85 evinrude 25hp power head gasket

[Coy6888]

Bought an 85 evinrude 25hp to play around with as I want to learn more about 2stroke outboards. Got it cheap since the owner knew it needed work he just wasn’t sure what it was. My only outboard exp is spark plugs, lower unit oil and impellers which isn’t t much lol. Previous owner didn’t go into much detail and had no key to the controls. It turns freely but I have not been able to do a compression test yet(just got it and not at shop) When I pulled off the cowel the engine looks great except the entire bottom was covered in black tar like oil. On the underside of the cover where the exaught is also covered in the same sticky black oil. I spent the last hour just cleaning it up and the gasket has chunks missing and falling off as I was wiping with a rag. Before I replace this what should I check to confirm the motor is good besides compression. I obviously don’t want to replace the gasket if the motor itself is no good. I’ll put some pictures, model and ser # below. Also just want to confirm my suspicions like I said being new I’m definitely not 100 percent it’s just what I think. Thanks for any input

 

[oldboat1]

Looks like that motor was sitting in a full test barrel for a season or two -- or something similar. Not sure what gasket was falling apart -- need a head gasket to test compression, which should be a first step.

 

[Coy6888]

I’d say it was def gasket. Can anyone help me out as part as parts or a kit for this? Thanks

 

[racerone]

Just install a new gasket.----And replace the seal on the crankshaft.---Remove seal housing 3 bolts.----Dealer will help with getting you the parts.----First picture is a foam seal and not that important.

 

[Coy6888]

Just install a new gasket.----And replace the seal on the crankshaft.---Remove seal housing 3 bolts.----Dealer will help with getting you the parts.----First picture is a foam seal and not that important.

So you wouldn’t worry about replacing that foam seal? I can’t find it anywhere. Is there just one seal on the crankshaft? Only reason I ask is it doesn’t seem like I would need to remove the housing in order to install a new seal. Thanks so much for the help!

 

[Coy6888]

Also is there anything else I should replace while I have this off?

 

[racerone]

??----It was stated to remove that housing to replace the seal !!

 

[Coy6888]

Update, powerhead gasket on and put back together. New ignition switch, impeller, lower unit oil and carb rebuilt. Compression is 130 psi exactly on both cylinders. Put some fresh gas in it and bam started up first turn of the key and I think its running great for the first time in a few years. Last thing I’m wondering is should I run some seafoam or additive through it since this is the first time it’s ran in years? It’s running so good now I don’t really want to mess with it much more. Thanks!
View attachment FullSizeRender.mov

 

[tphoyt]

Sea foam is some good stuff in my opinion but as the sane goes if it ain’t broke don’t fix it.
Just enjoy it.

 

[Coy6888]

Kind of my thought. Going to throw it on the boat and give it a test drive to see how it does in the water. Thanks!

 

[jasper60103]

Nice job. Good call on the head gasket.
Sounds just like my old 30 hp Johnson.
Darn good motor. Enjoy it.