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One Cylinder down on Compression

E

evin115

New member
"Hello Everyone,

Greetings

"Hello Everyone,

Greetings ... I am new to the forum and I hope to get assistance from the wealth of talents.

I have recently bought a boat with an Evinrude 115 hp 1977. I took it to the local marine mechanic for a test and tune. He found the the following compression 115, 110, 110 and 90. He told me that it wasn't worth tuning or repairing and to seek another engine. Is this scenario common ? I know some people who says that you can rebuild the engine and it is like new.

Can you give me some advice."
 
"thats a good ol work horse th

"thats a good ol work horse that is usually worth rebuilding.,but is usually cost prohibited......but...it has a lower unit,that is a lil diff...it has a hydro-mechanical,using hydraulic pressure to assist shifting..they wk good,but fewer shops know how,and are,servicing them....u would be better off,getting u a mid 80's or later."
 
I'd run it and see how it

I'd run it and see how it performs. You may be surprised. My old 75HP Johnson has a high of 90psi and a low of 85psi and runs pretty good. Pushes my old Crosby 17ft boat very well.

Decarbon it and the compression may improve or may not.
 
"Thanx Guys for your input.

"Thanx Guys for your input.

Bill Smith ... totally new to fishing and boating, how do I decarbon the engine ?

Thanx.

Steven."
 
"u can get it from a dealer,..

"u can get it from a dealer,..or fr auto parts...
seafoam--goes in fuel tank...cleans as u boat
deep creep,sprayed thru carbs,let sit...run.
all major brands,have thier own de-carbs."
 
"My 1979 Johnson 85HP had very

"My 1979 Johnson 85HP had very low compression (around 50psi on all cylinders). I knew the history of the motor and knew it had been well cared for. I got the Seafoam at WalMart in the Auto section. Squirted some in the cylinders with a small syringe while trying to aim it all around the piston for good coverage (Tilt the motor up for better coverage.) I let it sit for several hours then started the motor. I used a 6 gallon gas can with a full can of Seafoam in it for a fuel source.

Ran it for a little while and rechecked the compression jumped up to 110psi to 115psi. Must of been stuck rings as the motor had sat for several years. My best guess.

Your compression is low on that cylinder but how do you know the gauge is all that accurate? Decarbon and run the motor in the lake before making any decisions on rebuilding. Do remember Seafoam is not a mechanic in a can. It can not fix parts wear or damage. If the motor doesn't perform to suit you then a rebuild is in order.

jwbmarine can help you with that.

Good Luck,
Bill"
 
Steven--- Another "decarbi

Steven--- Another "decarbing"item recommended by my Evinrude dealer Is "Engine Tuner". It's an Evinrude-Johnson product & I paid $8.95 for a can. Be sure to follow the directions on the can.
Bill
 
"Hey Guys,

I am grateful fo

"Hey Guys,

I am grateful for all of your suggestions and advice. I will have to take it one step at a time. First, things first, I shall "Decarbon" the engine and then run another compression test. The aftermath reading will be posted later.

Thanx again guys !

Steven."
 
"de-carbon--items,....have onl

"de-carbon--items,....have only been around for prob 10-15 yrs------prior to that,..there was nothing.....
de-carb---no matter the source--is naptha--napthalene...good stuff.....
now,at every shop,thats worth a d---mn...does a de-carb--during tune up............."
 
you got a 32 year old motor wi

you got a 32 year old motor with a low of 90 on one cylinder....i would decarbon it and run it...check the plug on the low cylinder for fouling and if thats ok and the motor runs decent just run it and enjoy...or sell it while its running and upgrade...reread bill smiths entry also...i would not rebuild an engine that old..
 
"If all else fails, you might

"If all else fails, you might try running it a little rich on oil and see if that helps...maybe 32 to 1...not too much to lose here"
 
"Hey Guys,

Finally got hold

"Hey Guys,

Finally got hold of some de-carbonizing substance. I am based in Melbourne Australia, and it is so damn hard to find the stuff. I called through to many marine stores and ask for "Seafoam" or similar product and they would ask me ... what the item is ? ... then I needed to explain to them. After my 9th call, I finally tracked down a store. I bought it and it was $AUD 25 or $US 17.

