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Jan 23rd, 2013
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Mercury compression specs??? #12348978
07/20/17 01:37 AM
07/20/17 01:37 AM
Joined: Jun 2016
Posts: 1,071
i-Fish Offline OP
Extreme Angler
i-Fish  Offline OP
Extreme Angler

Joined: Jun 2016
Posts: 1,071
Where in the world can I find compression specs for a 2014 Mercury 150? Testing a motor tomorrow and I ain't got time to buy a manual...


If you can't find em wind em.
Re: Mercury compression specs??? [Re: i-Fish] #12348985
07/20/17 01:40 AM
07/20/17 01:40 AM
Joined: Jun 2016
Posts: 1,071
i-Fish Offline OP
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i-Fish  Offline OP
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Joined: Jun 2016
Posts: 1,071
Or is it just commonly accepted to look for anything over 100 psi and each subsequent piston to be with 10% of each other?

Last edited by HookinToads; 07/20/17 01:40 AM.

If you can't find em wind em.
Re: Mercury compression specs??? [Re: i-Fish] #12349121
07/20/17 02:25 AM
07/20/17 02:25 AM
Joined: Dec 2008
Posts: 7,328
Boerne, Texas
G
grout-scout Online content
TFF Celebrity
grout-scout  Online Content
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G

Joined: Dec 2008
Posts: 7,328
Boerne, Texas
You have to test compression on mercs in a very particular way. You can't just stick a gauge on them and get an accurate reading.

Re: Mercury compression specs??? [Re: i-Fish] #12349254
07/20/17 03:38 AM
07/20/17 03:38 AM
Joined: May 2003
Posts: 11,494
Littlefield Tx & Lake A. H. US...
gary purdy Offline
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gary purdy  Offline
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Joined: May 2003
Posts: 11,494
Littlefield Tx & Lake A. H. US...
A leakdown test is the only true test of a cylinders condition. A simple sparkplug out cranking speed compression test is a starting place, then check each cylinder at full throttle, then leak test, if an abnormality is found then bore scope.


The world will not be destroyed by those who do evil, but by those who watch them without doing anything. Remember what He has done and remember that He is not done yet!-- GOD IS GOOD
Re: Mercury compression specs??? [Re: i-Fish] #12349484
07/20/17 12:57 PM
07/20/17 12:57 PM
Joined: Dec 2014
Posts: 1,664
Euless
M
Muzzlebrake Offline
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Muzzlebrake  Offline
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Euless
Cranking compression will be different between 2 strokes and 4 stroke engines.
Ballpark, you might see 120 on a 2s and as much as 175 on a 4s.


From Genesis: "And God promised men that good and obedient wives would be found in all corners of the earth."

Then He made the earth round...and He laughed and laughed and laughed!

Re: Mercury compression specs??? [Re: Muzzlebrake] #12349561
07/20/17 01:47 PM
07/20/17 01:47 PM
Joined: Feb 2007
Posts: 542
Lake Fork, Texas
Rick Collis Offline
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Rick Collis  Offline
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Joined: Feb 2007
Posts: 542
Lake Fork, Texas
It depends on how you take the compression. There are several methods. The best engine I ever owned was a 225 Optimax. It had between 90 and a 105 lbs compression shortly after it was brand new. It is still running great with over 1700 hrs. So don't get too carried away with numbers. As already stated all cylinders should be fairly close.


Rick Collis
903-473-8820
Re: Mercury compression specs??? [Re: i-Fish] #12384320
08/13/17 03:57 PM
08/13/17 03:57 PM
Joined: Nov 2002
Posts: 3,738
Yantis, TX
Gamblinman Online content
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Gamblinman  Online Content
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Joined: Nov 2002
Posts: 3,738
Yantis, TX
Motor hot, kill switch pulled, throttle wide open, All plugs removed...test each cylinder. You should be looking more for a wide variance between cylinder pressures.

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