Compression question on 2004 Mercury 9.9 EXLH

hz

Seaman
Joined
Jul 24, 2007
Messages
62
I'm about to buy a 2004 Mercury 9.9 EXLH for my boat. I'm told compression is 190 and 160. Anything to worry about?

I'm also told that Tohatsu makes the 4 stroke Mercury. Is that true?

Harris
 

Star

Chief Petty Officer
Joined
Sep 21, 2010
Messages
481
Re: Compression question on 2004 Mercury 9.9 EXLH

I have owned a used 05 Mercury 15hp made by tohatsu for 4 years. when I got it ti didn't run well found that the head wasleaking across the cylinders. I ground the head and put in a new gasket. A shop would have gotten $200 plus to do it. After the gasket and a carb rebuild it runs like a champ. Great on fuel and pushes my 61 14' Starcraft Tiny tinny tank over21 mph. That 9.9 block is used out to 18 hp acordin to
the Tohatsu Geru on the Hond /Tohatsu threads. Great on gas.
 

Star

Chief Petty Officer
Joined
Sep 21, 2010
Messages
481
Re: Compression question on 2004 Mercury 9.9 EXLH

Sorry I didn't tell you the compression test on mine is 175# and 170#. I would look for a tight valve adjuster. If you have 190 # on one cylinder the other shouldn't be so different with a motor of this quality.
By the way if this is not an electric start there is an unloader that has to be disabled before you can get a reading, it would show 50 or 60 pounds otherwise. I believe this difference will definatly cause problems for you.
 
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