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Rebuild or no rebuild that is the question

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axiom

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what compresion range is good

what compresion range is good on a 1996 ocean pro 200hp. Mine is 95ls. I wondering if i should rebuild
 
"Just curious guys, but if com

"Just curious guys, but if comp is low say 95 psi all round , but consistant, why is that better then say 105 106 102 and 95 on a 4 cyl? why is the low comp better then higher less consistant comp ? as you can tell not much grease on these hands, maybe a little but not much."
 
a high difference in compressi

a high difference in compression will throw the motor out of balance causing high fuel consumption and poor performance.....and could lead to an internal break down and come apart.

if your comp is within 10-15% of each other you are ok within 10% is ideal.
 
"compression should not vary m

"compression should not vary more than 10% between cylenders, not sure about the newer models,but that is not a bad reading they are all
constant.
I would just run it till it dies."
 
"Brian, I would expect at new

"Brian, I would expect at new motor to have compression in the range of 120-130.

However, most compression gauges are not calibrated all that well. I have two of them and neither one will give the same reading on the same cylinder - sometimes the disparity is in excess of 25 psi.

As has been noted above, as long as all your cylinders are within about 10% of each other, the motor is probably fine.

In general, I would look for around 100 psi - and yes, yours sounds fine - would suspect the gauge is reading a little low.

If you still have a concern, I would take it into any shop that can perform a "leak down" test. That will determine how long it's holding it's compression. If that number is good, no worries. If it's low, a new set of rings may be in order..."
 
"graham,those loopers never pu

"graham,those loopers never put out that high of comp ,even right outa the box....105-110 is as high as i've ever seen them.
brian,as the other guys have said,..as long as you've got fairly even comp,...run it.....my 97 200 has about 100 or just under on 5,and 1 has about 95...
a yearly DE-CARB will help keep your eng in good shape,and clean internally,if done right.
STUCK rings,due to carbon build up,is a major reason,as well as carbon UNDER the rings,causing ring to catch ports,..and SNAP......"
 
Thanx guys i was thinking that

Thanx guys i was thinking that this motors comp wasent that high when new i think i'm going to run it and see what happens. I run another boat for fishing and this boat was only going to get used very little each summer about 20 or 30 hours each year. I guess i'l run it and if i have problems then i can rebuild. I'll get it in during the spring and get the carbs cleaned or rebuilt. Thanx again for all your imput . Brian
 
I read somewhere that between

I read somewhere that between late 90s and early 2000s Evenrude/Johnson made their engines "low compression" to accommodate for their use with low octane gas... how true that is I’m not sure… I think some engines came @ 90psi from the factory
 
"in all the years,i un-boxed a

"in all the years,i un-boxed and rigged new eng's of every size,..i dont recall ever having to run a compression test on one,unless,it had a problem,say at the 20 hr ck.....the 80's crossflows were in the upper 90's to 100 or so,so w/many yrs,could wear down to 85 and run ok,except a lil doggy outa the hole,due to less torque.the 70's ,75 hp's--would put out 150 or so,consistently....i have seen the crossflows v4 v6 that were overhauled,crank up around 110."
 
"somewhere over 100...prob aro

"somewhere over 100...prob around 105--110 maybe..ea eng,can be diff,depending on oils,break-in,how used,etc."
 
"The main thing is to decarbon

"The main thing is to decarbon it every year. I didn't know that and am going to have to pay dearly for it. I have a 1990 Johnson 150 GT that won't idle very good at all. I have got leak by in the 1,3,& 5 cylinders. I have run fuel additives, have decarboned twice in 6 weeks and no change. I will have to rebuild it to make it right. All electrical and carbs have been replaced. But it is still cheaper than a new motor. Like I said, decarbon every year."
 
"hey richard,....chg the recir

"hey richard,....chg the recirculation valves...that can drastically improve idle...they r about 23 dlrs a piece...might evenchg hses,r at least,blow thru them...makes a diff,..but may not even be noticable,but the eng will know.,and it does,help at times...esp if they r original."
 
"carbs,idle circuits,..have to

"carbs,idle circuits,..have to be perfect...chrystal clear/clean,sealed..etc...make sure primer hoses are not cracked,sucking air etc...best,...repl all hoses,primer/recirc,and valves."
 
Thanks for the info JW. I wil

Thanks for the info JW. I will check that stuff out. Sure would be nice if that was the cure.
 
"JW I checked out my Climer ma

"JW I checked out my Climer manual and some other parts sheets I have and couldn't find anything about a recirculation valve. I am guessing you are talking about OMC part # 0392988 refered to as a check valve and filter. There are 6 of them, one for each cylinder. It looks like they mount in the intake manifold under the carb base. I changed the oil / fuel pump out about 4-5 years ago and put new hoses on all that system and I am thinking that when I put kits in the carbs, I put new hoses on that system too. I didn't however put the small hoses on that run to the top of each carb. I just checked them and they seem to be in good condition."
 
"clymer,& seloc,...leave a

"clymer,& seloc,...leave alot to be desired...to say the least,(and politely).........................u r correct,...chg them OUT....YOU may not notice it,but the ENG WILL..."
 
"Thanks JW, I will get to that

"Thanks JW, I will get to that as quick as I can. I don't have a heated shop, so it has to be around 60 before I can tackle it. I hate to pick up a cold wrench!! My old Arthritus will let me know if I do. I know what you mean about the Clymer and Seloc. I think Clymer is better than the other. I had a seloc and just trashed it! I do however have some original parts sheets and exploded diagrams that are factory. A geat parts lady printed them off for me. They are sure nice to refer to."
 
i chged them out of my 97 200

i chged them out of my 97 200 last summer.4 out of 6 were bad..i've had the eng 1.5 yrs.
 
"I am sure hoping that those c

"I am sure hoping that those check valves will do the trick for mine. It has just gotten worse about the last 5-6 years. Makes it hard to load on the trailer. Have to idle it at about 1,000 to 1,100 RPM and I cringe everytime I drop it in gear. If I would keep using it like it is, sooner or later it would damage the lower unit."
 
"well,..u r a lil too far fr m

"well,..u r a lil too far fr me...but,....if u wanna mess w/it...we can get it right....on here...
at that rpm richard,u r gonna knock a tooth off a gear...."
 
I was looking at other motors

I was looking at other motors like mine for sale they were stating 120 to 130psi how is this possibe if you guys are saying these motors had 105 to 110psi when new. Can anyone explain Thanx Brian
 
"Brian, I have two different c

"Brian, I have two different compression gauges. On my 1986, 140 Ev one of them gives me about 100 psi each cylinder and the other gives me about 85 each cylinder.

Which is correct? probably neither, but that doesn't matter, because all the cylinders are fairly balanced and unless you have a very high end gauge that you have calibrated regularly then they are going to give you a bogus reading.

If I'm trying to sell you something and I heard somewhere that the spec is say 120, maybe I would say all had compression of 120 if I was a little dishonest or was trying to make the motor sound good.

If one cylinder is reading 30 or 40 pounds lighter than the rest, there's a problem....

I have numerous factory service manuals for Merc, OMC, Honda and Yamaha. On most models they don't even list a factory spec for the compression (although they list the proceedure to test compression) - so either an oversight or something that the engineers didn't think was overly important.

On 90 percent of the motors out there, anything greater than 90 psi is generally "decent".

If you really have concerns, a leakdown test is far more accurate in detecting an issue. It will tell you (more importantly than a single number for compression), how well that cylinder is holding it's compression.

A teaspoon of oil in a cylinder will give you a good compression reading even if it's shot - a leakdown test will look past that "magic trick"..."
 
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