Another new guy question

[tinkerman]

Ok while I’m waitin for my impeller for my QD-16 I started another project. I’ve got two mid 60’s Johnson 3hp twins. One of them the prop doesn’t turn when you crank it. The other has an old piece of masking tape on it from 2011 that says runs then stalls. Compression on both these engines is 50# both motors both cylinders. That’s with a battery drill on the flywheel. Common sense says that’s too low. Are there parts still available for these engines? Is it worth it to tear down and re ring if cylinder and piston look ok? I’ve actually heard these were great motors and I’d like to put this one on my kayak.

It's a jungle out there.

[frankr]

Lots of parts are still available and those that are NLA can usually be found from our members. The one that won’t turn likely has stripped splines, so that would be a parts motor. 50psi is too low, if that is a correct reading. Possible blown head gasket between the cylinders

[tinkerman]

I pulled the head on the one that the prop turns and cylinder looks good. Piston still is snug in the cylinder, just a “touch of wiggle” if you really try. (I’ve seen old Kohler engines have 3/16 of slop and still run, but I’m not familiar with 2 strokes.may round up some gasket material and go from there. Wish I would have mixed some dish detergent up and soaped around the gasket first

It's a jungle out there.

[crosbyman]

http://www.outboard-boat-motor-repair.com/Evinrude%203%20HP%20Lightwin%20Outboard%20Boat%20Motor/Evinrude%20Johnson%203%20HP%201952-1967%20Ignition%20System%20Tune-up.htm

http://www.maxrules.com/fixtuneitup.html

Joining AOMCI has priviledges 🙂

[fleetwin]

I am assuming you checked the shear pin on the 3hp with the prop that doesn’t spin with the flywheel….If that is OK, then I will sadly agree with Frank, the crank/driveshaft splines are probably shot, which is the end of the road for this engine.
And yes, 50PSI is pretty low, but not shocking for this little engine. You have the head off now, is the head gasket OK? These engines have such small combustion chambers, compression gage readings are often inaccurate. Compression readings are usually between 70-90PSI for these little engines. If it was mine, I would not tear it apart. I would use some fine emery on the cylinder walls and give it the 50cent hone job. Resurface the cylinder head to make sure it is flat, then reassemble with a new head gasket. I’m betting it will run and the compression will come up a bit…I am assuming there is not aluminum scuffing on the cylinder walls or major scoring.
You could always pull off the exhaust cover (if it is a fresh water motor and the screws aren’t rusted/stuck), this will give you a better look inside to check the pistons for stuck/rusted rings, or scuffs and scoring on the pistons….

[tinkerman]

The cylinder and piston (what I can see of it) look good and pretty snug fit of piston to cylinder. I think I’ll take the advice of getting a cpl gaskets sand the cylinder wall slightly and see what happens. One engine is getting good spark on one cylinder and nothing on the other and the other engine is getting no spark either cylinder. Hopefully I can get both cylinders on one to spark. Then I’ll scuff cylinder, clean carb and tank and just see what happens. I’ve only been interested in these old motors a few weeks. (I now have 9 lol) But I guess you learn as you go. Next time I buy one I’ll for sure take a compression gauge with me. No compression seems to be a deal breaker right off the bat due to parts being NLA. (Disappointing) carb kits impellers gaskets and ignition seem to be a little easier to find, and you have the option of used for these also. I bought about 6 of these motors from the same individual, who was a lot less than honest about at least 3 of the engines. From the looks of his shop and talking to him he has been collecting and fixing these old motors for a while. He knew I was new to the hobby and let me leave there KNOWING the two Johnsons were low compression and also got a 39 Neptune that’s got ignition problems (when I asked about the ignition his reply was I’m not sure I havnt checked it, but he seemed to be able to tell me every engine he had that would run lol) also parts missing from lower unit in Neptune. There’s good and bad in any hobby I reckon, but like I said there’s a lot that you learn as you go. Seem to be some helpful people involved in the hobby also, hope to meet a few of them also

It's a jungle out there.

[outbdnut2]

If your compression gauge has a rubber hose and the check valve is at the gauge instead of at the end that attaches to the motor, you will get low readings like that on these small engines due to the volume of space in the hose. These motors are sometimes known to blow the head gasket, creating a path in between the two cylinders. If this has happened, you will get low compression readings and the compression will be the same on each cylinder. Removing the head, you can easily see the bad spot in the gasket. If the head gasket is bad, as described, you will probably not be able to get it to run.
Dave

• This reply was modified 6 years, 1 month ago by outbdnut2.

[tinkerman]

Thanks Dave , both of those points make good sense. However I just checked and the check valve is at the threaded end. I stuck the head back on but I think I’m gonna order a head and Intake gasket see if I can get both cylinders firing and see what happens. I don’t mind spending a few dollars on it (it’s knowledge gained , right?)

It's a jungle out there.

[fisherman6]

Tinkerman,

Any of us that have not worked on outboards for a very long time end up paying for our education early on in our involvement in the hobby, especially if we do not have someone as a mentor to keep us on track. Believe me, I certainly did when I got started. It does seem that the individual that sold you these motors could have been more forthcoming with information on what he sold you. I do not want to sound like I am defending him here either. I will say this, however, You said from talking to him and looking at his shop he has obviously been doing this for quite some time. Much of the other things that you say this individual said to you when asked about these motors sound very much like what someone who has been doing this for a long time would say. Ignition problems are typical and are something that usually needs to be addressed on many old outboards. Low compression is not unusual either, but very low or no compression means you’re buying parts. Not necessarily a deal breaker but definitely puts it into a lower price category.

When he said that every engine he had would run I would not consider this dishonest. Perhaps not forthcoming to a person new to the hobby and wanting to learn, but not dishonest. I have been doing this for a while now, but certainly not so long that I have forgotten what it was like being new in the hobby. I think the difference here is the understanding between “will it run” and “does it run”. I have LOTS of motors in my collection that “will” run but currently do not. Do I know what it will take for each of them to run? No, I do not. When I was just getting into this hobby I likely would not have considered this terminology to make a big difference. Several years and MANY motors later I can say it makes all the difference. This serves as a reminder to me and possibly others that have been doing this long enough to pretty well know what we are getting into when we buy a project motor. I need to be careful how I use my terminology around someone fresh into the hobby, especially if I am selling them something or giving advice on something they may wish to buy from someone else. I have probably around 70 motors that ‘do’ run and probably another 90 that ‘will’ run if I so “will” them to. I also have another batch or partial carcasses that have and do donate to the cause of getting those “will” runners back to “do” runners. Even the carcasses “will” run with enough parts and time. At this point for me in this hobby I would consider a motor that “will” run one that is 90%-100% complete, has fair to good and even compression. This would be a ‘will run’ motor for the purpose of sale as such to another person in the hobby. This motor may or may not run as-is. I’m just wondering if this may be a case of the seller unintentionally misleading you into thinking the 3 more questionable motors were something they are not? I can see where this could happen. Just trying to offer a perspective and not come off sounding like a jerk.

-Ben

OldJohnnyRude on YouTube

[tinkerman]

Point well taken. I understand what your saying. It’s always good to get another perspective. I am VERY new to this hobby and enjoy it, just enjoy fixing something old and seeing it used for it’s original purpose again. Being very new and realizing the internal parts are the hardest to come by, my first test from here on out will be compression. If I learned this in a matter of a month or so, I would think this guy knew the same thing and had checked the compression on the johnsons and could have said compression is pretty low and may be better parts motors than runners being how parts are scarce. But maybe he didn’t check. It’s all good. As I said we learn as we go for sure

It's a jungle out there.

[Author]

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