I got back so happy but when I proceded to do another test, there seems to be water on the fourth spark plug and the engine idles for a while before dying. What seems to be the problem now ... ?

I did try your trick ... Bob Caskey ( Thanks! ), however I am met with another misfortune, another problem lurks.

Compression reading does differ everytime. 115, 105, 105, 85.

Thanx.

Steven."
 
"pull the hd,where u saw water

"pull the hd,where u saw water.......and i would speculate,that it is w/the sd that has low comp too.prob just bad gasket."
 
agree with jw...i think you sa

agree with jw...i think you saved the motor by looking at plug...i think the compression is too high to have done serious damage....the motor had to be missing and that should be corrected with the water gone...good luck.............
 
"Gasket fixed. Thanx guys.

"Gasket fixed. Thanx guys.

I have installed new coils and fuel filter. I can't seem to turn the engine over. There seems to be oil coming out of the four small tube like, which is in the carb flaps. Not sure what is the problem ...

Can you assist please ... !"
 
"Before you sink a lot of mone

"Before you sink a lot of money in the motor decide if that's what you want to do. To do a rebuild on it would be expensive but no where near as expensive a new motor. Also how long before your government bans 2 cycle engines?

If you rebuild it correctly it will last many, many years if care for properly. Bottom line if you go into this with the understanding that the cost is acceptable to you, go for it. I spend a lot of money on my motors but it is my hobby. I can't learn about them if I don't work on them!!

If you don't have one order an OEM service manual. Mine is very helpful because I don't have the training and experience most of the guys on this forum have!! I envy them!!

First describe what you mean by "won't turn over", i.e. electrically, can't turn flywheel by hand, etc.

If you can't turn it over by hand it is bound up mechanically. Is it in gear? Rule the lower unit out by ensuring it is not bound up instead of the power head.

First I would double check the cylinders. Pull the plugs and look in with a small flash light. Move the pistons up and down and check the tops of them. Of course the best way is to pull the head and do a thorough inspection.

That is an excellent motor to use. The lower unit is very different as JW says but can be repaired if you gather the information and parts. My Dad's is still going strong but he was a fanatic about changing oil and not abusing his motors. Use OMC Premium Blend oil in that lower unit. It is also called OMC Type C oil;
#775609 Premium Blend Lower Unit Gearcase Lube 32 oz.

Read the Joe Reeves post on how to troubleshoot the Hydroelectric shift!!
Clcik on this link:
http://forums.iboats.com/showthread.php?t=105917

Bill"
 
I have just been reminded that

I have just been reminded that the motor being a 1977 is not a Hydro-Electric shift. It's a mechanical shfit motor. Even easier to troubleshoot the lower unit.

Sorry for the confusion.
Bill
 
"Perhaps The head gasket is fa

"Perhaps The head gasket is faulty? Ive ran into that in the past.

Old Johnsons and Evinrudes are a fantastic engine. Everynow and then a real beauty comes along thats been well maintained but because of the age (in your case 77') Its now classed as a vintage. Thats not to say there arent good condition 77' models around.... I think peoples expections of these older engines gets abit unrealistic at times. Im sure youll find another.

Buy a comp gauge and be sure to check the next one your looking at. anything from 110psi and up would be good and a no greater difference than 15% from the lowest and highest reading.

All the best,
Welcome to marineengine!"
 
"Thanx .... Bill Smith and Cal

"Thanx .... Bill Smith and Callum Dicks.

My next step is to take off the lower unit and try to run it again. I will let you know the result.

I understand that this is a old engine ... and is more mechanical than electrical. I also understand that the V4 Evinrudes were well built and considered one of the best in those days. I did have a very old Volvo car (1980's) and it keeps on going.

I have bought a cd ... Evinrude/Johnson Outboard Shop Manual 48 - 235 hp 1973 - 1989, and studying it ... very interesting. Not a lot of components on an outboard compared with a car engine.

I have learnt also about the difference between the marine battery and normal car battery. I will buy a new marine battery ... hopefully a 600.

Thanx again guys ! I'll keep you posted on my (slow) progress and hopefully I'll get the old Evinrude running."
 
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