83 Johnson 7.5hp hates its cover

Lee5267

Cadet
Joined
May 20, 2003
Messages
19
Does anyone have any idea why my motor will run great with the head cover off as opposed to it being on. It doesnt appear to be rubbing the inside of the engine cover anywhere with the fly wheel or anything else. As soon as you put the head cover on there is very sluggish acceleration and max RPMS drop about 1-2000.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: 83 Johnson 7.5hp hates its cover

look for an exhaust leak in the area where the powerhead meets the leg.
 

Lee5267

Cadet
Joined
May 20, 2003
Messages
19
Re: 83 Johnson 7.5hp hates its cover

I just had almost the entire motor apart to replace a rubber gromet where the water tube meets the head. Everything went back together well and seems to seal well too. How should I check for a leak. I can see quite a bit of oily residue around where the leg meets the head.
 
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