Head Gasket for 25hp Johnson

Upon receiving a new head gasket for my '79 Johnson, I noticed that it was very
slick on both sides, similar to a silicone wax. I have never seen anything like it.
I called the distributor about using Permatex on it and he could not find anything
that said "not" to use a sealant.
I applied a thin coat of Permatex around the water channel areas and torqued down
to specs. Got all the parts together and installing the top spark plug and stripped
the *$&%U&$ threads !!!
Pulled the head and the new gasket just fell off ....... no Permatex stuck to it whatsoever.
Heli-Coiled the stripped threads and cleaned up the old gasket Permatex and reinstalled
the same head gasket - torqued to specs.
Engine ran GREAT off and on for an hour or so in the bucket - very satisfied.
Then, it started to chug - choke and exhibited signs of vapor lock ......
pulled the spark plugs and there is WATER on them !!!!

I know this is long .......... but ......... will be getting a new head gasket in a couple of days
and need to know what is this new silicone-waxed style of gasket ???
is there something to ad to it ? or just put it on and torque down to specs ??
I only want to do this one more time lol
Thanks

I believe the oem head gaskets have a sealer already on the gasket and the shop manual says to not add an additional sealer. Check the head for warping with a straightedge. It may need to be machined a little. After installing the gasket and warming up the motor the first time, let it cool and retorque the head. Sometimes the bolts get loose after this. I believe water can also get into the cylinders from bad exhaust cover gaskets or lower crank seals. Someone correct me if that's wrong please.

Everything above is pretty much spot on. The only thing I can add is that you need to check your water diverters in the block before putting it back together. If they are distorted and pushed over from any kind of previous overheat then you will probably overheat again or have an engine that is running well above designed limits. Pretty much anytime you have to replace a head gasket always replace these as well. These create proper water flow and cooling around your cylinders. You should see an obvious air gap around both diverters. If not....replace.

Thanks Guys,
I flat sanded the mating surfaces when I had it apart for the head rebuild.
New water deflectors (@ $10 a pop = $30) are pushed in until they bottomed out
then trimmed flush with cylinder head.
After I drilled out the Water Inlet Screen (which was in bad shape) and got that clear,
I have twice the amount of water out the pee stream now. (see photos).
After what NoHassle said about the lower part may be leaking, I did notice that my
water bucket was way up past the exhaust which may have created too much of a
downward pressure to force the water back up the exhaust ??? lol I can only hope
that is the case and not a whole nuther rebuild of the lower portion.
After I replace the head gasket probably Monday, I will drill a hole in the water bucket
as not to overfill past the intake plate.
With this particular model, I can not use the water hose muffs ................
I also replaced the original 25hp carb with a completely rebuilt 35hp carb and
I was really really surprised at the increased RPMs right away !!! It also is a smoother idle.
WAY smoother. Can't wait to get all the gremlins under control for a long summer of boating.


There is nothing more grand
than to be just simply messing
around in and old boat. POGO - 1960

Not sure I would have done this as a leak could cause the boat to fill with water.

hahahahhahhaaaa that is sooooooo FUNNY !!!

IF a leak ever were to occur, I am sure I would be aware of it
way before the boat filled with water !!!!

The plastic hose is the nylon reinforced kind - made for high pressure applications.
not to worry, it is only a DRAIN line - never under pressure.
It is bundled along with the wiring harness from the motor to the dash. LMAO

my primary reason for doing this is to insure I don't miss the pee stream being stopped
up or water pump going out - like with the Previous Owner - which suffered overheat damage.
I am sure many will agree that if you can tell if the water pump stops pumping water
BEFORE you see smoke coming from the engine, the better the end results will turn out.

on this particular Johnson 25 model, you can not see the pee tube from the drivers seat
without constantly turning your head every two minutes to check it.
My next project is to install a tachometer and remote heat sensor to the dash.

[url=https://www.tinboats.net/forum/viewtopic.php?p=347462#p347462 said:

Barefoot_Johnny » Fri Apr 04, 2014 2:11 pm[/url]"]hahahahhahhaaaa that is sooooooo FUNNY !!!

Click to expand...

Funny? man you have an odd sense of humor

Wouldn't worry about that either. Am thinking when your feet got wet you would know something was wrong way before you needed to worry.
Anyway.....I sure hope you got that one deflector in a lot.....a bunch.... farther that what the photo shows before you cut it off. There should only be about 1/8" showing when the are properly installed. If not then that is a do over.

Pappy - I posted an article last month about the deflectors .... my motor is 25E79R
https://www.tinboats.net/forum/viewtopic.php?f=4&t=33604
I got the top deflector in all the way. The two bottoms ones not so much.
Do they come in different sizes ?????
Now that I just looked on E-Bay there are two different styles.
The ones I got from Boats.net was solid rubber with a tapered end, very firm and hard to work with.
The other ones are like a tube with a hole through the middle... this is what I took out as they were
burned up pretty badly from a previous overheat.
I did everything under the sun to get them in more than what the photo shows.
On my motor, the two bottom chambers close down at the back and there was NO
way to get them in further than that. I tried Permatex as you suggested for lube.
Then, motor oil, silicone spray, put them in a vice to flatten them out then RUSH
to the motor, to no avail ... put them in boiling water, freezer, nothing worked.
so I cut them off about 1/2" from the head.
If you have a special way to get them in, please share it with us.
If you feel they should be ALL the way in, I will buy two more and make it happen somehow.
Regards.

Sometimes.....you have to clean out the pilot hole they fit into with a drill bit due to corrosion and or left over debris. I have had a tough time on occasion as well with them. But.....they have to go in all the way or very close to it. Stick something in the bore to the bottom and measure it and lay that measurement out on the diverter then you will know how far it needs to go in.
If you don't get them in you will effectively short circuit the cooling flow and create hot spots around your cylinders. Not good on a two stroke.

okay - got it !!
I ordered the other type of deflector, the type that looks like rubber hose.
This is what I dug out when I first removed the head - they were toasted from
from a previous overheat but I did get one out that looked like rubber hose.
I messaged the seller and he says the parts I am getting are actual OEM NOS.
He is liquidating his father's outboard repair shop and has lots of NOS stuff on E-Bay.

I did the all the tricks to get to the bottom of the Deflector Chamber - - -
So it is good to go once I get the correct item.
I just think that the particular item I used before was not for my motor.
As you can see in the photos, the hard rubber deflector is much different than
the tubular type. SO, if I can get it in half way, I am confident it will go in all the way.
THEN - the new head gasket torqued to specs, and it should be good to go.
I just hope and pray the water is not coming into the cylinders from another place
other than the head gasket being the culprit !!!!

ONE last question - and I will let this alone for now .....
Pappy - You said -

There should only be about 1/8" showing when they are properly installed. If not then that is a do over.

Click to expand...

- - do I cut off the 1/8" if it is indeed left over ? or push it in with the head install.

THANKS TO ALL that shared,
Johnny

reinstalled
the same head gasket - torqued to specs.

I am of the opinion that you cannot re-use any head gasket on any engine as they are designed to be crushed in order to seal properly. reinstalling one will only cause leaks