10 HP Johnson

[RonWels]

I have read and heard a few diff. speks on compression. I have the 10HP johnson QD-21(1960), I saw another post here that had a compression of 63 and he thought that seemed good enough. Other's seem to think it should be in the neighborhood of 90 to 110...providing they are the same on both!! Does it mean that if the compression is anywhere say between 65 and 85 that the motor is on it's last leg??

 

[Mas]

Re: 10 HP Johnson

Compression can vary with the tool used and the technique used. What is more important is the psi numbers are relatively even. Low numbers can be brought up with products such as "sea foam" to loosen stuck rings. Head gaskets can easily be replaced if suspect for low compression.

Last long??? Test your compression first.

What are your numbers?

Mas

 

[kfa4303]

Re: 10 HP Johnson

MAs is exactly right. You can different compression readings depending on how you choose to test it. Motors with electric starters generally give higher numbers b/c the start can spin the motor so well. Motors that have had a chance to warm up a bit also tend to give higher numbers. While 65 may be a little low, it's actually not bad for a little 10 hp. As Mas said, it's more important thing is that they be fairly even (i.e. within 10% of each other). I would lay the motor down so that the s'plugs face up, then remove them and pour a little Sea Foam or Deep Creep in each cylinder and let it sit for a few hours/days. Then replace the plugs and fire her up. She'll smoke like #%$$#%, but that's what you want. I would then run a gallon of normal (24:1) fuel mix through it to which you have also added the rest of the can of sea foam to. Again, you'll get lots of smoking, but that's just old carbon being burnt off. I have a '61 QD-22 that I brought back to life, so holler if you get stuck. Here are some great links.

http://www.sschapterpsa.com/ramblings/johnson_QD.htm

 

[RonWels]

Re: 10 HP Johnson

That's awesome..thanks Mas and Kfa. Did the top plug and compression was 73-75 (cold motor). I am still struggling to get the compression fitting/hose to thread on the bottom plug. Space is tight between the plug opening and the casing. I may need an elbow fitting for it to work. NO electric start on this motor. New bottom(prop) seals/rings coming in tuesday from my Johnson dealership. I can also pick up some sea foam then and do it all at the same time....Also, keep in mind that this motor was sitting for 2 years before I bought it.
I did have it running pretty good the other day..just in a drum of water. Can wait to put it on the boat and test it out properly....PS, so your normall mix is 24:1...cause I've heard 40:1 and 50:1

 

[pikefisherman]

Re: 10 HP Johnson

I would check before running this motor 24:1 Mine is the same year I run 50:1.The sea foam where did you buy it?

 

[Mas]

Re: 10 HP Johnson

I would check before running this motor 24:1 Mine is the same year I run 50:1.The sea foam where did you buy it?

Get it from any auto store.

mas

 

[Mas]

Re: 10 HP Johnson

I would check before running this motor 24:1 Mine is the same year I run 50:1.The sea foam where did you buy it?

If the con-rods have only bushings and not needle bearings, I would use at least 24:1

Mas

 

[kfa4303]

Re: 10 HP Johnson

24:1 is the correct mix. they didn't go to 50:1 until around 64-65. you may even want to run a gallon of 16:1 through it for starters just to get the innards well coated with fresh oil after sitting for so long. always better to have a bit more oil than not enough. 24:1 is roughly 5.5 oz per gallon, but I just round up to 6 oz. per gallon. It may smoke a bit in the test tank and the water will get pretty oily, but once you're on the open water it won't smoke much at all. I get very little smoke out of my '61 running 24:1 on the open water, especially after you decarb it and get the funk out. You can get sea foam at any auto parts store for about $10 a can. It's white and has sort of an old fashioned logo and lots of writing on it. Just ask for it and they'll show you where it is. It's great for your car, truck, lawn mower, or practically any other internal combustion engine. Best $10 you can spend on a motor IMHO. You can get it in liquid or spray form, either one is fine. The spray version is kind of nice because you can spray the sea foam directly into the carb throat as the motor is running as another way to decarb it. Do a youtube search, and you'll find all kinds of vids of folks sea foaming their cars, trucks, boats, etc....They might be worth watching just so you know how much smoke to expect. Good luck. Keep us posted.

 

[RonWels]

Re: 10 HP Johnson

Great sites that someone else posted. Very helpfull.

http://www.marineengine.com/parts/v...ntage-evinrude-johnson/378459/37845900001.htm

http://www.sschapterpsa.com/ramblings/johnson_QD.htm

http://www.outboard-boat-motor-repa...hnson 5.5 HP 1954-1964 Carburetor Tune-UP.htm

I am used to a bit of smoke..when I bought the motor last week I brought it down to the basement, did the compression, cleaned the plugs..etc. After it sitting 2 years I gave her a couple pulls and she started...filled the basement with a nice blue smoke which ended up on the main floor of the house...thank god my wife wasn't home...hehe!
Now I test it out on the back deck.
Next week I will put on the new seals and clean with sea foam....smoke out the neighbors. For now, off camping for our canadian thanksgiving. See you next week and thank's again for the info.

 

[F_R]

Re: 10 HP Johnson

That motor is notorioius for beating the wrist pins loose in the pistons. Running on 50:1 certainly isn't going to help the situation.