Force 85 hp 1989 - Water in cylinder 3.

[Loozerdk]

Hi.

About a year ago i got a good offer on a Force 85 hp that the owner gave up on, finally had some time to dig into it, and got it started after replacing a burned out starter, but it only runs on the top two cylinders, number 3 in the bottom is taking on water, and steam cleaning the plug.

Engine is pretty clean, just got the powertrim replaced, and impeller replaced, so it would be nice to get it back onto a boat, running on all 3 cylinders.

Compression is good on all 3 cylinders (120 psi)

What should i suspect first, a blown head gasket, or a bad gasket at the exhaust cover ? I know some of the older Force outboards had a weak point on the gasket under the exhaust cover, but this is a 89 model, and a different kind of cover and gasket.

Kind regards
Ronni

 

[jerryjerry05]

Even with good compression the head gasket gasket can be bad.
Had a 88/85 with a miss and water on a plug.
The gasket had a pinhole and when changed, ran like a top.

 

[Loozerdk]

Even with good compression the head gasket gasket can be bad.
Had a 88/85 with a miss and water on a plug.
The gasket had a pinhole and when changed, ran like a top.

Thanks for the reply, looks like i need to snap every single head bolt then.

 

[jerryjerry05]

I forgot to say: the head bolts can be a B%$#& and worse.

Start with WD, PB Blaster and a propane torch and a hammer.

Spray with what ever penetrating oil you get.
Heat the bolt and surrounding area, get as HOT as possible.
Then spray again, heat and then tap the screw head and repeat.
Then ever so gently try to turn the screw.
There was only 20# of torque but the corrosion boosted that to 75+
You might/will twist off some heads but go easy and you might manage to get 1 or 2 out

 

[Loozerdk]

That sounds like a fun job, better start with the exhaust cover gasket, those bolts are at least not stuck, no reason to touch the head gasket if not needed.

 

[The Force power]

Stop!!! no need to open, the gasket will never reseal!!

Focus on the Head-gasket

 

[Loozerdk]

Stop!!! no need to open, the gasket will never reseal!!

Focus on the Head-gasket

So you are positive its a bad head gasket ? And its not sucking in water from the exhaust side ?

 

[Redbarron%%]

If you could borrow a compression leak down tester you could pressurize the cylinder and listen for where the air is escaping, It should just be from the intake or the exhaust and not from the water jacket. You could take the thermostat at the top of the head to listen. You have to put the piston at TDC and hold it there or the crank will turn as the cylinder is pressurized

 

[Loozerdk]

If you could borrow a compression leak down tester you could pressurize the cylinder and listen for where the air is escaping, It should just be from the intake or the exhaust and not from the water jacket. You could take the thermostat at the top of the head to listen. You have to put the piston at TDC and hold it there or the crank will turn as the cylinder is pressurized

In this case i guess it does not need to be a leak down tester, it should be enough just connecting regulated air to the cylinder correct, and lisiting for where the air escapes ?

If so, it should be able to couple something together using my compression tester and a regulator for air.

 

[The Force power]

So you are positive its a bad head gasket ? And its not sucking in water from the exhaust side ?

The only way water would be there....if the gasket between the power head & adapter-plate is leaking; then yes.
If you are worried about rusted bolts......they would be the ones!
my money is on the Head-gasket blown(happens more than you think)

Is this a Salt-water motor?

 

[Loozerdk]

The only way water would be there....if the gasket between the power head & adapter-plate is leaking; then yes.
If you are worried about rusted bolts......they would be the ones!
my money is on the Head-gasket blown(happens more than you think)

Is this a Salt-water motor?

It is a salt water motor yes, but a very well taken care of example, bolts on the exhaust plate is fine, as in not stuck, bolts on the cylinder head on the other hand are all stuck.

Maybe i should just order the two gaskets between the exhaust plate, and a new head gasket and be done with it.

 

[jerryjerry05]

Never heard of the adaptor plate gasket leaking water into the bottom cyl. EVER!!

Focus on the head gasket.
If you could find a shop to work on it??? they would do the head gasket first.

Since it's a salt water motor?? the exhaust chest will not reseal
easily unless you have the surfaces milled.
EVERY one I ever worked on leaked around the screws.
The corrosion eats away the mating surfaces and makes it almost
impossible to reseal.

Focus on the head gasket. Like you have already found, not gonna be easy.
Good luck.

 

[The Force power]

Never heard of the adaptor plate gasket leaking water into the bottom cyl. EVER!

I don't mean any disrespect Jerry,(because in my eyes, you're the Expert) but the sealing-point (looking at the gasket)from the water-tube is right beside the exhaust-cavity & I did not meant to imply that this was a common issue

 

[Redbarron%%]

The only force that I know will leak from the base to the cylinders are the ones used on the Mercury Sport Jets. Often the blocks have been replaced with outboard blocks and the water inlet to the exhaust log in the front port lower log is there and the wrong gaskets are installed at the base or the seal is poor and in this case water will happily fill the cylinders. On an outboard I think that the leaking water would just run down the exhaust and out, but I really know nothing about the outboard arrangement.

 

[jerryjerry05]

Redbarron%% said: On an outboard I think that the leaking water would just run down the exhaust and out,
Your right

 

[Loozerdk]

Redbarron%% said: On an outboard I think that the leaking water would just run down the exhaust and out,
Your right

I don't agree, i think the backpressure will suck the water into the cylinders, but i will start with the head gasket.

 

[Redbarron%%]

I know that the Sport Jet will fill up with water because the floor of the exhaust plenum is right below the cylinders, but at the same time this is usually a problem when on the hose and the engine not running and it will fill up pretty quickly. However there is no floor o in the exhaust plenum on the outboards as far as I know. With the jets they don't tend to get water in the cylinders running on the water.
I don't have any experience on the outboards, just the Sport Jets.

 

[Loozerdk]

So one bolt came out, the rest snapped, now next project is getting the cylinder head removed.

 

[jerryjerry05]

Sucking water back up into the motor.
The sportjet is setting way low in the water and it
could possibly suck water into a cyl.
But an outboard mounted right?? don't think so.

Small propane torch, PB Blaster or Krol and a pry bar.
Ge the area around the screw REALLLLLY hot.
Then spray with the sprays, then tap with a small hammer,
repeat, again the after a while try prying the head.
Use of an acetylene torch might melt the aluminum, so if
you use it be real careful

 

[Redbarron%%]

As to the jet sucking water back into the cylinder, with the water block in the exhaust loop I don't think that happens, but and this is a real big but, (like mine I guess) there are often outboard blocks installed that have the water passage in the front ot the exhaust log of the block. Also when the rebuilder sends the block often they send the wrong gasket that does not block off this passage from the bottom of the exhaust area and water will leak in, especially on the hose where there is water without the engine running, reducing the pressure in there, or more probably not blowing it out. Also in the sport jet the water that gets in here has no place to drain until it gets to the level of that loop in the exhaust, unlike the outboard.
If you have water getting into a Sport jet cylinder check for that hole, gasket and leak!!!!
Ask how i KNOW this!!!