1991 9.9hp johnson

[Zboats]

Hey guys,

I had my 1991 9.9 johnson running at the house, hooked up to the hose and running fine.Motor was pissing water fine, I turned up the throttle a little and all heck broke loose. It made some bad clanking noise. So, I hit the kill swithch right away. I was looking in to the noise and found a broke spark pulg in the lower piston and the motor would spin. So I put it away knowing the motor was a loss. Then I looked at the motor the other day and the flywheel spins. however, it get to one point and is really tough to spin. Any ideas what happened? Is it worth fixing?

Thanks for your help,
zboats

 

[racerone]

Re: 1991 9.9hp johnson

Take the cylinderhead off and have a look in there.

 

[Fleetwin]

Re: 1991 9.9hp johnson

Take the cylinderhead off and have a look in there.

Yes, +1.

 

[Zboats]

Re: 1991 9.9hp johnson

We'll guys I took the cylinder head off and the top piston is normal. The bottom piston was super clean. But, There was metal shavings or grit in the bottom cylinder . However there are no groves in the cylinder wall. I don't know where the metal shavings or grit came from. Maybe when the spark plug broke? Then, The piston ring on the bottom cylinder was catching the top of the cylinder wall once the piston reached top dead center. Which was making going the flywheel hard to spin. This is happening only in the bottom cylinder. Also it appears the piston hit the spark plug there is a little dent in the piston where they hit. So, I looked at the plug and there is no gap.

What caused all this?
Did the motor get hot and expand the piston ring?
Could some thing have broke in the crank allowing the piston to come out of the cylinder, which would allow the piston to hit the spark plug and allow the piston ring to catch the top of the cylinder wall?


Thanks for you help

 

[racerone]

Re: 1991 9.9hp johnson

I woud think you have some serious internal issues.----Does bottom piston move the same as the top ?------When bottom piston is moving down in the cylinder and you push on it what happens.-----How does that compare with the top ?

 

[oldboat1]

Re: 1991 9.9hp johnson

as to cause, were the right plugs installed? that is, too long?

 

[Zboats]

Re: 1991 9.9hp johnson

Yes the bottom piston moves the same as the top. And when I push bottom piston it doesn't nothing, if it goes down the top piston comes out respectively.

 

[raczekp1]

Re: 1991 9.9hp johnson

take powerhead out and spleat crank case.
if you are lucky in 3 hours you will done to split and put back all parts

 

[racerone]

Re: 1991 9.9hp johnson

If it appears that there are metal bits and damage to the piston ring then the motor needs to come apart.---Then you will be able to why / what happened.

 

[boobie]

Re: 1991 9.9hp johnson

Tear it down.

 

[naturelover]

Re: 1991 9.9hp johnson

Bad rod bearing?

 

[boobie]

Re: 1991 9.9hp johnson

Or wrist pin ??

 

[Zboats]

Re: 1991 9.9hp johnson

I thank you guys for all your input.
Im going to open her up and see what happen. I will let you know what I find.

 

[Zboats]

Re: 1991 9.9hp johnson

Guys hope u can help again,
I m trying to get the fly wheel off and it not happening. I'm using a harmonic balance puller using the 3 threaded holes and it not coming off. I've sprayed it with WD40 not like that would help but I did. I have tightened it down and let it set and tightened it more, the bolts are now bending.
Any suggestion on how to get it off with out cracking it?

 

[racerone]

Re: 1991 9.9hp johnson

You give the center bolt a good bump with a hammer and it should pop off.

 

[nwcove]

Re: 1991 9.9hp johnson

lift up firmly on the puller while tapping it with a hammer!!

 

[oldboat1]

Re: 1991 9.9hp johnson

Your puller will work, but be careful not to strip threads. Don't use bent bolts. Loosen the flywheel nut, and raise it up on the shaft up a little above the top of the shaft (to protect the shaft). Go ahead an give it a whack or two, straight down. Assemble the puller with new bolts. Crank on the post of the puller with a box wrench or socket. Don't use something that is going to slip off, like a crescent wrench. Turn it clockwise, and tighten it up snug. Whack on the shaft of the puller, and tighten again a little more. Continue until it sounds like you just broke something, and check to see if the flywheel is loose. When it's loose, it's going to pop up only to the nut -- another reason for keeping the flywheel nut up there. When it's free, you will be able to wiggle the flywheel with your hands. By the way, wear leather work gloves for this stuff, and keep head, hands and arms out of the way. It can be kind of violent.

 

[Zboats]

Re: 1991 9.9hp johnson

Racerone you know your stuff it took three good taps on the puller and it popped right off.
Thanks I will keep you all up dated on what I find

 

[Zboats]

Re: 1991 9.9hp johnson

I found the problem fellows,
Bad rod bearing on the lower cylinder.


I have a few questions;
1. Do I replace the rod bearing in the top cylinder as well?
2. what else should I replace while I have the powerhead off and tore down?
3. What caused this? So I can avoid this problem in the future. Possible overheating or just wore out part?

 

[racerone]

Re: 1991 9.9hp johnson

Pictures of parts ?-----What boat ? -what prop ? what oil are you using etc, etc ---Post all the facts for answers.