1986 150 evinrude number six plug has sludge on the plug

Noticed reduced power from the outboard its a v6 so i put new plugs in and ran all day it pulled the plugs and i see a yellow white sludge on the number six plug not a lot but around the cavity in the plug. I still think there is no fire on the cylinder i am assuming that water has made its way into the cylinder some how. or maybe fuel in the line i did change the water seperator can any one please help. All the other plugs look great.

Re: 1986 150 evinrude number six plug has sludge on the plug

check compression on all cyls. sounds like a head gasket issue.

Re: 1986 150 evinrude number six plug has sludge on the plug

If you are lucky, it's a bad/leaky head gasket. Easy fix. If the head gasket is ok, they you may have a water leak in the exhaust chest. Usually exhaust water leaks affect the lower cyls first. That is also not a difficult repair on this flatback engine.

Re: 1986 150 evinrude number six plug has sludge on the plug

Hopefully just a head gasket. Compression check to start the ball rolling is a wise idea. Photo of the plug would be a good visual for us to diagnose as well.

Re: 1986 150 evinrude number six plug has sludge on the plug

I talked to a mechanic friend and he said that that block had problems due to inferor metals and its the cylinder block that has the leak and the metal is old and he is 99% sure the engine is toast. The amount of sludge is the size of half of an pencil eraser and it seemed to be packed around the orfice of the plug not on top of the hook. I would think it is a small amount but its enough to keep it from fire. it looked like cream light colored i kept the plug out but the sludge is gone now. I hope the engine is not toast it runs about 35mph with out the fire of #6 . Tomorow i will pull the head cover and then remove the head what should look for. my friend never looked at it he is assuming. And can i do with out the #6 till i can find a new outboard.

Re: 1986 150 evinrude number six plug has sludge on the plug

spankydoo said:

I talked to a mechanic friend and he said that that block had problems due to inferor metals and its the cylinder block that has the leak and the metal is old and he is 99% sure the engine is toast. The amount of sludge is the size of half of an pencil eraser and it seemed to be packed around the orfice of the plug not on top of the hook. I would think it is a small amount but its enough to keep it from fire. it looked like cream light colored i kept the plug out but the sludge is gone now. I hope the engine is not toast it runs about 35mph with out the fire of #6 . Tomorow i will pull the head cover and then remove the head what should look for. my friend never looked at it he is assuming. And can i do with out the #6 till i can find a new outboard.

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never assume, and a "mechanic friend" can be your worst enemy when he passes on unknowns. jmo

Re: 1986 150 evinrude number six plug has sludge on the plug

I will pull the cover and take pics the head cover and the head? I will need to buy a compression tool first its not full of sludge just a little.

Re: 1986 150 evinrude number six plug has sludge on the plug

Diagnose as soon as possible. Compression before pulling anything off.
Dump the helpful mechanic at this stage !!!!
Long range diagnosis of "inferior metals" he is either a genius or at the other end of the brain scale.
I know what my thoughts are.

Re: 1986 150 evinrude number six plug has sludge on the plug

Sounds like either a head gasket or exhaust cover leak.

Re: 1986 150 evinrude number six plug has sludge on the plug

Head gasket blown thanks for the help while replacing the head gasket i found that the head bolt on the bottom side of the head has a broken off bolt in the block when i installed the new gasket i put it back together thinking that the other bolts might be enough to hold down the head and i was wrong it drips slow. I cleaned the hole and i can see in side the hole the broken bolt should i try this myself or send it to a machine shop or drill it complete out and helicoil any ideas,

Re: 1986 150 evinrude number six plug has sludge on the plug

The head bolt hole is in a critical part of the powerhead. If you've drilled out bolts before, you can tackle this one. If you are not familiar with doing this-let an experienced mechanic do it for you. If done with skill, you may not need the helicoil.