Getting water in one cylinder, 200 HP Yamaha

milljo · #1 November 7th, 2004, 04:09 PM

It appears that water is getting into one cylinder of my 200 HP Yamaha ('96 model used in salt water) Even a new plug will foul after several hours of running. It is the top plug on the port side. All of the other plugs look OK.

I have had this boat for 9 months now. It worked fine until about 3 months ago when the plug started fouling. My inclination is to remove the head and see if I can find the source of the water. So my question is:

Any special considerations/techniques to removing the heads on a 200 HP Yamaha? It appears to be straight forward. Is there a particular sequence for removing (and replacing) the head bolts? Any assistance will be greatly appreciated.

rodbolt · #2 November 8th, 2004, 01:49 AM

hello

are you sure its water? water will clean a plug but not foul it. also if its saltwater and you carefully inspect the ground electrode you will see green flecks.are you positive its water? it can be a head gasket leak or a leak in the exhaust divider plate. the only trick is to carefully clean all gasket surfaces. do not use wire. I use the 3m pads on a drill. then use acetone or a carb cleaner that does not leave a film. rubbing alchohol will work. after cleaning its imperative to check the surface flatness of the head and the flatness and integrity of the aluminium around the cyl sleeves. other than that the torque sequnce and specs are on the head as well as your service manual.

good luck and keep posting

if its oil fouled check the plug caps and the recirc chek valve for that cyl. not all v yamahas used the check valve, a good way is to look in the parts diagram and see if they call that fitting on the block a nipple or a check valve.

good luck and keep posting

Ray Neudecker · #3 November 8th, 2004, 03:52 AM

The head bolts should be replaced in the sequence indicated on the heads and shown in the manual with proper torque. Note that the problem can also be caused by a carb problem if this is a carb motor,

milljo · #4 November 8th, 2004, 02:13 PM

Thanks for the info Rodbolt & Ray. I thought I have a water leak but now I'm not so sure. I don't mind removing the head & replacing the head gasket but I have never worked on an outboard engine of this type and am not sure of the potential problems. I have been reading a lot of posts about breaking off head bolts, etc. and would hate to get in a worse condition than I am. Does anyone have any tips/techniques for removing heads without busting bolts?

Ray Neudecker · #5 November 8th, 2004, 02:36 PM

First I would do a compression test to see if there is any reason to pull the head. If the plug is black and fouled. You are most likely working on the wrong end of the motor.

rodbolt · #6 November 9th, 2004, 01:42 AM

what ray says. try to post a pic of the plugs