Piston heads - cleaning advice?

H

hempfarmer

Petty Officer 3rd Class
Joined
Oct 13, 2009
Messages
80
Hi everyone,

I am in the process of waking up a 1960 Johnson 5.5HP seahorse that has been sitting for 20 years.

My small bore hole light arrived so I took a look inside the cylinder. The walls look fine but the top of the pistons are covered in carbon. (crusty looking)

Should I take the head gasket off and clean them up? If so, is there a best practice for how to clean them?

Thanks!
Russ
 
HighTrim

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: Piston heads - cleaning advice?

What is the compression?

If poor, I would do the head gasket and manually clean.

If good, just do a decarb and leave the head alone. Seafoam or OMC Engine Tuner are good for this.

Where on Lake Ontario are you?
 
Chinewalker

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Piston heads - cleaning advice?

I concur - if it ain't broke, don't fix it. A decarb should take care of most of the gunk... assuming all else is good in the compression department...
 
H

hempfarmer

Petty Officer 3rd Class
Joined
Oct 13, 2009
Messages
80
Re: Piston heads - cleaning advice?

Compression is 79 and 81. Would you replace the head gasket or just leave as is?

I don't think it is the original head gasket since it looks like those bolts have been removed in the past.

I have a summer home in the Kingston area.
 
Chinewalker

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Piston heads - cleaning advice?

I would leave it alone. Those numbers are fine for that motor.

LOVE the Limestone City! We try to get over there a couple times a year.
 
HighTrim

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: Piston heads - cleaning advice?

Yeah I would leave that be.

After running it, and a decarb the number will come up some. You by no means are going to get 100 psi on that little CD, I would be happy with 80.
 
jmendoza

jmendoza

Petty Officer 1st Class
Joined
Jun 9, 2008
Messages
314
Re: Piston heads - cleaning advice?

I bought a new set of head gaskets (they came two to a pack from Sierra) and removed my head, and put one piston at TDC and scraped off the carbon, then repeated for the other cylinder. SOS pads work great for cleaning the combustion chambers. I lapped the head on a surface plate using medium emery cloth and replaced the head with a new gasket and torqued it down( repeat after 1 hr running). Interestingly, while doing the de-carb, I found paper towel debris inside which was blocking the cooling passages and removed it, as the engine had a history of overheating; this is why the previous owner gave up on it and gifted it to me!
 
You must log in or register to reply here.
Top