Compression test ok??

[Zack19919853]

Ok, I have a 1990 Evinrude 88 SPL. I did a compression check on it and cylinder #1 checked in at 110, cylinder #4 checked 105, cylinder 3 checked in at 105, and finally 2 check in at 95.. is number 2 being at 95 ok? At first it was at 105 I bleed the gauge and redid it at 95 psi.. what do y’all think I know they are all supposed to be within 10% of each other correct. I have been having issues with fuel delivery, being that there is water in fuel tank. I dropped it. Going to clean it out. Going to clean carbs with chem dip my favorite. Love that stuff and fire her up hopefully my compression is up to par?? Thank y’all

 

[racerone]

Pull the bypass cover on # 2 cylinder.----Just 6 wee screws and a $2.00 gasket.-----Lets you inspect piston / rings.----Or pull the port side cylinder head.----This sound like possible expensive repairs are needed.

 

[Zack19919853]

Racerone maybe the gasket on the by pass is whet what you may think it might be? Or rings?

 

[racerone]

Sorry----- the gasket on the bypass cover has nothing to do with compression in the cylinder.----And before you ask, the reed valves have nothing to do with compression in the cylinder !!----Piston rings are often broken on these motors !----All easy to check out.

 

[Bosunsmate]

If it runs to what you need dont worry about compression. You can use some ring freeing fluid, try seafoam etc if you really want but sometimes if they are stuck they are snapped and you dont want them coming loooose

 

[Zack19919853]

Thank you both for the information. Definitely will take a look just to see. I have taken the heads off as I have had to replace the deflectors everything looked ok.. I felt the cylinder walls and the all were smooth no scratches

 

[Bosunsmate]

Sounds good.
I recommend planing heads before reinstalling. All you do is get a bit of glass or a mirror. cover it in very fine grit sandpaper and move the head around it in a figure 8 pattern until the whole underneath is shiny indicating youve got all the high/low spots evened out. Ive never had a motor that didnt benefit from that. The mirror etc is a perfectly flat surface hence why i use that.
Make sure you retorque after the first heat up cool down cycle too

 

[racerone]

Remove bypass cover and inspect piston and rings on the cylinder with 95 PSI.----Will tell / teach you a lot.---Costs say $2.00 for a gasket to install it again.

 

[Zack19919853]

Definitely will do that racerone! I will check the piston and ring on number two. I have to order a gasket from Evinrude. And good to know bosunsmate. I did use like 200 grit for the heads to get old gasket material off.. never though of a mirror that’s a great idea! I’ll order gaskets for the covers and heads and the bypass cover. Also I cleaned carbs and now they both flood The first prime didn’t.. I had to basically bottle feed it by squeezing gas in the cylinders. To basically prime it.. I’m think float bowls stuck open?? But after cleaning why the stuck open? Ugh frustrating lol

 

[Zack19919853]

Well now that I took them both off. I blew in the right side up then turned the upside down and they sealed... idk why it would flood when I was priming the bulb..

 

[Zack19919853]

Just so everyone knows lol it was the float bowl gasket leaking.

 

[Bosunsmate]

Great, dont worry about compression if she runs fine.