed and tried to fire up the ski - could see milky substance (water) coming up the plug hole. So I figured I had a bad head gasket! Getting the water pulled up from the crank case was a real chore with a siphon and working it down the cylinder ports. Replaced gasket this evening and without water on - fired up the ski and ran it for a few seconds. So far so good. I just wonder if I have a blown cooling jacket on the cylinder wall or if the head gasket is not sealing properly (I following the recommended 3 step torque pattern and going up to 20 ft-lb with a sweep dial torque wrench). I dont want to put water hose on the ski with any pressure at this point. I have two options as I see it - put it in the water on the weekend and see what happens (risk filling the crank case with water again) or swap out the head now and put on my new spare gasket. Any thoughts or recommendations? If all goes bad, I'm considering the standard rebuilt engine that SBT offers for $750 a set of install gaskets and a new impeller. Historically I have had a head get hot and bust a head gasket, had two starters fail and a bendix on the ski, so have had it down for repairs about once a year.