1997 120Hp Force one cylinder not working?

[pnwboat]

Re: 1997 120Hp Force one cylinder not working?

That part of the diaphragm is exposed to the intake pulses and fuel/air mixture sucked into the engine from the carburetors flowing through the bypass passage on it's way to the ports that feed the fuel/air mixture to the cylinders. It sure looks like water is mixed in with the gas. May not be contaminated gas tank. It may be leaking in from another parts of the motor, but the best thing to do is to hook up a portable gas tank and see if you still see any milky stuff.

If you stored the boat with an empty tank, there's a good chance that you may have gotten a lot of condensation inside the tank.

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

The picture on the left is the onboard tank run for 5 minutes
The picture on the right is a portable tank (with new gas) run for 20 minutes.

My camera isn't taking clear up close pics tonight for some reason??? if it was I would have posted a picture of the #3 spark plug with a milky white substance on it. The #2 didn't look that good either. #1 & #4 looked normal.

A couple other observations that may help (or confuse things even more):
After letting it idle for a few minutes, I rev it up and there is a lot of white smoke. At first I thought it was because of the Seafoam/De-carbing, but that should be gone by now.
#2 I need to get the rpm's up to 1500-2000 before water comes out the "pee hole". It used to spit when idling and pee when just above idle.

 

[jerryjerry05]

Re: 1997 120Hp Force one cylinder not working?

The diaphram first pic.
NO way water should be in there!!!
I'd bet a head gasket problem.Or a crack in the block somewhere.
No way the water(if there is water in the gas) should it get to that side of the diaphram.
Diaphram pics.
The diaphram should be a lot smoother and not so streched.It will work just not as good as it should.
The (pee hole problem)
With a good impeller it should pump a LOT of water at a slow idle.
Possible the exhaust housing is full of crap,restricting the flow.

It's not that expensive to replace the head gasket.
A whole kit can be found for $60+
Without being able to touch it in person.I'd say that's the thing I'd do first!!

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

Sounds like the head gasket is the plan.

Hopefully my next post will be a good one...

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

See anything obvious? Hard to tell from the pictures I'm sure.


I don't see anything obvious except water in #3 ( and #1 running rich).
Should I see a failure with the head gasket?

Jerry, you mentioned a "head gasket kit". I'm not finding a kit. I see a variety of head gaskets. What is in the kit?

 

[pnwboat]

Re: 1997 120Hp Force one cylinder not working?

You can definitely see something wrong with #3 cylinder. Gasket itself looks OK from the pictures. I would begin to suspect the exhaust cover gasket(s) may be bad. Put a new head gasket on it and see if it makes any difference. If not, then the exhaust cover gasket(s) may be leaking water. The head gasket and exhaust cover gaskets are the only two places that will allow water to get into the motor if they fail.

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

Are you refering to the exhaust plate gasket on the bottom of the powerhead, or the exhaust plate gaskets on the side of the powerhead?

 

[pnwboat]

Re: 1997 120Hp Force one cylinder not working?

The one on the side of the powerhead.

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

I replaced the head gasket, no change.
I replaced the exhaust plate gaskets and I now have great water pressure! The water is coming out the pee hole stonger then ever. The problem is the water is going into the cylinders stronger also...
When I took off the exhaust plates I could see that the water was cleaning around the #3 cylinder a lot and around the #2 cylinder a little.
Now that the gaskets are replaced, I am seeing quite a bit of water on the #3 plug and a little water on the #2 plug.

It doesn't sound like I'll be on the water this weekend...or next....

 

[pnwboat]

Re: 1997 120Hp Force one cylinder not working?

Take a close look at the stainless steel exhaust plate (#33). You may have a crack that's allowing water to squirt into the cylinder(s).

http://http://www.crowleymarine.com/mercury-outboard/parts/2009_120.cfm

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

Thanks, I saw that as a possibility in another thread. I did inspect it and it looked normal, no cracks, a bit warped.
Other than a crack (which I didn't see either) is there any other way for water to get in there?

 

[pnwboat]

Re: 1997 120Hp Force one cylinder not working?

I'm sure there are other ways for water to get in there but can't think of any off hand. If I were a betting man, I'd say the there's either a crack in the exhaust plate, or maybe a small chip or defect somewhere along the sealing edge of the exhaust cover. You may have to take some carburetor cleaner and really clean the plate off well to inspect for a crack. Just a hairline crack is all it takes. Might have to flex the plate a little for the crack to show up.

