1999 Johnson 90 HP Ocean Pro outboard. No compression. 90,90,89, 0. Help!

[ojt23]

Hello, just bought a 1995 Stratos 178 bass boat with a 1999 Johnson 90HP OceanPro #J90SPLSSC. I bought it for hull price, since I knew the engine was going to be a possible rebuild / scrap. Plus came with lots of cool stuff, 70# trolling motor, 2 newer Lowrance Fish finders/GPS, fishing gear, etc.

I've perused the forums and got a lot of good info, however, I thought I would get more accurate info if I posted my situation.

Anyway, the previous owner said he bought it without a compression test and during his first outing the motor ran great for 2 hours then died. VRO is disconnected, using 50-1 premixed fuel. No alarm, no high temp. Because of this, I thought I might be looking at a blown head gasket if I was lucky. For the price, I figured I could repower / rebuild and still be okay.

I did a compression test when I got home. 90,90, 70, 0. From what I know, these are low compression engines by design, so 80-100 should be good. So I removed the head-it was pristine, and looked in the cylinder, which had no scoring and looked perfectly fine with a bit of black carbon buildup, then sanded down the head with 800 grit, put new O-rings and thermostat seal in, put RTV seal on the head for the water jackets, and reassembled. Torqued head to 22 fp per manual. The old O-rings were cracked and flattened, so I got really excited about an easy fix. That excitement was short lived....the compression was now 90,90,89, 0. Some improvement on #3, but nothing on #4. Damn! I figured stuck piston rings, right? I took it apart again, put PB blaster around the cylinder and got it up to about 30, then back to 0. Stuck rings, I'm sure now, right? Anything I'm missing? I'm confident the gasket is sealing well, tried 2 gaskets, but even if it was leaking, I would get SOME compression. Doesn't appear to be warped at all. Piston is tight against cylinder walls. I tried to clean the pistons a bit with some scotch brite pads, but figured I'd better solve the big problem first. See pictures.

Should I try some ATF in the cylinder or is this a rebuild for sure? Any other suggestions? I don't have the time to rebuild, and don't want to attempt it. I really want to exhaust all means I can to try to fix it. The engine starts and runs ok, so should I just run at idle for awhile using a water bucket and try ATF / Marvel Mystery Oil / ANYTHING else, or anything else to try to get these unstuck?

Now, I found two 2006 Honda 90hp outboards, just rebuilt for a great deal. I can have one for a backup or resell. Of course, I will check these out thoroughly. Anyone know about these motors? Can I use the Johnson controls?

How much is this motor worth if I decide to sell it as is with controls

I don't need fast, just reliable. My wife, 3 kids and I just want to go fishing.

Thanks in advance for any responses. Love this forum so far!

 

[hosteter]

What about piston rings?

 

[phillnjack2]

turn flywheel so the piston rings can get a sort of seal without fluid dispaearing and pour in some deep creep / seafoam / engine tuner and leave it over night. if you have carbon on the rings they simply wont just come unstuck . the bit where you got 30 psi was they moved a bit then jammed up again.. i would definitely be putting in some thing to clean the carbon off the rings before going made with it.
you can leave the head on if you want, just make sure there is plenty of stuff getting to the rings to free off the carbon.. i think its sticky rings or a snapped ring !!

 

[ojt23]

Thanks guys. Picked up some Marvel Mystery Oil during lunch. Next will be seafoam and deep creep. Hopefully they got a little loose over the last 24 hours with that PB Blaster. Crossing my fingers....

 

[Faztbullet]

1) is piston moving when flywheel rotated?

 

[ojt23]

1) is piston moving when flywheel rotated?

Good question, it moves when I hit the starter. Haven't turned it with the flywheel. I also figured it would be making a heluva racket if the connection rod had snapped.
One question, the head is on so I can't check right now, but has anyone ever tried to move the piston to a position where the exhaust port is just becoming visible then use a awl in the shape of a hook to try to move the piston rings? It would be great if the gap for the rings was right there!
Thanks!

 

[racerone]

????-----You will not find ring gaps at the ports !---And rings are pinned so they can not rotate !--Mechanic in a can will not likely fix this.----Me thinks motor has to come apart.

 

[ojt23]

I tried putting the Marvel Mystery Oil in the plug holes with the piston at the top of the cylinder and left it overnight twice. Starts and runs okay, but no improvement on compression. It gets to about 15 psi. Is this progress? Should I keep going at it?

I'm looking at replacing it with a 1996 Nissan 90 HP motor with gauges and controls. It was recently rebuilt, 130 psi on all cylinders. I feel much more confident in swapping out the motors than rebuilding the Johnson, but does anyone have experience swapping them out? Nissan/Tohatsu manuals are available free of charge on their website (whats up with that, Johnson/Evinrude?), and those may help. I will probably need a crane and a place to mount the engine once it's off.

Also, if I sell it as is, what do you think I can get for the 90 Johnson as-is? I think it has about 500 hours on it or so.

 

[bob johnson]

from the looks of the head and what can be seen of the walls....you haven't LOST a ring....so there might not be any damage... so you may only have to pull it apart and put new rings in the one hole......maybe even just clean up what you have and reinstall..... no parts but some gaskets....

I cant see anyone paying more than$700 for a motor with 0 compression in one cylinder.....even though the parts are worth more....

if you are not mechanically inclined or have the tools....buying the other motor might be easier for you......


PS does it look like the o ring seal against the block is asymmetrical???????.... to anyone else??

bob

 

[ojt23]

Thanks Bob! Great points. I guess I didn't notice the head looking a bit funny. Not sure if that's an illusion or not. I don't think it warped but even it it was slightly warped, wouldn't the o rings seal it tightly enough?

Also, seems like it would have had to been incredibly hot to warp it that way. I sanded it down but maybe I should have a machine shop take a thousandth off to ensure it's flat as a pancake.

Does anyone think there's a chance the head itself is cracked?

700 is not too bad. I'll let you know how it plays out.

 

[ojt23]

Thanks Bob! Great points. I guess I didn't notice the head looking a bit funny. Not sure if that's an illusion or not. I don't think it warped but even it it was slightly warped, wouldn't the o rings seal it tightly enough?

Also, seems like it would have had to been incredibly hot to warp it that way. I sanded it down but maybe I should have a machine shop take a thousandth off to ensure it's flat as a pancake.

Does anyone think there's a chance the head itself is cracked?

700 is not too bad. I'll let you know how it plays out.

 

[ojt23]

Picked up the Nissan 90 outboard. Going to swap it in a couple of weeks. Anyone interested in a 1999 Johnson 90 Ocean Pro?