2005 Merc XR6 150hp

[marlake]

Hi folks. I could use some help.
My XR6 started acting up toward the end of my recent Florida fishing vacation. Some mornings it just would not start. Now, I've owned this motor for 18 years and I've come to know its temperament but this was a new stubbornness. Some times I could get it to start after several tries and it would smoke so bad it was embarrassing. Once it cleared its throat it would run like a sewing machine. Stop to fish for a while and have to do it all again to get started.
Now that I'm home I've tried almost everything I am mechanically capable of to no avail. I saw a video of a guy with the exact same motor with the same issues and he fixed it by replacing the reed vavles. I did that and no improvement. I have spark, the fuel pump is good and the oil pump is good. Have new plugs gapped to spec. Fuel is fresh. Compression is 115 to 120 psi in all cylinders. I have tightened all hose connections to eliminate leaks and I intend to replace all hoses as soon as I can find a supply of suitable bulk hose.
I've been messing with this thing for a few days now and yesterday, while running on rabbit ears in the driveway, I noticed a slight water leak coming from the bottom of the head on the left side of the motor. Just a small drip every few seconds at this point but I bet it will get worse. Obviously this needs attention but I don't think this is linked to my starting/smoking problem. I'm hoping this is a simple gasket leak to the outside but maybe if the leak is entering cylinder/cylinders it may be the problem.
I'm gonna check timing this morning and then I'm all in.
I usually like to repair my boat, truck and motorcycle myself if I can. I'm at the point where I would put it in the shop but you all know that, now that the season is here, it would be weeks before any shop could help me.
I would appreciate any fresh ideas that you could provide.
Thanks in advance.

[Mike Cork]

Your definitely waist deep on this... Not much left, I didn't read anything about the power packs. If one of them is not firing it could cause the excess fuel/oil mixture in a cylinder that would be the excessive smoke after it does start.

While the gasket leak is probably a water jacket leaking externally like you said, depending on the gasket it could have leaks else where that are causing trouble. A parts break down diagram would help you with this.