Questions on a 1963 5.5HP Johnson

zpbruno

Cadet
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Jul 7, 2020
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9
I picked up a CD-20C 1963 Johnson 5.5 HP outboard. It is not seized and the inside looks pretty clean, with newish fuel lines and plug wires which feels pretty good to me for $50. Now on to the problems: It does not give any indication that it wants to start. Previous owner claims it ran for a few minutes last time he had it at a lake, before dying. Here are some observations and questions:

1) Gasket around thermostat cover was blown open. Fixed temporarily with some gasket material cut to shape.
2) Fuel in the transparent glass bowl was yellow, rather than the bluish my fuel turns when I add oil. Is the blue a universal color additive and was straight gas put in there?
3) I get some spark on the #2 lower cylinder, but none on the upper. Looking through the inspection port on the flywheel shows seriously cracked ignition coils, which should get replaced. But as long as I'm getting spark on #2 I should get a t least a cough, shouldn't I?
4) Compression test using my cheap tool yields 30 psi on both cylinders. I read somewhere that these twin low readings imply a head gasket leak so I am taking the head off for inspection.
4a) How much force should it take to remove the cylinder head once all bolts have been removed? I'm 99% certain this motor has always been in fresh water. After removing 10 bolts and trying some light hammering and prying it won't come off. How much force should I expect this to take? Am I missing a fastener somewhere?
5) Impeller is obviously pretty high on my list to check and change. For this motor this requires powerhead removal, so I am waiting on doing that until I at least get a cough out of the motor.
6) There is definitely fuel in the carburetor bowl.
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
38,553
Fact----The magneto on this motor is capable of producing up to 28,000 volts.----That voltage will jump a gap of 5/16" with a SNAP you can hear.-------Spark on one of your plugs in air does not mean it will jump that gap in the cylinder with 80 PSI compression.-----Replace coils , condensers and if points are badly pitted replace them too !!-----Head should pop off easily.---The head will be warped ( they all are ) and you can true it up on glass with some valve grinding compound.----Replacement SIERRA head gasket is the best deal.----And much better than factory original.
 

F_R

Supreme Mariner
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Jul 7, 2006
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28,226
You are wasting your time until you replace those cracked coils.
 

racerone

Supreme Mariner
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Dec 28, 2013
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38,553
Agreed-----With 30 PSI in the cylinders and NO SPARK , you are wasting your time.
 

F_R

Supreme Mariner
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Jul 7, 2006
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28,226
Oops, I missed the part about 30psi. Are you sure about that? That does sound like a head gasket blown between the cylinders. Pull the head and look before spending the coins for new coils.
 

Crosbyman

Vice Admiral
Joined
Nov 5, 2006
Messages
5,695
try a not so cheap pressure meter .... see if things improve but first put those bolts back in :)


take a meter VOM and see if you have continuity between plug boots and engine frame you must see 4-7 Kohms
but first.... REPLACE the coils
 

zpbruno

Cadet
Joined
Jul 7, 2020
Messages
9
Oops, I missed the part about 30psi. Are you sure about that? That does sound like a head gasket blown between the cylinders. Pull the head and look before spending the coins for new coils.

As I said, it is a cheap compression tester and I don't know that I believe the calibration- the number is probably low, but probably not 30.0 psi. I do believe they are identical however, so I went ahead and took the head off. I see no strong evidence of head gasket failure, but boy is there a lot of carbon in there. I did a surface clean on the mating surfaces and the gasket, poured some oil in each cylinder and sloshed it around a bit, oiled the gasket, and closed the head up. Now I'm getting about 35 psi on each cylinder. New Sierra gasket on order so I will do a proper job of it when that arrives.

With oiled cylinders I didn't see any harm in trying out a little starter fluid and I finally got my cough; it ran for 5 seconds. Although I have fuel to the carburetor bowl it looks like it might not be getting to the cylinders. A carb kit is on order now too.

I also now have coils and ignition tune-up kit on order.

Looking forward to the possibility that this thing might run.
 

Crosbyman

Vice Admiral
Joined
Nov 5, 2006
Messages
5,695
try a decarb product like Merc Power Tune (follow instructions)

try another meter
 
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