85 HP Force 1989 runs on muffs/not in water-Exhaust leak?

[JerrySzul]

Does white smoke within motor housing when try to start the motor in water indicate an exhaust leak? Motor runs fine on muffs but kills 20 seconds after starting when its in the water. When this happens, i see white smoke seeping out the top of the motor cover. The motor will then not restart until its back on land, hooked up to the muffs. The battery is new. I suspect the problem is exhaust related based on the forum posts I read previous to posting this and I have had many problems with the motor this year...now that it is running on land with the muffs, this problem comes up. Can anyone help me determine what the problem might be if leaky exhaust or something else and how involved the repair might be. I had previous posts regarding fuel lines and spark issues but seem to have moved past those issues and thought might be best to start a new post. Hope that's the right thing to do. Thanks.

 

[scottmm73]

Have you checked compression? I had the same issue and turned out my #2 and #3 cylinder threw their rings which scored the cylinder walls leaving less than desirable compression numbers. I ended up replacing the powerhead and rebuilding the old one. Now one sits on the shelf in case its needed.

Here is the link a post I created about the issue.

http://forums.iboats.com/forum/engi...5-hp-3-cylinder-compression-and-ignition-woes

 

[Nordin]

Jerry Szul, first do a spark and compression check.

If there is a exhaust leak the engine should start in water if you remove the cowl.

If it does not start there is more or another issue then exhaust leak.

 

[jerryjerry05]

You might need the rubber boot that's between the rear cover and the motor.
​Look down inside below the plugs and see if the clamp is good or the boot is split??

An exhaust leak between the block and the adaptor plate is common too.
You should be able to see a leak.
Way deep inside the exhaust meets the bottom of the mid section.
There is a seal there that can go bad and allow exhaust back up while in the water.
​Find a pic of the parts breakdown. boatsdotnet open the Mercury link and find Force and go to your year and go to the Motor Leg.
Find part #1 you'll see a square gasket that doesn't have a part # that's a seal that can go bad and allow fumes up into the motor.

 

[JerrySzul]

Thanks much for the info. Jerryjerry05-- I looked at the boats.net site and parts breakdown... very helpful. From what i see, I think it is the idle exhaust boot that needs replacing. Is boats.net a good site to order this part from or would it typically be available at most boat repair/marinas? How would i get the square gasket you mention? Does not look like it can be ordered from boats.net -- listed as obsolete. Not sure I'll need it but just wondering. Is the boot difficult to install?

 

[jerryjerry05]

That part usually can be found on line.
If a marina had one it would probably be used and you don't need a used part.
That site I sent you to is about the cheapest unless you can find it on e-bay.
E-bay has them but it seems they want WAY more $
Not hard to replace.
Use a stainless clamp.