rifleman_maynard
Seaman Apprentice
- Joined
- Oct 11, 2006
- Messages
- 33
I started the outboard for the first time this AM. I had it on the muffs, running 50:1 premix and sea foam(until I can go through the oiling sysem) with the sub (inboard) oil tank disconnected as it has a epoxy/glass patch setting up right now.
I had sprayed the sparkplug holes with sea foam a couple of weeks ago, so when it started after about 10 seconds of cranking it smoked quite a bit. As it warmed up and ran for a few minutes this improved.
The engine ran a bit rough as I expected it might given the Yamaha shop's report of a low compression cylinder. After a minute or so though it smoothed out a lot. I looked it over carefully while it was running for leaks/smoke/whatnot. There were a few droplets of water appearing at the line of the head gasket on the right side between the upper and lower cylinders. When the heads felt warm to the touch, I killed it, removed the plugs and checked the compression.
Starting at the bottom portside cylinder going clockwise: 102, 102, 98, 60psi. The spark plug in the low cylinder was interesting. All the plugs were dark not black and a bit wet with oil or fuel. The plug from the low cylinder was a little lighter over all but on the side toward the area where the water leak was, the insulator was much lighter from about 2 o'clock to about 5 o'clock.
So, I have a leaky head gasket. I need to pull the head, inspect for corrosion and flatness, replace the gasket (with OMC sealer per rodbolt's post on the subject?) and retorque everything to spec.
Is there anything else I need to look at while I am in there? Cylinder walls and piston tops of course.
Thanks for any help!
I had sprayed the sparkplug holes with sea foam a couple of weeks ago, so when it started after about 10 seconds of cranking it smoked quite a bit. As it warmed up and ran for a few minutes this improved.
The engine ran a bit rough as I expected it might given the Yamaha shop's report of a low compression cylinder. After a minute or so though it smoothed out a lot. I looked it over carefully while it was running for leaks/smoke/whatnot. There were a few droplets of water appearing at the line of the head gasket on the right side between the upper and lower cylinders. When the heads felt warm to the touch, I killed it, removed the plugs and checked the compression.
Starting at the bottom portside cylinder going clockwise: 102, 102, 98, 60psi. The spark plug in the low cylinder was interesting. All the plugs were dark not black and a bit wet with oil or fuel. The plug from the low cylinder was a little lighter over all but on the side toward the area where the water leak was, the insulator was much lighter from about 2 o'clock to about 5 o'clock.
So, I have a leaky head gasket. I need to pull the head, inspect for corrosion and flatness, replace the gasket (with OMC sealer per rodbolt's post on the subject?) and retorque everything to spec.
Is there anything else I need to look at while I am in there? Cylinder walls and piston tops of course.
Thanks for any help!