1969 Johnson 100 hp. Won't Start.

[Jbones1969]

First time post here, so I'll apologize in advance if I'm being repetative.

Bought the boat at the end of last season, only being able to get out twice with it. The first, which was a weekend on the lake, went great, not a problem at all, but the second time out she was run for about 5 mins without proper oil mix and shut down. Afterwards, she wouldn't want to turn over in the driveway with proper mix, and we were noticing that the gear to engage the flywheel was getting stuck in the "up" position, not retracting. Took that apart and greased it up and the flywheel began spinning freely with ignition. After fiddling with the choke butterflies, we were able to get it to turn over.

We thought the problems were solved, but after taking her out again this year, she started up nicely in the water (which leads me to believe there was no serious damage from prior oil mishap the year before), but after about 15 mins, the engine overheated and when we shut down to look at it, would not turn over again, leaving us stranded (thank goodness for trolling motors).

Any ideas as to why it won't start up again? My thoughts are aimed towards the impellor for not cooling down, and perhaps the fuel pump for not starting? Like I said, Newbie alert on this one guys.

 

[jtexas]

Re: 1969 Johnson 100 hp. Won't Start.

When you say "run without oil and shut down" you mean you realized your mistake and shut her down, or she shut herself down?

By "not turn over" I assume you mean the starter is spinning the flywheel at a pretty good speed, but the engine won't start?

The overtemp horn alerted you to the overheating? good job shutting her down right away.

Back to basics - compression, spark, fuel:
1st do a compression test - any damage will likely show up as poor compression on one or more cylinders.
2nd do a spark test - look for strong blue spark across a 1/2" gap (spark tester, couple bucks at auto parts store).
3rd if you got good spark, then put some 50:1 premixed gas/oil in a spray bottle & spray into carbs while cranking - see if she'll try to start.

If you don't know the age of the impeller or if its more than 2 years, go ahead & replace it now. If the housing is scored or scratched inside, replace it as well. Does that motor have a telltale?

Report the results of your testing.

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

Well, it wasn't exactly no oil, it was just the wrong mixture, but alot less than it should have been. And yes, we shut it down, but now, even with the proper mix, she doesn't want to start up again. Heres what I do know:
- Brought it into a local shop. Mech told us over the phone that the compression levels are under 100, and we should just scrap the engine. My thoughts are he either doesn't want to work on an older motor, or hes looking to scam us into buying new which, surprise surprise, he can offer a good deal on almost new!
- He wouldn't give us a compression figure, just that it was "under 100", which could mean anything, especially given that the motor is cold (not started) at the time.
- I know the carbs and rings haven't been cleaned in a while, which I'm assuming is also contributing to low compression.
- Also, when working on her at home, the only time she wants to start is when spritzing the carbs with premixed gas, which leads me to believe there is a problem with the fuel pump.

As for the plugs, I'll have to check those hopefully tonight. What should I be looking for in the ways of a "Tell-Tale".

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

After browsing other posts, I'm starting to be hopeful that cleaning/rebuilding the carbs, may be the key to why she's just not starting, and that the low oil ratio was the reason for overheating.
If this is the case, should I still be worried about compression levels under 100?

 

[hoeser]

Re: 1969 Johnson 100 hp. Won't Start.

Under 100 is pretty vague... 70psi? Yeah, It'll probably run like garbage... 95psi will probably run just fine. I was running last year (pre-rebuild) pretty well on 80-85psi across all 4 on a 140 crossflow... Buy yourself a cheap compression tester, check it yourself. Even if its really bad (like 70psi) it should still run, probably just wont idle very well.

I'm still not sure what you mean by "wont turn over" - to me that means the engine is seized, I think you mean "turns over but wont fire".

Don't scrap it just yet.

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

Haha, I suppose, my mech lingo isn't the greatest.

 

[jtexas]

Re: 1969 Johnson 100 hp. Won't Start.

Difference between cylinders is more important than the actual compression numbers. I agree with hoeser...under 100 is showing its age, but if the lowest is within 5% of the highest, then it's not ready for the scrap heap yet. If you paid the guy then he owes you the compression numbers; if he didn't write 'em down or can't find 'em, then forget him.

A compression gauge would be a pretty good investment at $30 or $40. And a manual.

Sounds like you're on the right track with the carbs. Might want to think about thermostats.

And if you haven't yet, look for the "decarb" thread in the engine FAQ section.

Just saw your question about a tell-tale, also known as "pee stream", AKA "overboard water indicator" - it would be a small hole at the bottom of the cowling, starboard side, where a stream of water exits to let you know that the water pump is pumping. Some years, they left 'em off.

What's the model number of your engine....are you sure they made a 100hp in 1969?

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

Finally got the numbers from the mechanic. Turns out the compression is at 90 on three and about 85 on one. Today I found out from talking to colleages that the place I took it too, has repeatedly turned down service to older motors. Guess they only like working on new gear.

Tex, what did you mean by, I might want to check the thermostat as well? Also, if I hadn't want to take the whole thing apart to get to the carbs, is it fine to spray a carb cleaning solution and let it sit for a bit? Thoughts?

 

[hoeser]

Re: 1969 Johnson 100 hp. Won't Start.

That engine will absolutely run with those compression levels if everything else works (fuel, spark, etc).

