cowl air inlet on mercury 9.9.

billhig

Cadet
Joined
Apr 27, 2025
Messages
16
I've got a 1979 9.9 2 stroke and I don't see where the air inlet into the cowl is. The top cowl is completely sealed and the only gap in the lower cowl is a finder width opening around the shift shaft. It doesn't look very big. Am I missing something obvious?
 

airshot

Vice Admiral
Joined
Jul 22, 2008
Messages
5,786
Usually in the rear of the cover, made to be a lift handle for tilting the motor.
They also act as an air opening if you look carefully.
 

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
8,226
It is in the rear of the cowl by the grab handle. Or are you saying it does not run with the hood on?
 

billhig

Cadet
Joined
Apr 27, 2025
Messages
16
It is in the rear of the cowl by the grab handle. Or are you saying it does not run with the hood on?
It runs poory at WOT with the cowl on. It runs smoother and goes faster with it off. I have read that can be caused by an exhaust leak so I just pulled the powerhead and replaced the exhaust gasket. TBD if it helps.
The cowl is completely sealed at the grab handle by the part shown in the pics. The hole in the front of the cowl is sealed by the rubber piece around the starter pull. The only opening is down by where the shift shaft comes in but that's pretty small.
 

Attachments

  • 20250819_153049.jpg
    20250819_153049.jpg
    2 MB · Views: 5
  • 20250819_153016.jpg
    20250819_153016.jpg
    2.4 MB · Views: 5
  • 20250819_160419.jpg
    20250819_160419.jpg
    1.5 MB · Views: 5
  • 20250819_160429.jpg
    20250819_160429.jpg
    1.6 MB · Views: 4

cyclops222

Commander
Joined
Mar 21, 2024
Messages
2,726
My old Evinrudes look like they have no breathing opening. They have gaps around the bottom of the cowling to keep water & spray out of engine parts.
 

airshot

Vice Admiral
Joined
Jul 22, 2008
Messages
5,786
Where the grab handle is located, there should be an intake up near the top so water can't get in. Can be hard to see, check for wasp/bees nests there. Blow air up into the area and you should feel air moving. It could be possible that it became blocked somehow, but that is where all have been in my outboards.
 

billhig

Cadet
Joined
Apr 27, 2025
Messages
16
Where the grab handle is located, there should be an intake up near the top so water can't get in. Can be hard to see, check for wasp/bees nests there. Blow air up into the area and you should feel air moving. It could be possible that it became blocked somehow, but that is where all have been in my outboa

Where the grab handle is located, there should be an intake up near the top so water can't get in. Can be hard to see, check for wasp/bees nests there. Blow air up into the area and you should feel air moving. It could be possible that it became blocked somehow, but that is where all have been in my outboards.
As shown in the pics, the grab handle is completely sealed. That's why I'm confused.
 

cyclops222

Commander
Joined
Mar 21, 2024
Messages
2,726
Well I am feeling great with my medical cup of Caffeine. So I will go to the boat and see if there is a removable part in the cowl / cover. Take it out. 2 strokes are noisey already.

NAAAAH It is a fantastic reliable engine since 1986. I will respect it's age and retirement duty.
If it is not broken. I will not fix it.
 

billhig

Cadet
Joined
Apr 27, 2025
Messages
16
Well I am feeling great with my medical cup of Caffeine. So I will go to the boat and see if there is a removable part in the cowl / cover. Take it out. 2 strokes are noisey already.

NAAAAH It is a fantastic reliable engine since 1986. I will respect it's age and retirement duty.
If it is not broken. I will not fix it.
Great minds think alike - I took out the grab handle insert and now I've got a huge inlet. I'm still confused as to why there is none to begin with but that's a reasonable solution. However, that had no impact on the boat running poorly at WOT with the cowl on.
 

billhig

Cadet
Joined
Apr 27, 2025
Messages
16
Exhaust leaks are often caused by the powerhead base gasket.
Yes, I knew that. I replaced the gasket from the powerhead to the adapter plate and the gasket from the adapter plate to the mid-section. Still acts the same. I'm running out of ideas but I'm gonna change out the plug wires as they get close to the cowl. they are probably 20 years old.
 
Top