88 Johnson Sailmaster 6.0, I killed it... no spark

[trimoon]

I bought this engine about a month ago second hand and it would run great,warm up until i put load on it, then it would eventually stall out and not start again until waiting a while. Its a manual pull and has no battery. The impeller seemed to be working fine for cooling and the engine never felt hot when i took off the cover, so i dont THINK it was overheating.
After waiting a while it would turn over again.

After the last time I killed it I couldn't start it again at all.
Cleaned the spark plugs, span the flywheel by hand (is that enough or should i be pulling the starting cord and having a second person hold the spark plug?) while putting the spark plug very close to the ground and no spark.
I took off the flywheel and cleaned the rust off the flywheel where the magneto contacts it. Didn't seem too bad. Is there a way of testing these? I didn't see any cracks or significant signs of wear (all magnets still painted perfectly green.)
I tested the coils and both of them are showing the same resistance on the secondary terminal to ground.
I took off the rectifier and tested red and 3 yellow / stripe leads. All showed resistance one way, and not at all when i switched the leads.
Ive got the power pack dissembled now CD2 583169 19 E M-OA and have 131 and 133 k ohm resistance from coil inputs to ground wire. Is there any test for the power pack?
I tried to go to the library but they didn't seem to have too many books on smaller Johnston kicker engines that were in the 88 range.
Also it usually makes a flywheel turning noise and a clucking noise trying to turn over, its just the flywheel noise now...

Could I hook up a multimeter to the input of the coil or would the V still be too much even before the coil and kill the meter?

I don't want to just start replacing random parts without ruling things out a bit more. Any help in the right directing would be really appreciated!

[jonesg]

Test the coil , sometimes they burn out, internal winding breaks, the spark will jump the broken wire for a while but then you lose all spark for good.
If theres any cracks on the coil its junk.

Put an ohm meter from the primary ( usually small black wire) to the green wire (ground) , it should peg the meter.

Now put the meter from the sparkplug wire to ground, should be 6 ohm+-.
If you get no reading the coil is shot.

[trimoon]

There's 2 coils. Here's a picture of one:



The power pack goes to the small lead on each and the big lead goes to the spark plug. The small lead to ground shows almost no resistance (<1 ohm) and the big lead to ground is 250 ohms on one coil and 258 ohms on the other. <1 ohm reading from the small lead doesn't sound right, but then again the engine was running on both coils and then just suddenly stopped. That makes me think its not the coils.

[trimoon]

Oh i just realised you probably mean the magneto coils. Ill take off the fly wheel and check these after work. Thanks!

[jonesg]

no those are the coils I meant, but you have power packs, I was thinking a points system, so they are probably good.

go to an auto store and get a cheap spark GAP tester and check for spark, set it around 3/8th inch gap and give a healthy pull on the start chord.
Its easier with spark plugs out, ground the other spark lead to the block.

If you get spark then its the carbs in most likelyhood.

[trimoon]

I have one of those spark testers that you wrap around the lead and it lights up an led on the end... not lighting up when pulling the cord.


Ill go buy a spark gap tester though, they look like a better tool.

[jonesg]

yeh you need the adjustable gap tester, they're cheap and very usefull, nothing like a bright blue crack to indicate spark.

is it elec start?
I'm wondering if its elec start and you don't hook up a battery what might become damaged, rectifier , regulator?

[trimoon]

Ill keep looking for an adjustable gap tester. 2 auto part places I went to didnt have it. No its a manual start, no battery. Im starting to think its the power pack but i dont want to just throw $100 at it and have that not be it.

Thanks!

[jonesg]

Try napa , autozone or sears.



You can put a meter on the output wires from the PP to the coils and see if it puts a pulse out when pulled through.
Don't know what the reading is supposed to be but if the readings are close for both coils its safe to say they are probably correct.

If the coils get no input voltage they can't spark.
What does it use for a timing sensor? Points?

Check kill switch too.

[trimoon]

Put a volt meter to the coil input leads and got anywhere between .5 - 4.8v max on one and the other maxed out at 5.2v

I can now see a spark going across the spark gap end so I guess that means the ignition is good.

I did a compression test and got 28 on first pull to 40/45 by 4th pull. Is that typical compression for a small engine? The spark plugs do have a little bit of gas on them.

As far as the timing goes i didn't see any points under the flywheel or anywhere so im thinking it uses a plate type timing.

I guess the next step ill take is pulling apart the carbs and seeing if a pin snapped or something...

[trimoon]

Oh and kill switch is working.

[trimoon]

Ok well now ive rebuilt the carbs and the engine makes better sounding turn over noise again. It made one loud bang then nothing again after pulling many times. I took out the spark plugs and aired it out, waited 10 mins, pulled it again and another loud bang. I have the carb needle out 2 1/2 turns (starting spec).
I think I know what happened. I took out the thermostat and it looks seized with salt. I think I cooked the engine.

Time to take it apart and do an entire rebuild?

[trimoon]

ok... well I rebuilt this motor and same thing. One loud bang and nothing. Can anyone tell me if a compression test on this motor resulting in 40/45 by 4th pull is typical?

I have heard everything from its very low and should be higher to this is more than enough since its a small pull start engine and these show lower readings...

If i find out if this is low or not it would really help me get in the right direction. Ive tried everything on this motor...

Thanks!

[Thumpbass]

I have an '84 8hp johnson and the compression is 120psi on each cylinder...i know it's not the same year or model (as yours) but close enough in my mind to think that your compression numbers are low...if nothin else debunking the theory that smaller engines produce lower compression readings

[trimoon]

Thanks Thumpbass... Ill take it all apart again and check for a hairline crack closer... Something has to be taking away compression. Is your 84 a manual or elec? I head the manual ones read lower.

[trimoon]

Problem Solved...

I took the engine completely to peices, replaced some seized pision rings, now i get 30 psi on first pull, 70 by fourth pull (compared to 28 first pull, 40+45 fourth pull before the rebuild).

The impeller key was missing and thats what caused it to overheat in the first place. What was interesting to me is that there was still water coming out of the cooling loop even without the impeller key in place, so i thought it was cooling ok, just not nearly enough water pressure.

Thanks for the help!