There isn't much to take apart to get to the carbs where jtexas wants you to spray... I believe on that engine its just a breather box cover you need to remove.

Your thermostats might be stuck shut thus not allowing cooling water to get into the engine, hence why it overheated. Most people blame the impeller for this... which isn't always the case. Though it could be the impeller, or both.

I suspect that the overheat damaged some electronics resulting in no spark conditions hence why it wont start now even when cold. Check your spark.

If you get it all working, decarb that baby and I bet you'll see numbers close to or over 100.

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

How would I be able to check the thermostat to make sure it's functioning properly or not?

 

[hoeser]

Re: 1969 Johnson 100 hp. Won't Start.

I would think that to be difficult without a running engine... but someone may be able to offer some insight. I would inspect the impeller first before attempting to run the engine.

 

[dooma_Flatchy]

Re: 1969 Johnson 100 hp. Won't Start.

Finally got the numbers from the mechanic. Turns out the compression is at 90 on three and about 85 on one. Today I found out from talking to colleages that the place I took it too, has repeatedly turned down service to older motors. Guess they only like working on new gear.

Tex, what did you mean by, I might want to check the thermostat as well? Also, if I hadn't want to take the whole thing apart to get to the carbs, is it fine to spray a carb cleaning solution and let it sit for a bit? Thoughts?

You don't want to use carburetor cleaner.. It has no oil and I will remove the remaining oil you have left and possibly do internal damage.

 

[jtexas]

Re: 1969 Johnson 100 hp. Won't Start.

Your thermostat is at the bottom of the powerhead, at the back - basically you'd put it in boiling water with a kitchen thermometer & watch for it to open at the proper temp (somewhere around 125 to 140? I think?).

You can't really clean a carburetor without taking it off the engine - but you don't know yet whether you have a spark problem or a fuel problem.

You can check for spark by removing a plug, reattach it to the boot, and ask your mother-in-law to hold it against the engine block while you engage the starter. If she screams, you got spark. seriously, use a spark blug boot tool or insulated pliers or something. Do that on all 4. That'll confirm whether you got spark or not, but won't test the quality of the spark.

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

Last night we removed the bottom end, and took a look at the impeller. Looks great! There was a lot of gunk that we removed, and did some other cleaning up. Tried to start her, but she didn't want to. After 2 sprays of pre-mix into the carbs, she started in about 3 cranks. Ran and idled perfectly. So I'm assuming its not a problem with the spark. We are going to look at the fuel delivery system, I have a friend who is more knowlegeable on the subject, but for my knowledge, what sort of things should I look for?

Also, Dooma, you say not to use a carb cleaner? Does that include something like Sea-Foam? And so, you say NOT to spray them without taking them out of the engine?

 

[hoeser]

Re: 1969 Johnson 100 hp. Won't Start.

How long did it run after you sprayed? Did it start while you were spraying and continue to run after you stopped spraying it? If not, I would point the finger at the fuel pump.

Need a little bit more information for diagnosis.

 

[jtexas]

Re: 1969 Johnson 100 hp. Won't Start.

bones, the thing about carb cleaner is not to run the engine on it, that engine gets its lubricating oil from the gas/oil mix. Seafoam is great stuff and can be sprayed into the carbs but it's not a lubricating oil (says so right on the can). It'll clean carbon deposits out of the engine, but its not a carb cleaner. Carb cleaners have stuff like acetone and methyl ethyl ketone, stuff that will burn your lungs if you get too close. Seafoam is light oil, naptha and alcohol.

You can't get the cleaner inside a carb where it needs to be while its bolted to the engine.

That you can make it run by squirting gas down the carb throat does confirm that you have fuel delivery issues. If you can keep it running by pumping the primer bulb, pretty much means the fuel pump is shot.

Inspect all the fuel lines, look for stiff hoses, listen close for air leaks at the fittings while you pump the primer. Look for gas on the outside of the carbs or leaking anywhere around there. The fuel line should hold pressure for hours and the tank vent needs to be open.

Be aware that your motor can sound great in the driveway on the muffs, and still crap out when you put a load on it - we've all been there.

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

Newest info: Once spraying the carbs with premix, she starts up fine, runs great, and when shut down, starts up great right away. My mechanic friend took a look and knows exactly what part needs replacing, but its name escapes me right now. Also, when tinkering in the bottom end, another friend must have loosen some connection because now putting her in the water, she doesn't want to engage the forward gear. Goes backward alright, which is odd.

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

New update, scratch that, won't change gear. Stays in neutral. Rev's fine, but won't engage gears. Any ideas?

 

[jimmbo]

Re: 1969 Johnson 100 hp. Won't Start.

New update, scratch that, won't change gear. Stays in neutral. Rev's fine, but won't engage gears. Any ideas?

Bad switch in control box, forgot to hook up shift wires when reinstalling gearcase?
Well it's is not a 1969 since there wasn't a 100hp in 1969. There was a 100hp in 1966, 67, 68. Then again in 71 and 72, but a totally different engine.

 

[Jbones1969]

Re: 1969 Johnson 100 hp. Won't Start.

Good eye Jimmbo, I've since found out that she's a '68. Last night we took the whole lower end apart, rewired, and tested it to a battery. Works fine, so the problem must be higher up.