97 Force 75 hp combustion problem

[Redbarron%%]

Don't use a steel brush but a scotchbrite will work ok
I use Permatex 85249 Hylomar universal blue so that I can remove the part and reuse the gasket.

 

[Creed1]

Is this the kind of scotch brite this one is a heavy duty or do I need the non scratching one?

 

[Redbarron%%]

I would use whatever that cleans the junk of.
Sometimes a single edge razor blade scraper will clean off the surface which is the whole idea.
When I redid the cylinder head on my 90 ho Sport Jet I sent it to the machine shop to just have a clean up pass on the head.
The block sometimes you can take a nice new flat file and drag it over the mating surface to get it clean .
Keep the file flat and use light pressure if you decide to go that way.
The hylomar will fill minor defects and also let you reuse some gaskets.

 

[jerryjerry05]

You'd have to really scrub hard with any scotch brite to do any damage.


No sealer needed, it's built into the gasket.

IF?? for some reason the head's removed after it's set/ran then silicone can be used
to make it seal again.

I use a thread cleaner kit and when installing the bolts, I use marine grease.
That way the next time you remove them they won't be so difficult!!

 

[Creed1]

I have replaced the head gasket replaced the thermostat & gasket but I still have the same problem. The top plug looks like choc. Milk.

 

[Creed1]

I removed the connector from the top coil with it running & the motor dies. I can feel a little shock from the plug wire when I pull it to remove it while it's running. But I can see it is getting fire to the plug.

 

[racerone]

Does spark jump a gap of 3/8" or more on all leads, yes or no.------Post # 1 says ---" seems to have good spark " ---and that means nothing here.

 

[Creed1]

[No message]

 

[Creed1]

[No message]

 

[Creed1]

Sorry I don't understand. Jump a gap of 3/8 or more. The middle plug seems to be firing harder than the top & bottom

 

[racerone]

Sparkplugs are NOT USED when you test for strong spark.----You use a testing device where ignition peak output is determined with a gap !!

 

[jerryjerry05]

This tester measures the jump of the spark.
Auto Zone .Under $8

If your still getting choc milk???

The head gasket's leaking, the block could be cracked?

 

[Creed1]

It jumps a gap at least 1/2 in. On all leads

 

[Creed1]

It jumps a gap at least 1/2 in. On all leads

 

[Creed1]

How can I tell for sure if I have a cracked block or head etc. or could it be something else?

 

[jerryjerry05]

Did you change the gasket or reuse the old?

 

[Creed1]

I put a new gasket on

 

[jerryjerry05]

There's only 3 ways for water in the cyl.
The gasket, the heads cracked, or the exhaust chest gaskets bad.
#3 would probably get water in more than one cyl.

Try running it and then let it set with the plug out.
Make sure the piston is all the way in to the bottom of the stroke.
Then set for a couple of days.
Maybe the rust will form and you can see if it forms on the cyl. wall ???

I had a problem with a Mercury 50 it kept fouling the plug.
Looked and looked and looked.
Finally got permission t dismantle.
Got it down to tiny pieces and finally noticed a shiny line on the intake side of the
cyl. port cover.
Tiny TINY little hairline crack.
Sucking fuel.

 

[pnwboat]

If the stainless steel exhaust baffle in the exhaust chest is cracked, it's not uncommon to get water in the cylinder(s). Number 17 in the diagram below. The exhaust chest gaskets that that Jerry refers to are number 16.

http://www.crowleymarine.com/mercury-outboard/parts/2014_12.cfm?mdl=MZD0SB

 

[Creed1]

Is it possible that the water jacket could have a crack in it ? Would that cause the water on the top plug?