Hard starting 1979, Johnson 70 hp, 3cyl.

R

RJDAWSON

Seaman
Joined
Sep 4, 2005
Messages
54
While fishing Florida saltwater in March, my 70 hp johnson became slugish at start up.
Flushed out after our last fishing day and returned to Indiana.
I had not started it till 1st of June.
last weekend started to go fishing here and the motor would not crank with the
starter. I had to remove the spark plugs and get out the socket and breaker bar to turn
turn the motor. I sprayed penetrating oil in the cylinders and turned the shaft till it smothed out.
Flushed with carb cleaner and was able to start and run it. Still slugish at start up on the lake, but it pushed us around.
Anyone have an opinion about 2 cyl engine oil brand. I am mixing 50:1 but not sure cylinders are being lubed enough.
How does the crank shaft rollers get lubed?
I look forward to learning more about this from you guys.
 
BonairII

BonairII

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Messages
2,727
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

Spraying carb cleaner is no substitute for opening the carbs up and giving them a good cleaning. My '77 75hp Evinrude(which is almost identical motor as yours) starts quickly and idles low with no probs at all cause my carbs are squeaky clean.

You need to open the carbs and clean all orifices. It's not complicated at all. If your fuel lines are old...replace every last inch of it(including all line on the motor itself). Older fuel hose will degrade internally and continue to foul your carbs.
 
B

boobie

Supreme Mariner
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Nov 5, 2009
Messages
20,826
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

How long did this mtr sit without being run ?? Was it fogged out before that ?? Have you done a compression test on it ??
 
J

James R

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Feb 1, 2007
Messages
2,679
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

Sounds like a typical case of neglect. Compression check to see if the motor is worth spending money on. If good you need to test the sparks. If good then the carbs need removing and stripping. I use Gunk carb and parts cleaner. I also run them thru my ultrasonic tank but soaking and carefully wire probing to clear the tiny drillings will do the job. Rebuild with new kits.
Exposure to salt water and salt air does a number on motors and crank shaft and bearings could be damaged. Dont forget to replace the pump impeller and lower unit oil.
I use a mix of Marvel oil and two stroke oil to free up and break down any corrosion. Seems to work. Use a water trap filter and Stabil in your fuel.
I use Penzoil Synthetic Blend on all my motors with excellent results.
A manual on your motor is a good investment.
 
R

RJDAWSON

Seaman
Joined
Sep 4, 2005
Messages
54
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

The question had nothing to do with carb function.
Thanks.
 
R

RJDAWSON

Seaman
Joined
Sep 4, 2005
Messages
54
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

The motor would not turn. I had to manuelly turn the flywheel to free up the motor. The motor had not been fogged. It had not been started for 3 months. Again "became slugish to CRANK druing a week long fishing trip".
 
D

daselbee

Commander
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Jan 20, 2009
Messages
2,765
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

It is not too good that you had to use a breaker bar to get the engine to turn after sitting.

Those engines are prone to having water leak into the cylinders from the exhaust side...the webbings/castings behind that plate on the stbd side get corrosion...gasket leaks...etc, and you can get water in the cyls.

So, you let it sit, and it locked up....and you had to break it loose with a breaker bar....

Not good.

The fuel/oil/air mix goes thru the carbs...gets atomized there....and passes thru the reeds. Just on the other side of the reeds is the crankcase/crankshaft area. Basically, all that atomized fuel and oil "mists" or saturates over the crankpin/rod and oils the roller bearings.
It gets quite oily in there.
There is no oil pump as in a car. There is no pressurized oil system that lubes the bearings.

I hope the damage is only to the cylinder wall that took on the water and caused the powerhead to lock up. If there has been water on the crankpins/bearings the crank has surely started to rust by now. That is the end of that crank, as they cannot be turned down.
I don't think you will be able to polish out any rusting.....

If it were mine, I would first do a compression test, then pull the cylinder head now, and inspect the cylinder walls.
You can also look at the plugs. Any water in the cyls will wash the plug clean.

Good luck.
 
J

James R

Commander
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Feb 1, 2007
Messages
2,679
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

RJD We cannot force you to use the information we provide. Be assured that we do have a little experience in these matters.
If the motor is still a problem to turn over by hand after soaking in the oil mix then start stripping it down as daselbee suggests.
 
D

daselbee

Commander
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Jan 20, 2009
Messages
2,765
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

Yes...here you go...Durban has been all through this same engine, and I THINK, can verify my claim that these bad boys leak water from the exhaust side into the cylinders.....he even has pictures.....

Read his stuff......

Durban,......the thinker......:)..he questions everything....
 
R

RJDAWSON

Seaman
Joined
Sep 4, 2005
Messages
54
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

BonairII said:
Spraying carb cleaner is no substitute for opening the carbs up and giving them a good cleaning. My '77 75hp Evinrude(which is almost identical motor as yours) starts quickly and idles low with no probs at all cause my carbs are squeaky clean.

You need to open the carbs and clean all orifices. It's not complicated at all. If your fuel lines are old...replace every last inch of it(including all line on the motor itself). Older fuel hose will degrade internally and continue to foul your carbs.
Click to expand...

It was clear that the 1st responder had not read the post or the question.
The advice I have received over the years from this site has been invaluable towards working on this motor.
I have found the problem.... my old batteries had lost thier cranking amps. Terminals cleaned and away we go.
Compression 120psi on all cylinders.
I had just been told that Quick Silver 2cyl oil was the best choise.
I will also take more time flushing in the future.
 
R

RJDAWSON

Seaman
Joined
Sep 4, 2005
Messages
54
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

As far as the rest , lower unit oil changed last fall and new water pump installed.
Still the old girl needs some work but when she gets it she gets it.
 
D

daselbee

Commander
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Jan 20, 2009
Messages
2,765
Re: Hard starting 1979, Johnson 70 hp, 3cyl.

Did I misunderstand?

If I read this right, you had to use a breaker bar to get it to turn, and now you still have 120 psi on all three?

Remarkable.
 
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