Milky plug

[seagoo]

I have a 1995 225 Mariner Magnum EFI 3.0(I can get serial # if needed, but boat is current shrink wrapped). It has 300 heads, cut can, and 4 hole intake. Other than that it has never been touched except for routine maintenance since 97 when most mods were done.

When I went to winterize it, the mid plug on the left side of the engine was milky. Cylinder 3 or 4? The cylinder was not wet with water, and I spun the motor over with the plug out. So I added some premium plus to the cylinder a spun the motor over a couple times to make sure it was lubed well. I did the same for all the other cylinders as well when I winterized it. All other plugs looked good.

I first suspected the o-ring on the head and plan to replace them, but further research I found it may be the exhaust divider plate, or the base gasket. Any ideas?

Last time I ran the boat on the lake it wasn't missing or anything, but I did notice at idle, some water was spitting out of the above water exhaust relief. The motor had never done that before, but I just replaced the water pump and chalked it up to extra pressure at idle. I don't have any water pressure issues or have in the past, 5-6 psi idle and 12-15 at WOT.

So am I on the right track? Should I replace all o-rings and gaskets, or just start tearing down to find the reason? I have a factory service manual and am comfortable and mechanically inclined enough to do the job, just looking for any extra input before I begin.

Thank you for any advice. (Sorry for the book)

Matt

[EuropeanAM]

I don't believe you're going to find a divider plate on your 3 liter engine....

Base gasket isn't impossible.... but it's unlikely (would more likely affect a lower cylinder also). However, you're going to need to locate the "source" of the water leak. Don't forget to check the idle relief BOOT for cracks or splits.

More than likely, you'll find the problem at the cylinder head o-rings. Suggest addressing this BEFORE running the engine!

If you need o-ring kits, we probably have them in stock.

[seagoo]

Thank you Don. I will pull the head and check the o-rings first. I will be calling you for parts soon. Thank you for all your help and knowledge.

[seagoo]

I pulled the heads and found hard, deteriorated o-rings. All cylinders looked great. I called this morning and orderd parts. Pay pal sent. Thank you Don.

Matt