What would cause this?

[Chaz Hickcox]

So the picture is of sludge coming out of my exhaust on my boat. This is becoming a normal occurrence. Right now I am having issues starting the motor. It will kick over if I fog it, but it will not stay running. It seems like there is a lack of gas going into the system. I pulled one of the intake manifolds off of the carb and it seemed clean enough not to have to check the others (not saying that's not an issue, there are five others I did not look at). I checked the float in the central fuel system and that is good. There is fuel going through the system because I tested it by removing the lines to see if it would flow. I am thinking it is some gunk in the carbs, but I am currently at a loss. The sludge looks to me like burnt oil, but...

The last few times I had it running on the water the engine would randomly overheat. Water pressure is good (20-25 PSI) and it has plenty of oil.

The engine is a 1993 Johnson 60* V6 Loop Charged 150 HP Silver Star Series.

I working on it myself because the local shops are backlogged for two weeks. Thanks in advance

[Nitrofreak]

Looks like you may have a head gasket issue.

Have you pulled the plugs and tested compression or checked the cyls. for water intrusion?

[Way2slow]

The black deposits is not uncommon, that could be from running rich.

The crappy running is a problem and could lead to a major breakdown if not corrected.

Here's something you might want to look at also:

  PROBLEM:

Internal water cavity leaking

into #1 cylinder.

Engine: 1991 & up carbureted

150/175 HP 60 degree V-6 Evinrude

and Johnson outboards (6V-6 Eagle)

Description: Approximately 25% of

the 6V-6 blocks we test will show a leak

into the #1 cylinder from the center water

cavity underneath the regulator/rectifier. In

certain cases, a leaking engine may develop a

knock at around 3500 rpms. The sparkplug

may also show signs of water, and the cylinder

head's combustion chamber, piston dome,

and/or exhaust port may show signs of being

steam cleaned by water. It is important to note

that some engines in the early stages of

leaking may not show the mentioned

symptoms and can only be detected by

pressure testing the block.

Cause: The leak develops from a thin section

in the block.Due to engine vibration,

varying pressures, expanding and

contracting, the aluminum cracks

over time and causes water to leak

from behind the sleeve.

Repair & Results: MarFab can provide

its dealers with a remanufactured block

or powerhead, or can repair the leaking

block by welding and re-sleeving.MarFab

has been repairing 6V-6 leaker blocks since early

2002. Blocks are pressure tested after all work is

performed to ensure proper repair has been

made.