Cracked stator

rob 135

Petty Officer 2nd Class
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Aug 8, 2013
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167
1973 135 hp Johnson .. Last year I put new stator in , tearing down today to put some pistons in noticed stator has some cracks in the coils . Not big but enough so a little gunk was coming out forming a drop on bottom of coil. What would cause that with new stator? Don't want to buy another one this year too
 

Joe Reeves

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Feb 24, 2002
Messages
13,262
Re: Cracked stator

Those pictures are of the old style stator which has no insulation against the heat generated by the fylwheel magnets whirling around the stator. The newer stator is a completely sealed unit. The black coils visible here are the two coils that provide approximately 300 AC volts to the powerpack capcitor, needed to energize the powerpack.

When those large black coils start to melt down due to the excessive heat, a voltage drop takes place that results in weak, erratic, and eventually no ignition/spark. Bottom line... replace that stator with the newer style stator #581225.
 
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rob 135

Petty Officer 2nd Class
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Aug 8, 2013
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167
Re: Cracked stator

That one cost a bunch . Can't afford that again .
 

F_R

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Jul 7, 2006
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28,226
Re: Cracked stator

The original ones back in '73 did that in just a year or two. It's surprising that you got one from stock that old. Maybe it is an aftermarket unit?
 

rob 135

Petty Officer 2nd Class
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Aug 8, 2013
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167
Re: Cracked stator

It was a NOS one from eBay. Was the same as original. So I figured was right one. Old one had big cracks and ran for years . I don't think mine is gonna go from those small cracks I hope !
 

boobie

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Nov 5, 2009
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20,826
Re: Cracked stator

Run it until it quits. JMHO. I've seen a lot worse than that and still working.
 

Joe Reeves

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13,262
Re: Cracked stator

I'll be waiting in the wings to say "I told you so". :)
 

rob 135

Petty Officer 2nd Class
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167
Re: Cracked stator

Ohh I believe it will fail , just not in budget yet . 700 bucks for rebuild parts wiped me out.
 

Joe Reeves

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13,262
Re: Cracked stator

So is it just heat that causes it.

On that older style stator, yes, that is the case. However, what usually happens is that the rectifier shorts out for some reason which causes the tachometer and charging system to malfunction. This results in the stator being unable to have its voltage, power current, (however one wants to look at it) flow thru the circuits to charge the battery which in turn results in that power etc backing up at the stator and baking it bad..... Meltdown!

Hopefully your present stator holds up for awhile... I understand the $$$ scenario.

Might be a good idea to check that recifier as follows:


(Small Rectifier Description & Location)
(J. Reeves)

On most 2,3,4,6 cylinder engines, the small rectifier is located on the starboard (right) side of the engine just in front of the engines electrical wiring strip. There are a few older V4 engines that have the wiring strip on the rear portion of the engine and the rectifier would be located just under that terminal strip. The smaller horsepower engines usually have the rectifier located on the starboard side of the powerhead close to the carburetor area.

The rectifier appears to be a round object approximately one inch (1") in diameter and also about one inch (1") high. The base of it is sort of triangular in appearance and is attached to the engine with two (2) screws/bolts..... usually one screw/bolt is larger than the other. The rectifier, depending on which one your engine uses, will have either:

One Red wire, one Yellow wire, and one Yellow/Gray wire, or One Red wire, and two Yellow wires.

Note that either of the above rectifiers could have a fourth wire which would be Yellow/Blue
********************
(Small Rectifier Test)
(J. Reeves)

Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.

Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.
 

rob 135

Petty Officer 2nd Class
Joined
Aug 8, 2013
Messages
167
Re: Cracked stator

Thank you . I did run it a few times before I replaced rectifier . I read one of your older post . Thanks for great info . I'm gonna use your timing procedure so I don't melt pistons again
 
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