1977 Mercury 50hp sludge in cylinder

[kens]

I was doing compression chk on motor and when I got to #4 cylinder I noticed that the plug was white and not discolored like the other 3.<br />I then probed inside with a tie wrap and it had a silverish gray looking sludge on it.<br />I chked each cylinder and only #4 had the stuff in it.<br />The compression chk showed 110 in #1 110 in #2 <br />100 in #3 and 120 in #4, so I am guessing its not a ring or blown head gasket, so what is causing it.<br />Also before I bought motor previous owner said it sat for some time in a shed by a lake. <br />It was probably not used for a yr or more.<br />

 

[Yepblaze]

Re: 1977 Mercury 50hp sludge in cylinder

A white (clean) plug will indicate water in the cylinder during operation. Kind of steam cleans the plug.

 

[kens]

Re: 1977 Mercury 50hp sludge in cylinder

Ok then if it is water then where is it coming from? And mostly will it harm my motor to run it like that?<br />Could this be from not running and was formed by condensation? the sludge that is.

 

[rickdb1boat]

Re: 1977 Mercury 50hp sludge in cylinder

ken <br />Usually when you have the sludge, it is a sign that oil has mixed with water. But if you haven't run this motor yet, I'd get a new set of plugs and run it for a while and re-check the plugs. It could be from condensation. Hard to tell without seeing the plugs.

 

[kens]

Re: 1977 Mercury 50hp sludge in cylinder

3 of the plugs were normal as in they were blackened by use but the fourth was like a an off white and it looks like maybe rust crystals on it. <br />The plug still fires like the ****ens and its probably a pre 90s plug (AC 40 FF ) or something like that. I did run the motor on the old plugs and it runs a little ruff but I think its the old plugs or a little crud in one of the carbs because the float was stuck at one point, then started working right.<br />Could it be a cracked water jacket or maybe a gasket? that the water is coming from.

 

[DJ]

Re: 1977 Mercury 50hp sludge in cylinder

kens,<br /><br />Typically, water ingestion is from a cylinder head gasket or exhaust cover gasket leaking. Neither is a difficult job to take on.

 

[kens]

Re: 1977 Mercury 50hp sludge in cylinder

But wouldn't there be a compression lose if it was a gasket

 

[DJ]

Re: 1977 Mercury 50hp sludge in cylinder

kens,<br /><br />Not necessarily. Water has a sneaky way of creeping in on the intake stroke of 2-cycle engines.<br /><br />It doesn't take much to make a mess like you're looking at.

 

[Walker]

Re: 1977 Mercury 50hp sludge in cylinder

I don't believe that motor has cylinder head gaskets. It has intergral heads so your water must be coming from somewhere else.

 

[DJ]

Re: 1977 Mercury 50hp sludge in cylinder

Exhaust cover gaskets are likely suspects.

 

[kens]

Re: 1977 Mercury 50hp sludge in cylinder

how difficult to change?<br />Can a novice do the job without shop help.<br />I can't see spending a whole lot of money on a motor that old

 

[Chinewalker]

Re: 1977 Mercury 50hp sludge in cylinder

It's pretty straight-forward. Get the new gaskets from a Merc Dealer or NAPA, remove the exhaust cover plate and water jacket, clean up the surfaces, replace the gasket and torque bolts appropriately. A manual is recommended...<br />- Scott

 

[ODDD1]

Re: 1977 Mercury 50hp sludge in cylinder

Kens,more than likely the water you are getting in #4 cyl is coming from the exhaust plate/gaskets...these motors used an aluminum internal exhaust plate, which do corrode through....repair is not a huge deal, but you will be lifting the powerhead off the midsection, and dealing with corroded fasteners on the exhaust plate...