Corrosion on cylinder wall johnson 9.9

[maineiac5586]

Hi. I just bought a 2005 johnson 9.9 2 STROKE. Owner said it was good to go (lied). I started it up easily enough on the stand once I got it home from buying it. Once it warmed up it stalled and didn't want to stay running (I checked COMPRESSION and got 70 PSI top 60 PSI bottom. I know it should be 110 PSI plus. I see the head got super hot at one time so I pulled the head off and think it has a bad head gasket.(on the side that faces the head there is a split between the 2 CYLINDERS (the other side of the gasket has no split in that location. I checked the head for warpafe as well as the sealing edges of the cylinder liners. All seems ok. Question is that there is CORROSION on the cylinder liner that is coming close to the metal sealing rings of the head gasket. It looks like it hasn't made it to where the metal cylinder head ring needs to seal. I need opinions on just putting a new head gasket in or do i need to scrap the whole power head . Thanks
see pictures attached.

 

[Crosbyman]

me… I would change the head gasket … rebolt it up to specs run it rebolt it up again to specs

rust.. well it is there could be just surface rust in the cyl. due to that bad gasket leaking...and dropping your PSI readings

it is your motor now so just oil it up , run a tank at 24/1

it may live again and live long like my seized up 9622a 9.5 which I paid $50...cdn

 

[maineiac5586]

check the pics, I just attached

 

[Newyota]

I agree with crosbyman..My brother has one with similar compressions and still running it..It had overheated and blew headgasket..He was lucky and it still had life in it.He also discovered thermostat came apart.

 

[Crosbyman]

I am amazed at how negligent owners can be. that engine cyl. head looks terrible I hope therest of the engine was not mistreated as much.


looks aside it may be a runner so invest in a gasket and see what happens

 

[maineiac5586]

Do you all think that the split between the 2 CYLINDER holes on the gasket in the picture is enough to cause those low COMPRESSION readings?

 

[racerone]

Pull the exhaust cover and inspect pistons and rings.------Not sure why you would buy one with those signs of overheating.-----Hopefully you did not invest that much coin.

 

[Crosbyman]

btw that other parts site does not list a 9.9 in 2005 what is the mdl # on your plate ????


9.9 hp stops listing in year 2000 ????

 

[racerone]

No they made them up to 2007.----Under the 10 models not 9.9.

 

[Crosbyman]

up here in Canada a 10hp needs a boat registration # so <10 hp were very popular

" No they made them up to 2007.----Under the 10 models not 9.9. "


so what does he have a 9.9 or a 10 ​

…. if the cowling says 9.9 would it not be earlier than year 2000 ?

 

[maineiac5586]

COWLING says 9.9. MODEL NUMBER is J10RSRD WHICH BOATS.NET HAS IT AS A 2004. Production date on sticker tag on swivel bracket is 07/2003.

 

[racerone]

???----The cowlings will say 9.9 but the model designation is a 10 for all of them up here in Canada too.

 

[maineiac5586]

Yes that is correct.

 

[maineiac5586]

So back to my post lol. Anyone know if the damage on the head gasket shown in my pictures would be enough to cause a drop in COMPRESSION on both cylinders?

 

[Bosunsmate]

So back to my post lol. Anyone know if the damage on the head gasket shown in my pictures would be enough to cause a drop in COMPRESSION on both cylinders?

Since none of us a there to inspect its intricacies id say it could be but is more likely to be a stuffed headgasket.
Smooth it out and put on a new headgasket and see how that experiment goes

 

[OptsyEagle]

Also, why did it overheat? Did you verify that it was pumping water when you fired it up. Certainly keep an eye on that if you get to run OK.

 

[maineiac5586]

Pumps fine but I am going to replace the water pump Any way and the thermostat.
I sent a message to the seller with pictures but never heard back from him (imagine that)

 

[Crosbyman]

buyer beware they say....

buying oldies or dirty newer engines requires some precautions but to late now.

 

[oldboat1]

Think I would use some ATF in the cylinders. Head cover in place (plugs out), slowly rotate flywheel by hand, repeat. Before reassembly with fresh head gasket, resurface the mating surface using sandpaper on a flat surface (get an equal shine all around). Torque to spec, using circular pattern starting in the center. I would use the standard 50:1 mix when it's time to fire it up, testing with fresh gas -- use a barrel rather than muffs, or try it in the lake.

 

[racerone]

Discoloration of the paint suggest severe overheat.----Remove exhaust covers too inspect pistons / rings !!