Force 90HP 1990 exhaust leak

[sdxp787]

Have a 90HP Force on my 22 ft pontoon. I was running it the other day with the cowl off and noticed exhaust coming up from under the motor. I did some research and decide that it must be the seal between the motor leg and adapter plate. I commenced to performing this time consuming task. Finished it up and it still smokes from underneat the motor. I have checked the "idle tube" as it is called that exits out the back of the motor leg cover. It has the accordion type shape. It has no tears. I am stumped. As you know, exhaust going into the intake is bad news. And it goes into the intake very willingly. Does anyone know what this could be? It idles poorly with the cover on, obviously.

 

[sdxp787]

Re: Force 90HP 1990 exhaust leak

Anyone? The leak is not very evident. I would assume that I would see some residue from the area leaking, but there is nothing. This is killing me. Our first boat and I can't have any fun with the family because of this. Help!!

 

[Frank Acampora]

Re: Force 90HP 1990 exhaust leak

There may be no tears in the rubber bellows, BUT: Is it seated correctly into the tapered seat in the rear cowling? Is the internal spring present? Has the plastic insert in the rear (where it seats) melted or not present? Has the spring clip fallen off so the other side is not secured to the engine leg?

This exhaust bellows has a spring and white plastic seat inside it. When the bellows is attached to the stub on the leg, the spring pushes the plastic and the taper on the bellows against the seat.

If the spring clip has rusted and fallen off, simply replace it with a large electrical tie. Push the bellows hard against the leg and tighten the zip tie.

To check most of this is easier if you remove the rear shroud. Once you remove the rear shroud, also check the bottom gasket that supposedly seals it against the engine leg. If this foam gasket is deteriorated or missing some exhaust can be aspirated into the cowl at idle.

 

[sdxp787]

Re: Force 90HP 1990 exhaust leak

Frank,
I checked the bellows tube last night and it is not torn, the spring is in it, and so is the retaining clip. I had a hard time keeping all the smoke from the exhaust away from the area I was trying to inspect. So, needless to say, I gotta start over . i am thinking of putting some high temp sealant on the tapered tip of the bellows where it makes contact with the motor leg cover to see what that does.

 

[sdxp787]

Re: Force 90HP 1990 exhaust leak

I think I found it. The gasket on the motor leg that supposedly seals the two halves is leaking. I tilted the motor forward and poured some water on the top side of the gasket and all the water leaked out the front. I am going to assume this shouldn't happen. Since this gasket is no longer available, how should I seal it?

 

[sdxp787]

Re: Force 90HP 1990 exhaust leak

I think there is more to the story here. I noticed that I am getting exhaust coming up by the shifter rod that comes from the lower unit to the motor leg. I thought to myself, why is that coming from there. I looked through my manual and online at some parts pictures. There is no gasket between the lower unit and motor leg. The manual does not mention using any kind of sealer. Why? If I am getting exhaust through this area, it should be sealed. Now, the other question is, is my lower unit correct for the motor. The motor is a 1990 90HP but I am sure the lower unit is from an 85HP. Was there a difference in these two lower units? They bolt right up. I wonder if the sealing surfaces are off just enough to cause me to get exhaust into this cavity and have it make its way to the front of the lower unit and up and out by the shifter rod? Does anyone have experience with the lower units between the 85 and 90 HP models? Are they the same?