Is There an Evinrude Mechanic In The House

M

MarkSr

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Jan 5, 2010
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15
I've asked this question before but I get so many different answers.Is there a mechanic for outboards that can answer this question.I'm looking at a boat with a 98/225hp evinrude.I'm am concern about compression.Is there a true answer about compression for this motor.Whats the min. psi it can be before rebuilding? Thanks in advance.

Mark Sr
 
JB

JB

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Re: Is There an Evinrude Mechanic In The House

Howdy.

Welcome to iboats. :)

No, Mark. There is no minimum number of psi specified because there are too many variables in the measurement process.

Big OMC V6s typically compress 80psi or more, which is lower than many other models, but individual examples might give you 125psi.

I am sure that I am not the first to tell you that all 6 must compress within 10% of each other and it is that spread that tells you about the engine's health.

I have never, in 60 years of messing with outboards, seen one wear out. I have seen thousands in which one or two cylinders lose compression due to a failure of some sort, or excess carbon buildup. Those are the engines that need rebuild. . .broke engines, not worn out engines.

Good luck. :)
 
junior1113

junior1113

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Re: Is There an Evinrude Mechanic In The House

my 93 200 is in the lower 90 psi range. (same 3.0 looper) it runs great. u will notice that bottom cylinders are 5 psi lower than top 2. which is normal on these motors. they are torque monsters and love gas and rpms i run 5900 wot.
 
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jonesg

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Re: Is There an Evinrude Mechanic In The House

1994 150hp , 83-85 psi on all six and it runs strong.
 
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daselbee

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Re: Is There an Evinrude Mechanic In The House

1998 225 3.0 looper, 100 psi on all six.

1996 200 3.0 looper, 110 psi on all six.
 
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seahorse5

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Re: Is There an Evinrude Mechanic In The House

Depending on the strength and condition of your starter and battery, plus the accuracy of your compression gauge, the average compression is around 100 psi or so. You are really just looking for the numbers to be fairly close to each other.

For best accuracy, perform a decarbonizing procedure first using the Evinrude Engine Tuner and follow the directions on the can.

You want all the cylinders to be within 15% of each other and you may notice that the bottom two cylinders, #5 and #6, may be about 5# lower than the others, which is normal.
 
Joe Reeves

Joe Reeves

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Re: Is There an Evinrude Mechanic In The House

Thru the years since the loop charged engines came into existence (the 225hp included), I've always found that the starboard bank would be slightly higher than the port bank. The average compression (even on new engines) would be 95 psi on the starboard bank and approximately 90 psi on the port bank, no lower than 90 psi. The difference being due to the engine's design.
 
86 century

86 century

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Re: Is There an Evinrude Mechanic In The House

May not be any help but my '77 200hp cross flow has 80psi on two bad pistons(burnt with parts missing). It runs good and pulls like a monster. good luck
 
Gary H NC

Gary H NC

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Re: Is There an Evinrude Mechanic In The House

My original V-6 175 cross flow has never been rebuilt and reads 90 to 93 on every cylinder.
I think if the carbs are kept in good shape and a decarb done once a year mine will run another 20 some years...They are tough motors..;)
 
M

MarkSr

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Jan 5, 2010
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Re: Is There an Evinrude Mechanic In The House

Thanks for all the replies.I have one more question.
What's a 3.0 loop engine


Mark Sr
 
JB

JB

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Re: Is There an Evinrude Mechanic In The House

MarkSr said:
Thanks for all the replies.I have one more question.
What's a 3.0 loop engine


Mark Sr
Click to expand...

3 Liters displacement, loop scavenged.

"Loopers" use a flat top piston and intake ports on the sides of the cylinders. The name comes from the flow of the intake charge doing a loop to scavenge the cylinder.

Loopers are generally superior to cross scavenged engines in torque, output per displacement, efficiency and emissions.

The first OMC loopers were the two and three cylinder 40-70HP outboards introduced in the late 60s. The V4 and V6 engines switched over beginning in the 80s.
 
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BigB9000

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Re: Is There an Evinrude Mechanic In The House

No real help but;

1983 115hp

90 91
87 60



Runs amazing.
 
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