Johnson 18 hp exhaust leak questions.

[flintcreek]

First off the search engine helped me figure out I have a leaking exhaust. The motor is a Johnson 18 Hp. model FD-19. With the hood off it will open up and run on top end put the hood back on and it smothers down (exhaust leak).
Pulled power head, removed side exhaust cover and inner exhaust plate, gaskets looked good, bottom 2 bolts were some what looser than others. Checked gasket on bottom of power head to mid section and it looks good. Now when looking at parts diagram and manual it shows a cover plate or baffle plate between the power head and mid section, my motor does not have this plate, is it used on all models? If it is missing would it cause a exhaust leak? Does the Crankshaft seal to this baffle? I have 3 different manuals, but they do not show a good view of the lower crankshaft seal.

Thanks,
Flintcreek

 

[F_R]

Re: Johnson 18 hp exhaust leak questions.

That baffle plate is to help keep the exhaust and water away from the crankshaft seal area. It does not actually touch anything, just a shield. It would not cause the problem you are experiencing.

In fact I have to ask if you actually have a problem? Are you running the motor on a boat, or in a tank? If in a tank, that explains it. Get it out of there and put it on a boat where it belongs, and it probably will be fine.

 

[flintcreek]

Re: Johnson 18 hp exhaust leak questions.

F_R...Thanks for the reply. I am running it on the boat out in the river. I tried to shorten the post and guess I left that out. Until I did my search last week I did not know that running it in a tank would cause a problem. When I take it out it idols fine, but will not open up and run or plane the boat off like it should until I take the cover off, then it will open up and run. Would you put it back together without the baffle or order one and put it together with one? Also it is going to be a week or so on the baffle and side plate gaskets if I have to order them has anyone ever used the red silicone for heat on exhaust gaskets? My son is a car mechanic and says it will work. Hoping to get it on the water ASAP, but want to fix it right...I have new gaskets for the power head to mid section already here to install.

Thanks,
Flintcreek