compression on a 1958 johnson seahorse 5.5

[Headlight48]

OK.. new here, hope someone responds. My wife gave me a 14 foot aluminum fishingboat for my birthday. Just the boat. A friend of mine gave me an old motor (5.5 hp) that has been lying around for many years. Looks like crap. upon removing the cowling I noticed the power head underneath looks really clean. I did a compression check (never done this before) got around 40 to 50 lbs of pressure in each cylinder. Put some oil (Marvelous mystery oil) in the cylinders and pressure went up to about 50 lbs. Put more oil in the cylinders and let it set over night. Next day check the compression and it read 69 lbs. each cylinder was close enough to the same that I could not tell if there was any real difference. Tried the test about 10 times with variations of course and about 5 of the times the compression was exactly the same in each cylinder. I read some where that a rope pull engine will show lower compression. Should I assume the the pistons and rings are good and just go for a major tune up or should I consider replacing the rings? Any info will be appreciated and helpful. I have never worked on an outboard motor of any kind or a two stroke. I get it that I need a factory sertvice manual and am shopping for one. Mean time I would like some expert opinions or at least some experienced opinions about what I should be considering. with this motor. I really like the prospect of running the outboard.
Thanks Headlight48

 

[1946Zephyr]

Re: compression on a 1958 johnson seahorse 5.5

The fact that your readings are the same, is great. There is no need to rebuild this little gem. I would however replace the impeller and check the ignition system over real good. If the coils are cracked, then they'll need replacing. The points will need to be cleaned and most likely, the condensors will need replacing. The carb may likely need rebuilding too, but I think once you make sure the ignition system looks good, it may likely fire right up.

As far as repair manuals go, that all depends on your mechanical skill. Most guys here will suggest a factory service manual, but I myself, wouldn't see a need to go to that expense and just by a Seloc, at the local marine dealer.

Welcome to iBoats

 

[olenavygoat]

Re: compression on a 1958 johnson seahorse 5.5

I'd have to agree. The SELOC book I have says at rebuild you would be at 90-100 and no difference of 5psi between cylinders. With the age of your Sea Horse I'd let it ride too.

I have a 1951 5 hp and a 1957 10 hp Sea Horses and they're right about where yours are, just broken in!

 

[Headlight48]

Re: compression on a 1958 johnson seahorse 5.5

Great! I was hoping to hear just what you guys arre saying. I think no matter what I'm replaceing the coils, condensers, point and plugs. Thank you for such quick responces.

 

[Headlight48]

Re: compression on a 1958 johnson seahorse 5.5

OK.. Next question. I see that this motor has a reverse. The turn handle, for speed and shifting, barely turns in either direction. Does this series of operations just need cleaning and lubing or is there perhaps a serious problem causing this?

 

[robert graham]

Re: compression on a 1958 johnson seahorse 5.5

Maybe spray all the moving parts and controls with something like Liquid Wrench or similar, to try and loosen them up so you don't break something trying to move it. Good Luck!

 

[JSGOLD]

Re: compression on a 1958 johnson seahorse 5.5

The tiller throttle may just be hung up a bit. My 61' 5.5 is stiff to turn due to age and wear but the plug wires or something else could be catching a bit. The shifter is not supposed to be shifted without engine running but it SHOULD shift from reverse to neutral and forward OK just to test. If this is frozen you might take off the drain plug on the lower unit and see if it might be full of rust /water etc. Actually, you should do that ANYWAY to see what is in there as far as fluid goes....

 

[58rude]

Re: compression on a 1958 johnson seahorse 5.5

The armature plate prob. needs lubed at base and you should be able to pull the plastic grip off the tiller and lube it up a little also. Good luck

 

[Steve A W]

Re: compression on a 1958 johnson seahorse 5.5

Here are some links about "Awakening a sleeping motor"
I learned alot about motors from these sites.
About your compression readings, My 55' 5.5hp. CD12 only had
60psi when I first tested it. It sat for at least 20 years.
Last time i tested it it had 85 psi. Thats after 4 gallons of gas
running it.

http://forums.iboats.com/showthread.php?t=158086

http://www.precisionservoutboard.com/Information/ArtsFivePointPlan/tabid/65/Default.aspx

http://www.duckworksmagazine.com/07/columns/max/articles.htm

On the last one, read the "Start to finish" articles.
Good Luck with Your motor.
Steve A W

 

[jmendoza]

Re: compression on a 1958 johnson seahorse 5.5

My 1954 CD-11 5.5(see below) had about 60 pounds after having sat for decades. The ignitions coils, points, and water pump were renewed, carb rebuilt (take out the welch plug over low speed needle orfices), and I added a Mikuni fuel pump and converted to single line fitting for a modern tank. Magneto plate was stiff, needed lube.

To optimize the engine, timing was set precisely using a strobe type timing light, and the carb linkage was synched to the mag plate. I used Valv-Tect Marine Motor De-Carb in the cylinders once the engine was hot by putting it on full tilt, removing the spark plugs, and putting each piston at TDC and spraying the de-carb solution directly into the cylinder via the plug hole. Let sit 15 minutes and repeat for second cylinder. Ran engine for 1 hour after treatment on lake, and noticed a nice improvement.

Beware, this bushing engine does require 25:1 gas to oil mix. I am using a premium ester based synthetic called Motul, and although it's far superior to petroleum based oils, I do not try and get away with less, but the Motul does leave less carbon and is cheap insurance.

 

[jay_merrill]

Re: compression on a 1958 johnson seahorse 5.5

I look for about 50 - 70 psi on the small displacement, pull start motors. As others have said, the even match is something that you want to see also. Since you have 69 psi and that even match, I'd say that you need to leave the powerhead alone.

You will have to pull it from the midsection, however, in order to change the water pump impeller. While your doing that, you may as well pull the shift lever out of the midsection, so that you can clean it, knock off any corrosion that might exist on the shaft, regrease it and reinstall it. I would also use a long wire brush to clean up any corrosion that might exist on the walls of the molded hole in the midsection, where the handle fits through it.

I agree with the others in regard to pulling the flywheel, in order to check this ignition coils. Cracked coils are very common on very old outboards that have been sitting around for awhile. My personal choice would be to replace the coils, the points, condensors and spark plug wires. Don't forget the take the small metal band off of the top wire on the original pair. You can reinstall that on the new top wire, so that you know which is which.

I think that most of the other items were covered by others, but I didn't see comments about the gearcase. I would replaced the gear oil, as well. As you drain it, look for signs of water intrusion. Be sure to get new crush washers to go under the vent and drain plugs. Many people forget to do this and end up with water seepage into the gear case. After you have properly reinstalled the plugs, run the motor in water for a short while and redrain the gear oil. looking again for signs of water intrusion. Be sure that the motor is run in gear, when doing this.



???

 

[Headlight48]

Re: compression on a 1958 johnson seahorse 5.5

WOW!!! Thanks everyone for the input. Sorry it took me so long to get back but my puter crashed. The more I get inot this engine the more I'm liking what I'm finding. I will do all of the things you guys suggested, at least. And thanks again.. I'm all smiles now. *S*