You can also try using some sealant on the gaskets. I'd recommend some Permatex Ultra Grey. Use some carburetor cleaner or Acetone and clean the sealing surfaces off real good. Use the sealant sparingly. Don't want any excess to squeeze out and block the water passages. Let the sealant set up for a couple of hours before firing the motor up.

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

I'm sure there are other ways for water to get in there but can't think of any off hand. If I were a betting man, I'd say the there's either a crack in the exhaust plate, or maybe a small chip or defect somewhere along the sealing edge of the exhaust cover. You may have to take some carburetor cleaner and really clean the plate off well to inspect for a crack. Just a hairline crack is all it takes. Might have to flex the plate a little for the crack to show up.

You can also try using some sealant on the gaskets. I'd recommend some Permatex Ultra Grey. Use some carburetor cleaner or Acetone and clean the sealing surfaces off real good. Use the sealant sparingly. Don't want any excess to squeeze out and block the water passages. Let the sealant set up for a couple of hours before firing the motor up.

Good advice! I will try that before I throw in the towel.

The sealing edge was very clean, but like you said...it only takes a hair line.
I didn't flex the plate to much while inspecting, I was afraid I might damage it.

 

[pnwboat]

Re: 1997 120Hp Force one cylinder not working?

That stainless steel plate is pretty tough stuff, so you don't have to worry about damaging it, Just don't go overboard. When stainless steel is heated up, it has a tendency to get hard. I know this first hand in trying to drill through a thick piece of it. Typically the harder the steel, the more brittle it gets. The plate is very close to the exhaust ports so I would imagine there's a chance that it could get pretty hot if water flow is not up to par. I've seen a few of those plates that have cracked. In all cases, it's been the 1995-1998 series of motors. I don't know if they changed the type of stainless steel used in those year motors but just something that sticks out in my mind.

 

[swick]

Re: 1997 120Hp Force one cylinder not working?

Another thought, when you put the new head gasket in, did you torque everything down properly or did you just tighten the head with a regular wrench? It could be possible for water to get in between the head and block, even with a new head gasket, if not properly torqued.

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

Another thought, when you put the new head gasket in, did you torque everything down properly or did you just tighten the head with a regular wrench? It could be possible for water to get in between the head and block, even with a new head gasket, if not properly torqued.

I did torque to specs and proper sequence. Still getting great compression also.

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

That stainless steel plate is pretty tough stuff, so you don't have to worry about damaging it, Just don't go overboard. When stainless steel is heated up, it has a tendency to get hard. I know this first hand in trying to drill through a thick piece of it. Typically the harder the steel, the more brittle it gets. The plate is very close to the exhaust ports so I would imagine there's a chance that it could get pretty hot if water flow is not up to par. I've seen a few of those plates that have cracked. In all cases, it's been the 1995-1998 series of motors. I don't know if they changed the type of stainless steel used in those year motors but just something that sticks out in my mind.

I took it back out. I still don't see a crack. I do see quite a bit more water in there though (as expected).

I read in another thread that it is normal for those plates to be warped which lead me to believe that mine is normal. However, I think I'm going to order one anyway and see if it helps. I find it hard to believe that it can flatten out and seal properly in the condition that it's in.

It does appear that water did make it between the plate and the gasket. I'm just not sure if that happened while I was testing it, or while I was taking it apart.

 

[pnwboat]

Re: 1997 120Hp Force one cylinder not working?

Yeah I've seen some that were really warped and I had doubts about re-using them but I did and they didn't leak. If you suspect water got between the plate and the gasket, then maybe a new plate and a little sealant might be in order. Be sure to give the sealant enough time to set up. Make sure the bolts are the proper length. These motors have been around for a while and you never know if some previous owner has changed them. These bolts in particular have a tendency to corrode and break off. If they're too long, they won't pull the exhaust cover/plate down tight enough. From what I can remember (the old mind is not what it used to be), the exhaust cover bolts were an odd length. Not commonly available. The most common available bolts are like 1/4" or so longer. You can also use a washer under the bolt head to take up any slack if need be.

 

[onthechip]

Re: 1997 120Hp Force one cylinder not working?

Well,..The new exhaust plate, gaskets and sealant did not help. I have the exact same symptoms. Besides explosives,...any other suggestions?

 

[pnwboat]

Re: 1997 120Hp Force one cylinder not working?

I would have think about this one but I suspect a crack in the water jacket somewhere in the block.