Pulled heads, took pics. Opinions needed

[CarlCVX20]

Pulled the heads from my '78 black max 200. Never done this before and don't know what to look for. It doesn't seem to be all that bad but could use a more experienced opinion

The cleaner looking head is from the port bank. The starboard head is yellowish and isn't very smooth, almost sticky like.

Do the pics reveal anything about my engine?

Thanks in advance

[FUJIMO]

Do the pics reveal anything about my engine?

...yes. it tells us that you have a very nice original chrome bore 2.4 merc v-6 that did not need to be taken apart......

[FUJIMO]

...put the heads back on with new gaskets & do not overtighten the head bolts...

[ChrisCarsonMarine]

Picture 5 looks to be pretty scuffed up at 8:00,what was the compression before the head removal>,Chris

[CarlCVX20]

Picture 5 looks to be pretty scuffed up at 8:00,what was the compression before the head removal>,Chris

Yup, comp tested 105 on that cylinder. The others were either 115 or 120.

[CarlCVX20]

What are the thought on the heads looking so different from one bank to the other?

[ChrisCarsonMarine]

No Worry,Not much different,But the scuffed cylinder needs checking out,and I expect a replacement piston and ring set,cyl wall may clean up,hopefully it's just melted aluminum from a hot piston...Scotchbright and muriatic acid.Careful wuth the acid,apply sparingly with a Q tip,and after a few seconds use the scotchbrite,repeat till the aluminum is gone,and see if the plateing is damaged,DON"T be sloppy,Chris

[David - WI]

What are the thought on the heads looking so different from one bank to the other?

One side running cold at idle? Stuck thermostat?

[CarlCVX20]

One side running cold at idle? Stuck thermostat?

my thoughts initially but did the thermostat test in a boiling pot of water and both opened at the same time and at around 140 degrees give or take. Thermostats are good.

[FUJIMO]

...on the older chrome 2.4's, number 5 was usually always the cylinder that started problems, due to the cylinder not being jetted rich enough... but chris can offer his assistance on this better than i...

[CarlCVX20]

No Worry,Not much different,But the scuffed cylinder needs checking out,and I expect a replacement piston and ring set,cyl wall may clean up,hopefully it's just melted aluminum from a hot piston...Scotchbright and muriatic acid.Careful wuth the acid,apply sparingly with a Q tip,and after a few seconds use the scotchbrite,repeat till the aluminum is gone,and see if the plateing is damaged,DON"T be sloppy,Chris

it concerns me that this will reduce compression even more, if i start rubbing down the cylinder wall as you suggest. I don’t want to change the size of the bore by doing this.

[rock]

You won't change dimensions with scotchbrite unless you are superman or something. Let the acid do the work, not force.

Rock

[keefallan]

You are just removing the aluminum thats been deposited on the wall. Many of us on here have done this before. I was a little leery on my first one. But, theres nothing to worry about. But do just as Chris stated.......dont be sloppy. Control the amount of acid put down. And when you are done wipe it down with oil. The acid dissolves the aluminum.........and likes to rust metal...........dont ask how I know ........but I didnt have chrome bores either.

[kellytheaker]

Guys I have only used Muriatic acid for rust work or cleaning the hull and such at the end of a season .
So do you neutralize the acid with water right afterwards then oil ?

[keefallan]

When I used it, my block was bare, so I washed mine with hot soapy water, and then wiped it down with two stroke oil.