Okay, I was having some problems keeping the engine running about 1100 rpm's. Initially I was thinking the carbs, but I wanted to do a compression and spark test first. Ran the compression last night. On an '84 Evinrude 90hp, I got 115, 120, 30, and 115. Ouch!!!

Just looking for anyone's advice on what to do. The boat and motor are only worth about $1800 blue book, maybe would have fetched $2500 rigged up if it was running well. I've had it for 6 years with minimal problems and didn't pay that much to begin with (under $4k). Was a good boat to learn on.

My first reaction is to walk away. I'd love to get a new boat anyway. With the silly culvert splitting our lake, I'm limited to 85 or 86" max beam. My lead candidates are the Lund 1775 Classic SS or 1600 Explorer SS.

I could possibly re-rig with a new or slightly used motor. Figure another 90 horse will run at least $6 or 7k. Anyone know how much it costs to have some remove the old motor and re-rig a new one? Although I love this boat, the carpeting and exterior are not at all in pristine condition. It's a 1991 Forester V165 with a 76" beam, worth ony maybe $1k.

Or I have a neighbor who works on engines and is quite handy. I think it's entirely possible that he could rebuild the bad cylinder. My main problem with that is I don't know what caused this problem in the first place. Faulty VRO? It was an '84, the first year for this option. Plugged carbs that leaned out a cylinder? Some particulates in the oil injection? I'm a little nervous to throw any money at this thing.

Any advice at all is welcome. I knew this day was coming, but was hoping to get a few more years out of her.

REBUILD POWERHEAD AND DISABLE VRO AND MIX YOUR GAS. This will cost you the least up front and will probably buy you another 10 years on that rig at least.

I somewhat agree with overdalimit. First however, I would try and figure out why the one cylinder is so low compared to the others.

Sometime a head gasket will do this. Making one cylinder leak out. Repair if you do yourself is a measley 35 bucks or so.

Either way you need to remove the head. Very simple to do on this motor. Take it off and take a peek at the pistons and cylinder walls. My personal experience with a very similar motor is that if there is piston damage it will be somewhat obvious with a simple visual inspection. If there is no damage it's very possible just a gasket. Tough to tell from this end of the keyboard but low compression in only one cylinder isn't necessarily the end of the motor, although it could be.

If there is serious cylinder or piston damage then I would rebuild the powerhead. I'm running a rebuilt powerhead on my 87 Johnson and it's running like the day it came off the factory line now.

Compression can be a hard thing to nail down, what caused it anyway.

If your real lucky it could be a head gasket or stuck ring.
If it were mine heres what I'd do. In a remote gas tank mix one can of sea foam to one gallon of gas. With muffs on run the outboard at idle for a half hour. Next pull the plug, tilt outboard up and fill cylinder with penetrating oil, let it soak for a few days. Tilt outboard back down, put the muffs on. With plug out turn the outboard over till the p-oil is blown out. Replace the plug and start, let idle till the remainder of gas in gallon can is gone. Let it cool down and check compression again.

If that didn't do anything then you have nothing to lose by taking it off head and inspecting the gasket for a leak.

If that all checks out then you have a decision to make.

Have it rebuilt, get rid of it, or part it out.

I have a friend that had the same outboard and had to make the same decision. The oil line was brittle and cracked when the outboard was tilted up. That was the reason for failure. You'll need to find out why yours lost a cylinder. Since a new outboard wasn't in the budget and considering it was in the Fall and he didn't need it till next year, I recommended he have the outboard rebuilt. Now when I hear of someone having a rebuilt engine I'm skeptical as to what was replaced. This was a total rebuild not just a fix.
The guy did a very good job but come that Fall during winterization the owner didn't fill the lower unit after draining it.
Long story short, hes looking for a lower unit. For now he bought a 1979 85 hp Rude to get him by.

Since we have a lot of open water season left the fastest way to get back on it would be get a used outboard. Considering the year of your boat I wouldn't put a new motor on it for the reason if you ever sell it you'll never get that back. For the price of that new outboard you could get a used rig thats updated quite a bit from what you have now. If you can hold off then getting yours rebuilt by a good mechanic might be the best thing to do.
Your looking at $1000-$1500 to have that done.

Using a de-carboning product like Engine Tuner would be another option. Run the engine on the muffs to warm it up, remove the front cover of the air box, at a little more than idle spray the engine tuner into the carb throat until you get 'er good and smokey. shut engine off and let it sit for an hour or so. Start back up and get it up to temp, shut down and let it cool down, check compression.
If you still have low compression on that cyl, then ST probably summed it up best. I just delivered the news to someone late last night on the exact same motor and now he is faced with the same decisions.

Well thanks everyone for some input. I did the de-carbonizing thing a few weeks ago while on my boat lift. Didn't clear anything up. I hold onto a tiny bit of hope with Boilerguy's head gasket theory, but I have a feeling that the cylinder is scored. This morning I looked at the head and there are maybe 15 or so bolts for both top and bottom cylinders. Assuming that I take these off and then see the cylinders. Then just reverse the process using the same gasket (would likely be replaced anyway with a rebuild)? Anyone know the order and torque for bolting back up? Would be good information for whatever I decide to do with the boat (rebuild, part out, or sell as is with disclosure).

I don't know the torque specs and tightening order off hand. A manual or some one else may be able to chime in.

I doubt using the same head gasket is a good idea. They are flexatallic. Once compressed they are pretty much done. You will be hard pressed to get a good seal if you re-use it.

BradT,

If you have any questions you can reach me on my personal email: ssolberg1 (at) juno.com

The 15 bolts are for the water cover. You want to take the larger 1/2 inch head bolts (10). By chance you dont find scoring, 18-20 ft lbs, work your way out from the center incrementally, and use a new gasket.