What should the compression be?

Joined
May 24, 2010
Messages
21
Just curious what the compression should be on my 98 evinrude 3 cylinder. I bought a comp gauge today and it says I am getting exactly 100 on each cylinder. Is this normal.. Also another question, what is the air valve on the left side of the motor for, looks like a valve stem..Thanks in advance!
Jim
 

Bifflefan

Commander
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May 27, 2009
Messages
2,933
Re: What should the compression be?

Compression sounds fine,

the valve, i have no idea. Pics are needed here.
 
Joined
May 24, 2010
Messages
21
Re: What should the compression be?

Ok glad to hear my compression is good. The valve is an air fill or release valve, Its right behind the carbs. Looks just like a valve stem on a tire. I figured maybe its some sort of vacuum system, but I know nothing about this motor.
Thanks
 

AlanR

Petty Officer 1st Class
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Jul 14, 2006
Messages
310
Re: What should the compression be?

Pictures, Pictures, Pictures PLEASE

we should be able to tell you what it is then

Compression sounds good by the way
 
Joined
May 24, 2010
Messages
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Re: What should the compression be?

Its right behind the middle carb. Thanks
 

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BigB9000

Lieutenant Junior Grade
Joined
Dec 5, 2007
Messages
1,154
Re: What should the compression be?

the fitting is probably for this stuff:

engineTuner_FULL.jpg


Johnson Evinrude OMC Engine Tuner

(tune up - in a can)
I have a can of it in the garage. The newer engines have that fitting and the tube screws right in, with my (old) engines, I just cut the end off.
 
Joined
May 24, 2010
Messages
21
Re: What should the compression be?

Ok cool...Is that for decarbing? Or is it better to get the other stuff like seafoam deep creep etc.
 

wilde1j

Vice Admiral
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Apr 15, 2002
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5,964
Re: What should the compression be?

Deep Creep is Sea Foam in a pressurized can and both are the same as Engine Tuner.
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: What should the compression be?

Deep creep also fits the schrader valve adapter as does the aerosol fogging oil. All of them require the injector hose, part # 0763644. http://shop.evinrude.com/product/0/763644/_/Injector_Valve_and_Hose_Assembly

SeaFoam and DeepCreep are very different formulation from BRP Engine Tuner, check the MSDS.

http://www.ishopmarine.com/ishop-catalog/msdscat/BRP/Data_Sheets_PDFs/777188.pdf

http://www.seafoamsales.com/component/option,com_rokdownloads/id,272/task,download/view,file/
 

wilde1j

Vice Admiral
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Re: What should the compression be?

Never checked the safety data, but the stuff all smells the same and does the same job.
 

ezeke

Supreme Mariner
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Sep 19, 2003
Messages
12,532
Re: What should the compression be?

Never checked the safety data, but the stuff all smells the same and does the same job.

Well, I posted the links, you read em and tell me how they are anything alike.
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: What should the compression be?

They, in fact are not that very different. The Valspar (BRP) product) MSDS has considerably more detail, especially for the trace compunds, but the bulk of both are naptha or very close relatives of naptha. Pale Oil is a naptha compound, which makes up the bulk of Sea Foam. Water is primary compound by volume lacking in the BRP stuff, while Sea Foam has IPA (Isopropanol), an alcohol, which is not present in the BRP stuff, in about equal amounts, although the BRP stuff does have a small amount of several different hydrocarbon alcohols.

The real point is they both do the same job. I've used both, as well as the Mercury compund and they all work about the same.
 
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