1977 Johnson 140 can’t turn over

[Jakensmith12]

I have a 77 Johnson 140 that I recently obtained and spruced up that I’m attempting to crank for the first time. Initially efforts had the starter engaging turning the flywheel maybe a few inches before stalling out and not being able to turn anymore. I replaced the starter as it already appeared not in the best shape so I went ahead and replaced it. Brand new starter on, turns the wheel but very slowly, coming to almost a full stop on each compression stroke.

Plugs removed it turns excellent just as it should.

Have tried 3 batteries, all directly connected to the starter using heavy wiring.
465 cca
565 cca
845 cca

While the performance improves slightly with a larger battery it’s not enough to expect it to do much better at 1000+.

Before I jump back into it too deep on a whim, anyone have any ideas on what the issue is?

Here’s a video of it, this is with a 845 mca brand new battery.

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[racerone]

Bad starter.---Bad lower unit, checked the oil ??--Bad solenoid ?--Bad cables?-----Bad bearings in engine.------Simple test, can you ( or neighbor ) pull it over with a rope on the flywheel?-----Should be easy to figure out.

 

[Jakensmith12]

Lower unit isnt engaged, have tried also turning it over with the lower unit removed with no changes.

Battery is hook directly, bypassing the solenoid.

With the plugs removed, it turns quite freely as it should so I don’t believe it to be a bearing issue.

With the plugs in you can rotate the flywheel with a wrench on the nut, but it feels much harder to turn than it should be, whereas with the plugs out you can easily turn it with one hand.

My current guess is I’ve made a mistake with eh exhaust gasket or powerhead gasket, potentially causing too much back pressure?

 

[saltchuckmatt]

Sounds like your motor had more than a spruce up.

With all the plugs out can you perform a compression test?

 

[Jakensmith12]

Lol by spruce up I meant It was largely taken apart to be painted, inspected but put back together with the original parts with new gaskets. a deep clean but not many parts replaced. Aside from a carb being replaced all the internals are untouched.

I attempted to do a compression test but even the gauge on a single cylinder causes the same resistance as seen in the first video. Turning at that speed it’s producing around 70psi per cylinder. However that was on the 565 ccs battery and I can try it again on the stronger battery early this afternoon.

I’ve attached a second video showing it turning with the stater with no plugs in just for reference of the difference.

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[saltchuckmatt]

Dry motor with no lubrication?

When you had it apart was the exhaust completely clear? Mud dobbers or something?

 

[Jakensmith12]

I don’t believe so. I’ve gotten home now, took off the exhaust cover and inspected it, no clogs.
Opened up and attached a video of the piston from the side.

Seemingly the resistance is purely the compression and suction created at the end of the stroke. Could 845 mca just not be enough juice?

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This video is unavailable.

streamable.com

 

[racerone]

No such thing as too much compression / suction / back pressure in my opinion.-----Can you or a strong teenager pull this motor over with a rope on the flywheel ????----Was the crankshaft out ???----If so was the center bearing lined up on the dowel pin ?

 

[Jakensmith12]

Flywheel seems to be installed correctly, again when the compression is removed from the cylinders everything turns free as a bird.

Can’t say I have a spare teenager around, but I’m sure I could rig something to be able to manually pull it but wouldn’t that be a bad idea if there is something wrong with my reassembly? Crank never came out, everything seems to be fine looking in, no strange sounds/no grinding/plugs out it turns over smooth. Just as soon as the compression is added back starter can’t hang.

I’m just not experienced enough to know if the engine is abnormally hard to turn over due to something I’ve done wrong or if my starter is just inadequately powered or faulty.

Battery the size of the one I have seems like it should be enough, and the stater is new, not OEM but is from db electrical and should be a good part. Using automotive jumper cables directly from battery to starter.

 

[racerone]

Some want to argue.------Here I would take the starter apart to determine the condition.----Easy to do and costs no beer tokens.

 

[tphoyt]

It be worth a look see even though it’s new if it were dropped and cracked a magnet it will not provide full toque. Even with the plugs out in the vid it didn’t seem to be spinning very strong.
Do you have good clean ground contact?

 

[tphoyt]

Thinking of grounds did you paint the block? If so try removing the paint where the starter contacts the block so it a good clean metal to metal contract.

 

[Jakensmith12]

Thinking of grounds did you paint the block? If so try removing the paint where the starter contacts the block so it a good clean metal to metal contract.

Tomorrow I’m going to do just this! Went and got new cables and connectors and gonna really guarantee my connections are good, just seems like the only possible culprit at this point.

 

[saltchuckmatt]

What is your voltage at the starter when jumping it? I believe, if I'm remembering this correctly, it shouldn't be less than 10.2 volts.

 

[Jakensmith12]

Pulled the starter, cleaned all the connection points with a wire brush to nice bare metal.

Used some brand new 10 gauge 12 foot jumper cables.

Improved a slight bit but not much.

Have 12.56 volts at the battery.

 

[Willyclay]

Used some brand new 10 gauge 12 foot jumper cables.

IMHO 10 gauge is too small. Try 4/6 gauge. It's usually the simple stuff. Good luck!

 

[saltchuckmatt]

Volts at the starter while it's spinning.

Load test the battery with an old school toaster tester not the digital junk.

Cleaning the outside of the starter? Look inside.....easy.

 

[Jakensmith12]

After changing out my battery cables with 4 gauge wire, she fires like a champion!

 

[Willyclay]

Attaboy! Thanks for letting us know. Hope that great old motor serves you well.

 

[racerone]

See post #2 on this saga.